Root canal pre-treatment and adhesive system affect bond strength durability of fiber posts ex vivo.

OBJECTIVES: To investigate the effect of different pre-treatments on the long-term bond strength of fiberglass posts luted either with dual-curing self-etch adhesives and core build-up composites or with a self-adhesive resin (SAR) cement. MATERIALS AND METHODS: In total, 180 human root-filled teeth received post-space preparations and three different dentin pre-treatments (PTs): PT1, ethanol (99%); PT2, ethanol-tertiary-butanol-water-solution (AH Plus Cleaner, Dentsply Sirona; York, USA); and PT3, distilled water (control). Five luting systems were used: FU, Futurabond U (Voco; Cuxhaven, Germany); CL, Clearfil DC Bond (Kuraray Noritake; Okayama, Japan); GR, Gradia Core SE Bond (GC Europe NV; Leuven, Belgium); LU, LuxaBond Universal (DMG; Hamburg, Germany); and RX, RelyX Unicem 2 (3M; Minnesota, USA). Roots were cut into six slices (1 mm thick). From each root canal region, three slices were submitted to immediate and three to post-storage push-out testing. The latter were subjected to thermocycling (5-55°C, 6.000 cycles) and stored for six months in saline solution (0.9%, 37°C). Data were analysed using repeated measures ANOVA and chi-square tests (MV±SD). RESULTS: Bond strength was significantly affected by material (p<0.0005), pre-treatment (p=0.016), and storage (p<0.0005; repeated-measures ANOVA). LU (18.8±8.1MPa) revealed significantly higher bond strength than RX (16.08±6.4MPa), GR (15.1±4.6MPa), CL (13.95±5.2MPa), and FU (13.7±6.3MPa). PT1 (16.5±6.9MPa) revealed significantly higher bond strength than PT3 (14.5±5.7MPa). CONCLUSIONS: A universal adhesive in self-etch mode combined with a core build-up material revealed higher bond strength than a SAR cement, both interacted positively with Ethanol pre-treatment. CLINICAL RELEVANCE STATEMENT: Ethanol (99%) rinsing can be recommended as part of post and core pre-treatment for the investigated luting systems.

Hard X-ray phase-contrast-enhanced micro-CT for quantifying interfaces within brittle dense root-filling-restored human teeth.

Bonding of resin composite fillings, for example following root-canal treatment, is a challenge because remaining gaps grow and lead to failure. Here, phase-contrast-enhanced micro-computed tomography (PCE-CT) is used to explore methods of non-destructive quantification of the problem, so that countermeasures can be devised. Five human central incisors with damaged crowns were root-filled followed by restoration with a dental post. Thereafter, the crowns were rebuilt with a resin composite that was bonded conventionally to the tooth with a dental adhesive system (Futurabond U). Each sample was imaged by PCE-CT in a synchrotron facility (ID19, European Synchrotron Radiation Facility) with a pixel size of 650 nm. The reconstructed datasets from each sample were segmented and analysed in a semi-automated manner using ImageJ. PCE-CT at sub-micrometre resolution provided images with an impressive increased contrast and detail when compared with laboratory micro-computed tomography. The interface between the dental adhesive and the tooth was often strongly disrupted by the presence of large debonded gaps (on average 34% ± 15% on all surfaces). The thickness of the gaps spanned 2 µm to 16 µm. There was a large variability in the distribution of gaps within the bonding area in each sample, with some regions around the canal exhibiting up to 100% discontinuity. Although only several micrometres thick, the extensive wide gaps may serve as gateways to biofilm leakage, leading to failure of the restorations. They can also act as stress-raising `cracks' that are likely to expand over time in response to cyclic mechanical loading as a consequence of mastication. The observations here show how PCE-CT can be used as a non-destructive quantitative tool for understanding and improving the performance of clinically used bonded dental restorations.

Ceramic laminate veneers: effect of preparation design and ceramic thickness on fracture resistance and marginal quality in vitro.

OBJECTIVES: The aim of the present study was to investigate the influence of five different preparation designs and two different ceramic thicknesses on margin quality and fracture resistance of ceramic laminate veneers after thermomechanical loading in vitro. MATERIALS AND METHODS: Eighty human central incisors were randomly assigned to 10 groups (n = 8) with five different preparation designs: non-prep (NP), minimally invasive (MI) = exclusively enamel-bonded, semi-invasive (SI) = 50% bonded in dentin, invasive (I) = 100% in dentin, and semi-invasive with two additional class III composite resin restorations (SI-C). IPS InLine veneers were fabricated in two thicknesses (L1 = 0.2-0.5 mm; L2 = 0.5-1.2 mm). After adhesive luting (OptiBond FL, Variolink Veneer) with light curing and polishing, specimens were stored in distilled water at 37 °C for 21 days, then thermocycled (2000 cycles between + 5 and + 55 °C), and finally mechanically loaded at the incisal edge at an angle of 45° for 2,000,000 cycles at 50 N und further 1,000,000 cycles at 100 N. Impressions were taken initially, after thermocycling, and after every 250,000 mechanical cycles in order to evaluate cracks and margin quality under a SEM. The veneers were evaluated in a light microscope (× 20) for cracks, chippings, partial, and catastrophic fractures. RESULTS: Margin quality after three million cycles revealed medians for continuous margin of 82-95% without significant differences among groups, neither at the ceramic/composite (p = 0.943) nor at the tooth/composite interface (p = 0.571). Visual inspection of veneers exhibited 22 cracks, 11 chippings, 4 partial and 4 catastrophic fractures in 38 of 80 veneers. The statistical ranking regarding fracture risk (p ≤ 0.05) was: IL1 = SIL1 = MIL1 = IL2 = CL1 = CL2, MIL2 = NPL1 = NPL2 = SIL2, IL2 = CL1 = CL2 = MIL2 = NPL1 = NPL2 = SIL2. CONCLUSIONS: Even after three million cycles with up to 100 N, all groups showed high survival rates. However, the fracture risk increases with thin veneers and preparations with medium to high dentin portions when compared to thicker veneers with preparations in enamel or partially in dentin (p ≤ 0.05). Preexisting resin composite restorations did not show any significant influence on margin quality and facture risk (p > 0.05). CLINICAL RELEVANCE: Ceramic laminate veneers are extremely durable with thin veneers and substantial enamel loss being main risk factors for fracture.

Fracture Resistance and Cusp Deflection of Lined or Non-lined Composite and Glass Hybrid Restorations Over Residual Demineralized Dentin.

PURPOSE: To assess the fracture resistance (FR) and cusp deflection (CD) of lined or non-lined composite (CO) and glass hybrid (GH) restorations over residual demineralized dentin. MATERIALS AND METHODS: In 48 extracted human premolars, artificial residual demineralized dentin was induced on pulpo-axial walls of standardized cavities. Various restorations were placed over this demineralized dentin: an experimental GH, a composite restoration (OptiBond FL+Tetric EvoCeram) without lining, or composite restorations with non-setting (Hypocal) or setting (Dycal) calcium hydroxide lining. After thermomechanical cycling, groups (n = 12) were compared regarding their CD and FR. RESULTS: CD did not differ significantly between groups. FR was significantly lower in teeth restored with GH (median: 238 N; 25th/75th percentiles: 191/287 N) than in those restored with lined or non-lined composites (median range: 517-569 N; p < 0.05/Mann-Whitney), which did not differ significantly from each other (p > 0.05). CONCLUSION: Within the conditions of this in vitro study, CH lining of pulpo-axial walls had only limited impact on CD and FR. GH showed the lowest FR and might not be optimal for restoring deep or extended cavitated lesions.

Are self-adhesive resin cements suitable as core build-up materials? Analyses of maximum load capability, margin integrity, and physical properties.

OBJECTIVES: The aim of the present study was to test a self-adhesive resin cement used as core build-up material in comparison to two commercially available core build-up materials. MATERIALS AND METHODS: Forty human anterior teeth were endodontically treated and fiber post insertion (RelyX Fiber posts) and core build-ups were performed using two core build-up materials applied with an etch-and-rinse adhesive approach (Luxacore Dual-LC and Clearfil Core-CC) and an experimental self-adhesive resin cement (SAR) in two application modes (SAR Handmix and SAR Automix). Samples were subjected to thermo-mechanical loading. Margin integrity was determined using scanning electron microscopy (SEM), and maximum load capability (Fmax) was evaluated. Physical properties of the tested materials were also examined. RESULTS: Fmax was significantly affected by the core build-up material (p < 0.0005; one-way ANOVA). CC [481 (158) N] revealed significantly higher Fmax compared to LC [226 (80) N], SAR Hand [205 (115), and SAR Automix [197 (134) N] (p < 0.05; Tukey-B). The percentage of margin quality "continuous margin" in enamel after thermo-mechanical loading (TML) differed significantly among groups (p < 0.0005; Kruskal-Wallis); CC demonstrated a significantly higher percentage of margin quality "continuous margin" compared to the other groups. Physical properties were significantly affected by the different core materials (p < 0.0005; ANOVA); CC and LC demonstrated significantly higher flexural strength compared to both SAR groups as well as significantly higher water sorption of both SAR groups compared to CC and LC. CONCLUSION: Within the limitations of the present in vitro study, we conclude that the investigated experimental self-adhesive resin cement is not suitable as a core build-up material due to the lower maximum load capability, low margin quality, and the data of the mechanical properties. CLINICAL RELEVANCE: The investigated experimental self-adhesive resin cement cannot be recommended as a core build-up material.

Resin-based pit-and-fissure sealants: microleakage reduction and infiltration enhancement using a bonding agent.

PURPOSE: To evaluate the marginal microleakage and the infiltration ability of pit-and-fissure sealants by applying the conventional sealing technique in comparison to using an additional bonding agent. MATERIALS AND METHODS: Extracted non-carious permanent molars (n = 60) were first stored in sterile saline solution and then assigned to one of two groups: group C (control) was sealed (Helioseal F) by using the conventional technique, while in group BA (bonding agent), a bonding agent (OptiBond FL) was additionally applied prior to sealing. The teeth were thermocycled (1000 cycles, 5°C to 55°C, dwell time 30 s), then varnished and immersed in 5% methylene blue solution for 24 h. After embedding and sectioning each tooth into 6-12 slices, the presence of microleakage, unfilled areas, and air bubbles trapped in the sealant were assessed with a stereomicroscope. RESULTS: A higher proportion of microleakage was found under sealants applied without the additional use of the bonding agent. A statistically significant difference in microleakage was noted between the groups (p = 0.045). Regarding the presence of unfilled areas, a statistically significant difference between the groups was observed (p < 0.001), especially since no unfilled areas were found at all in the samples of the group using the bonding agent. Regarding the amount of air bubbles trapped in the sealant, no statistically significant difference was observed between the two groups (p = 0.829). CONCLUSION: Under these in vitro conditions, sealant procedures using an additional bonding agent applied beforehand significantly improved fissure infiltration and microleakage prevention significantly.

Do chlorhexidine and ethanol improve bond strength and durability of adhesion of fiber posts inside the root canal?

OBJECTIVES: The aim was to investigate the effects of chlorhexidine and ethanol pretreatment of the root canal on push-out bond strengths and durability of adhesion of fiber posts luted with two different adhesive strategies. MATERIALS AND METHODS: One hundred twenty human anterior teeth were endodontically treated. After post space preparation, the root canals were irrigated using 1 % sodium hypochlorite (NaOCl) applied with passive ultrasonic irrigation followed by distilled water (control). In pretreatment (PT) group, chlorhexidine (CHX) root canals were irrigated using 2 % chlorhexidine; and in the PT group, 99 % ethanol was used prior application of the luting agent. Two different post-and-luting systems with an etch-and-rinse (CX) adhesive approach (n = 60) and a self-adhesive resin cement (RX; n = 60) were inserted into the root canals. Bond strengths were evaluated initially and after thermocycling and storage for 6 months using push-out tests. RESULTS: Bond strength was significantly affected by the adhesive strategy (p < 0.0005), the pretreatment (p < 0.0005) and the location inside the root canal (p < 0.0005; repeated measurement ANOVA). Ethanol significantly increased bond strengths irrespective of the luting agent used compared to the control and CHX group (p < 0.05; Tukey's B). CONCLUSION: Ethanol significantly increased bond strength of the CX and the RX system inside the root canal and could be recommended as a final rinse for luting fiber posts using an ethanol-based etch-and-rinse adhesive system or self-adhesive resin cement. CLINICAL RELEVANCE: PT of the root canal using ethanol seems to facilitate adhesive luting of fiber posts with the tested adhesive system and luting cements.

Various irrigation protocols for final rinse to improve bond strengths of fiber posts inside the root canal.

Irrigation after post space preparation and its effects on the bond strength of different adhesive strategies are still an issue of interest. The aim of the present study was to investigate the effects of various irrigation protocols (IPs) on the push-out bond strengths of fiber posts. One-hundred and fifty extracted human anterior teeth were divided into three groups (n = 50 each) and endodontically treated. The post space was irrigated before post placement using the following five IPs in each group: IP1 (control): 5 ml of distilled water; IP2: 5.25% sodium hypochlorite (NaOCl) applied with passive ultrasonic irrigation (PUI); IP3: 1% NaOCl applied with PUI; IP4: 18% ethylenediaminetetracetic acid (EDTA) followed by 5.25% NaOCl; and IP5: 2% chlorhexidine (CHX). Fiber posts placement in each group was performed using three different adhesive strategies. A self-etch adhesive system revealed higher bond strength (16.2 ± 6.9 MPa) compared with an etch-and-rinse adhesive (8.5 ± 4.2 MPa) and a self-adhesive resin cement (9.2 ± 4.7 MPa). The use of 18% EDTA/5.25% NaOCl increased the bond strength of the self-adhesive resin cement. Conversely, this IP decreased the bond strength for the etch-and-rinse adhesive system, whilst 1% NaOCl enhanced the bond strength for the same system. Consequently, each adhesive strategy may need to be adapted to a specific IP.

Enamel margin integrity of Class I one-bottle all-in-one adhesives-based restorations.

PURPOSE: To evaluate marginal adaptation of Class I restorations in enamel using contemporary one-bottle all-in-one adhesives, stressed by thermocycling (TC) and mechanical loading (ML). MATERIALS AND METHODS: Ninety-six extracted human molars were prepared (standard Class I cavities: 3 mm deep, 6 mm wide mesio-distally, and 4 mm wide bucco-lingually). Twelve adhesive systems were used: OptiBond FL (OPT), Clearfil SE Bond (CSE) and Adper Prompt L-Pop (PLP) as controls, compared with nine one-bottle all-in-one adhesives - AdheSe One (AHO), Adper Easy Bond (EB), Bond Force (BF), G-Bond (GB), iBond Self Etch (IB), One Coat 7.0 (OC), OptiBond All-in-one (OPA), Clearfil Tri-S-Bond (TSB), Xeno V (XV). All teeth were restored using Filtek Z250 placed in three (one horizontal, two oblique) increments. Enamel margins were evaluated following 21 days of water storage, after thermocycling (2000 cycles: 5°C to 55°C), and after mechanical loading (150,000 cycles, 50 N). After each step, replicas were produced and quantitative SEM margin analysis was performed (200X) using defined criteria. RESULTS: The median values of % "continuous margin" following TC and ML, respectively, were: OPT(98.6/96.2), CSE(95.4/90.9), BF(81.7/68.1), GB(81.1/65.0), OPA(83.0/68.1), OC(64.1/41.3), TSB(59.3/42.2), EB(57.1/42.6), IB(38.4/27.6), PLP(36.6/21.5), XV(45.0/30.0), AHO(17.7/5.4). Statistical evaluation (Kruskal-Wallis test with Bonferroni adjustment, p < 0.05) revealed the following ranking for ML: OPT=CSE>BF=OPA=GB>OC=EB=TSB=XV =IB=PLP>AHO. CONCLUSION: All one-bottle all-in-one adhesives exhibited statistically significant lower marginal qualities in enamel compared to the etch-and-rinse system OPF and the two-step self-etching system CSE. The results obtained for GB, OPA and BF, however, were better than for the other all-in-one adhesives.

Secondary Caries Adjacent to Bulk or Incrementally Filled Composites Placed after Selective Excavation In Vitro.

OBJECTIVES: selective caries excavation (SE) is recommended for deep carious lesions. Bulk fill composites (BF) may be considered to restore SE-cavities. We compared the susceptibility for secondary caries adjacent to BF versus incrementally filled composites (IF) in SE and non-selectively excavated teeth (NS) in vitro. METHODS: in 72 extracted human premolars, artificial caries lesions were induced on pulpo-axial walls of standardized cavities. The lesions were left (SE) or removed (NS), and teeth were restored using two BF, GrandioSO x-tra/Voco (BF-Gra) and SDR/Dentsply (BF-SDR), and an IF, GrandioSO/Voco (IF-Gra) (n = 12/group for SE and NS). After thermo-mechanical cycling (5-55 °C, 8 days), teeth were submitted to a continuous-culture Lactobacillus rhamnosus biofilm model with cyclic loading for 10 days. Mineral loss (ΔZ) of enamel surface lesions (ESL), dentin surface lesions (DSL), and dentin wall lesions (DWL) was analyzed using transversal microradiography. RESULTS: ΔZ was the highest in DSL, followed by ESL, and it was significantly lower in DWL. There were no significant differences in ΔZ between groups in DSL, ESL, and DWL (p > 0.05). Regardless of lesion location, ΔZ did not differ between SE and NS (p > 0.05). CONCLUSIONS: BF and IF both showed low risks for DWL (i.e., true secondary caries) after SE in vitro, and surface lesion risk was also not significantly different between materials. SE did not increase secondary caries risk as compared with NS. CLINICAL SIGNIFICANCE: the risk of secondary caries was low after selective excavation in this study, regardless of whether bulk or incrementally filled composites were used.

OCT evaluation of the internal adaptation of ceramic veneers depending on preparation design and ceramic thickness.

OBJECTIVES: In-vitro evaluation of the influence of preparation design and thickness of ceramic veneers on the interfacial bond using optical coherence tomography (OCT). METHODS: Sixty-four central incisors were randomly assigned to four preparation designs differing from no to complete dentine exposure (n = 16 each): non-prep (NP), minimal-invasive (MI, no dentine exposure), semi-invasive (SI, 50% dentine) and invasive (I, 100% dentine). Ceramic veneers (IPS InLine Veneer) of two thicknesses (0.2-0.5 mm (T1) and > 0.5-1.2 mm (T2)) were etched, silanized, and adhesively luted (Optibond FL, Variolink Veneer). After water storage (37 °C, 21d), thermocycling (2000 cycles, 5°-55 °C), and mechanical loading (2 + 1 million cycles, 50 + 100 N) specimens were imaged by spectral-domain OCT (Telesto II, Thorlabs). Adhesive defects at the ceramic-composite and tooth-composite interfaces were quantified on 35 equidistantly distributed OCT B-scans (length, %). Statistical differences were verified with Wilcoxon-/Mann-Whitney-U-test (α = 0.05). RESULTS: Adhesive defects appeared in all groups at both interfaces, albeit to differing extents (0.1 - 31.7%). NP and MI veneers showed no significant differences at the interfaces (pi > 0.05). In groups, SI and I, significantly more adhesive defects appeared at the tooth-composite compared to the veneer-composite interface (pi ≤ 0.039). The following preparation designs and veneer thicknesses showed differences (pi ≤ 0.021): Veneer-composite: NP-T1 < I-T1, MI-T1 < I-T1, I-T1 > I-T2; Tooth-composite: NP-T1 < SI-T1, NP-T1 < I-T1, NP-T2 > MI-T2, MI-T1 < SI-T1, MI-T1 < I-T1, SI-T1 < I-T1, MI-T2 < SI-T2, MI-T2 < I-T2. SIGNIFICANCE: The interface adhesion of ceramic veneers was influenced by the preparation design and the veneer thickness. A ceramic thickness of at least 0.5 mm and a preparation without exposing dentine is advantageous for the interfacial bond.

Restoring strength of incisors with veneers and full ceramic crowns.

PURPOSE: The aim was to determine the in vitro fracture resistance of incisors restored with veneers and full ceramic crowns compared to unrestored teeth. MATERIALS AND METHODS: Seventy intact, extracted human maxillary central incisors were randomized and assigned to 7 groups (n = 10). The teeth in group 1 remained intact (control). The teeth in groups 2 to 6 were prepared and IPS Empress restorations were conditioned and bonded using an adhesive luting cement, Variolink II/Syntac (group 2: labial veneer with incisal overlap, group 3: 3/4 veneer with margin in enamel, group 4: 3/4 veneer with margin in dentin, group 5: crown with margin in enamel, group 6: crown with margin in dentin group 7: veneer on worn tooth. After finishing and polishing, specimens were stored in water and thermocycled for 2000 cycles between 5 degrees C and 55 degrees C. The maximal fracture load of the specimens (40-degree inclination) was determined using the universal testing machine (Zwick) at a constant crosshead speed (0.5 mm/min). The statistical analysis was performed using the Kruskal-Wallis test with Bonferroni correction (p < 0.05). Fracture surfaces were qualitatively analyzed by SEM. RESULTS: All restored teeth with cervical preparation margins in enamel showed a fracture load not significantly different from the intact teeth (control). Restored teeth with cervical preparation margins in dentin showed a significantly lower fracture load. All restorations showed a fracture load far above 400 N, serving as functional reference for anterior teeth. The failures were predominantly cohesive. CONCLUSION: For the restoration of tooth strength, defining the finishing lines of veneers and crowns in enamel is recommended. Restorations with finishing lines in dentin resulted in significant loss of strength. Three-quarter veneers with finishing lines in enamel are functionally equal to crowns with the advantage of conserving tooth structure.

Effect of pre-heated composites and flowable liners on Class II gingival margin gap formation.

PURPOSE: To evaluate the effect of preheated composites (PHC) and flowable liners (FL) on the gingival margin gap formation of Class II composite restorations compared to the placement of room temperature composites (RTC). MATERIALS AND METHODS: Class II composite restorations were prepared on 40 extracted mandibular third molars, with the gingival margin located 1 mm below the CEJ in dentin. Optibond FL (Kerr), microhybrid Filtek Z-250 (3M ESPE) and Flow-It (Jeneric Pentron) were used to evaluate five study groups: 1) PHC, 130 degrees F/54.4 degrees C; 2) PHC, 155 degrees F/68.3 degrees C; 3) FL cured prior to the first increment composite; 4) FL cured simultaneously with the first increment composite and 5) RTC (Control). Impressions were taken with quick set polyvinyl siloxane impression material, and epoxy resin replicas were evaluated under SEM (200x). Gingival margin adaptation was quantitatively evaluated in terms of percentage of gap formation according to a modified ordinal scoring criteria. All margins were evaluated twice for reliability assessment. A non-parametric Kruskal-Wallis test was used to determine whether significant differences in gap formation existed among the study groups. RESULTS: A high level of agreement was observed between duplicate measurements of the percentage of gap formation (intra-class correlation = 0.956, p < 0.0001). There was no evidence of a difference among groups defined by placement technique (p = 0.82). Overall, the mean gap-percentage for the 40 margins evaluated was 6.3 (Median = 1.1; SD = 14.8). CONCLUSIONS: Gingival margin adaptation was not improved relative to the control by any of the placement techniques tested. No significant differences in gap formation were found among the study groups. A high degree of intra-examiner reliability was confirmed.

Improving the Bond Strength of Radiographically Tagged Caries Lesions In Vitro.

After selective carious tissue removal, residual carious lesions remain radiographically detectable. Radiopaque tagging resolves the resulting diagnostic uncertainty but impedes bond strengths of adhesives to tagged dentin. We developed a protocol mitigating these detrimental effects. A 30%/50%/70% SnCl2 solution was dissolved in distilled water or a 30%/50%/90% ethanol solution (E30/60/90) and applied to artificially induced dentin lesions. Tagging effects were radiographically evaluated using transversal wavelength-independent microradiography (n = 6/group). Groups with sufficient tagging effects at the lowest SnCl2 concentrations were used to evaluate how tagging affected the microtensile bond strength of a universal adhesive (Scotchbond Universal) to sound and carious dentin (n = 10/group). Two different protocols for removing tagging material were tested: 15 s phosphoric acid etching and 5 s rotating brush application. Scanning/backscattered electron microscopy (SEM/BSE) and energy-dispersive X-ray spectroscopy (EDS) were used to assess surfaces after tagging and removal. The most promising removal protocol was revalidated microradiographically. Tagging significantly increased the radiopacity, with consistent effects for 30% SnCl2 dissolved in water or E30. Microscopically, tagged surfaces showed a thick carpet of SnCl2, and tagging reduced bond strengths significantly on carious dentin but not on sound dentin (p < 0.01). On carious dentin, removal of tagging material using acid etching and rotating brush was microscopically confirmed. Acid etching also mitigated any bond strength reduction (median: 21.3 MPa; interquartile range: 10.8 MPa) compared with nontagged dentin (median: 17.4 MPa; interquartile range: 20.6 MPa). This was not the case for brushing (median: 13.2 MPa; interquartile range: 13.9 MPa). Acid etching minimally reduced the radiographic tagging effect (p = 0.055). Phosphoric acid etching reduces the detrimental bond-strength effects of tagging without significantly decreasing radiographic tagging effects when using a universal adhesive.

Interface homogeneity of adhesively luted glass fiber posts.

OBJECTIVE: The aim of this study was to light microscopically evaluate the homogeneity of the cement interface of an adhesively luted glass fiber post (GFP) by using a new cement application aid compared to a conventional post cementation method. METHODS: Twenty artificial root canals (n = 5) received GFP under the following experimental conditions: I = RelyX Unicem applied with a new application aid, II = RelyX Unicem, III = Panavia F 2.0 and IV = Variolink II (groups II-IV with conventional post cementation). From all specimens standardized photographs were taken perpendicularly to the post surface under a light-optical microscope from two opposite sides. The depicted cement interfaces were analysed using surface-analyzing software and related to the complete three-dimensional surface of the cement interface. Non-parametric tests were used to compare median values of the observed inhomogeneities (alpha = 5%). RESULTS: The median values (%) of inhomogeneities within the cement interface for the cervical, middle, and apical level of analysis were: I = 2, 2, 7; II = 15, 19, 24; III = 8, 16, 39; IV = 11, 16, 29. For the complete post length, median values (%) of inhomogeneities were: I = 4; II = 19; III = 20; IV = 18. SIGNIFICANCE: The conventional application technique for luting endodontic post results in a large number of voids and bubbles. The combination of a flexible root-canal-shaped application aid achieves a more homogenous cement interface for the self-adhesive luting material tested.

Restoring the Carious Lesion.

Restoring carious lesions can be challenging, especially for deep lesions in proximity to the pulp. A number of factors can influence restoration longevity. This chapter will discuss aspects that should be considered when restoring carious lesions. In the first part, factors that might have an effect on the pulp such as preparation trauma, tooth hypersensitivity, and the use of liners will be described. In the second part, the challenges and limitations of adhesive bonding to (sound and carious) dentine will be discussed. Lastly, recommendations on the suitability of different bonding techniques and restorative materials in different situations will be given.

Restoration integrity, but not material or cementation strategy determined secondary caries lesions next to indirect restorations in vitro.

OBJECTIVE: Secondary caries lesions next to direct restorations are associated with the restoration material and the integrity of the tooth-restoration-interface (presence of interfacial gaps) as well as the application of masticatory forces. It remains unclear if this is true for indirect restorations. We aimed to evaluate secondary lesions next to conventionally-cemented partial gold (PG) and adhesively-cemented partial ceramic (PC) restorations, placed with or without interfacial gaps. METHODS: In human molars, standardized two-surfaced cavities were prepared. Four groups (restoration material+cementation strategy) were compared: (1) gold+glass ionomer cement (Degudent/Ketac Cem), (2) lithium disilicate ceramic+self-adhesive resin cement (IPS e.max Press/RelyX Unicem 2), (3) lithium disilicate ceramic+self-etch adhesive+resin cement (IPS e.max Press/Adhese Universal/Variolink Esthetic DC), (4) lithium disilicate ceramic+etch-and-rinse adhesive+resin cement (IPS e.max Press/Syntac/Variolink Esthetic DC). Half of the restorations received a simulated interfacial gap (mean gap height was 237µm), while the other half did not (n=12/group). Specimens were submitted to a Lactobacillus rhamnosus-monospecies-biofilm-model with concomitant cyclic loading for 10 days. Mineral loss (ΔZ) of enamel-surface-lesions (ESL) and dentin-wall-lesions (DWL) was analyzed using transversal microradiography. RESULTS: For ESL, neither the presence of an interfacial gap nor the restoration material nor the cementation strategy had a significant influence on ΔZ (p>0.05/Generalized Linear Modelling). For DWL, ΔZ was significantly higher beneath restorations with interfacial gaps (p=0.003/GLM); the restoration material and cementation strategy did not have a significant influence (p>0.05). SIGNIFICANCE: The presence of interfacial gaps, but not the restoration material or cementation strategy determined secondary caries lesions next to indirect restorations in vitro.

Effectiveness of all-in-one adhesive systems tested by thermocycling following short and long-term water storage.

PURPOSE: To evaluate and compare the marginal integrity of in vitro Class V restorations made with all-in-one adhesive systems by thermocycling after different periods of water storage, to provide an analysis of static and quasi-dynamic deterioration in water. MATERIALS AND METHODS: Standardized Class V cavities (17 groups, 8 specimens each) were prepared in extracted human caries-free anterior teeth. The cavities were filled using 14 all-in-one adhesive systems/composite resin combinations in addition to the multi-bottle adhesive systems Syntac and OptiBond FL (etch-and-rinse technique) and Clearfil SE Bond (self-etching) as controls. The samples were thermocycled after water storage for 21 days, after 1 year and again after 3 years (2000 cycles between 5 and 55 degrees C) and replicas were made before and after each thermocycling treatment (TC) for quantitative marginal analysis in the SEM. RESULTS: In dentin, marginal adaptation showed no significant differences between all groups after the first TC. After one year of water storage and a second TC, the results for Prompt L-Pop (1999), Adper Prompt L-Pop/Tetric Ceram, and One-up Bond F Plus showed a statistically significant decrease of margin quality 1 (MQ1) score compared to the reference groups. When the all-in-one adhesives G-Bond, AQ-Bond, Hybrid Bond, and One-up Bond F Plus were used, the enamel margins of restorations showed lower percentages of "continuous margins" (p < 0.05) after 1 year of water storage and TC. Of the materials tested after 3 years of water storage and TC, only AQ Bond had a significantly lower MQ1 score. CONCLUSION: While all materials exhibited deterioration in the MQ1 quality score, the rate of deterioration varied, and the results show that different materials have different deterioration rates after initial vs long-term water storage. The deterioration along margins in dentin was not as extensive as predicted from other studies; however, the results from the enamel margins show that one-bottle all-in-one adhesives seem to be significantly affected by water storage. The results of this study suggest that the all-in-one adhesive group members perform very differently from each other: thus, data need to be explored further at the level of each different adhesive product.

Six-month clinical evaluation of XP BOND in noncarious cervical lesions.

PURPOSE: To evaluate the 6-month clinical performance of the etch-and-rinse one-bottle adhesive system XP BOND, used in combination with the composite resin Ceram X duo for the restoration of Class V noncarious cervical lesions (NCCL). MATERIALS AND METHODS: XP BOND was tested in a total of 40 patients who received two Class V Ceram X duo restorations, Adper Scotchbond 1 XT was used as a control. After cleaning the teeth, the surface of the NCCL was treated using a carbide bur in dentin and a 40-microm diamond bur in enamel with no retentive preparations. The lesions were filled with two increments of Ceram X duo after the application of the respective adhesive by a single operator according to manufacturer's instructions. After 6 months, the retention and the marginal integrity were evaluated. RESULTS: Thirty-eight of 40 patients were evaluated after 6 months by two clinicians according to modified USPHS criteria, and all restorations using XP BOND were still in place. In the control group (using Adper Scotchbond 1XT), one restoration was lost. The statistical evaluation (chi2 test) showed no significant differences in any of the criteria. No difference of marginal integrity was found between the two adhesive systems. CONCLUSION: XP BOND meets the ADA success criteria after 6 months.