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The retrospective survival study (1995-2004) by Balkenhol et al. [1]. led to changes in the decision-making process for treatment with post and cores (special focus on the covering prosthetic restoration while deciding for treatment with post and cores, high primary friction at the try-in stage for conventional cementation, only indirect fabrication technique, no semi-precious alloy) in our clinic. The aim of this study was to examine the influence of these changes on the survival probability.In the observation period (2004-2020) 653 patients received in total 953 post and cores. The patient files were analysed due to the parameters: Type of covering prosthetic restoration, location, type of tooth, luting material, post and core material, bone attachment, therapist and cause of failure. According to the previous study the survival probability was assessed using Kaplan-Meyer analysis. Cox regression was used to assess the risk of failure and identify possible covariates.The average survival time of the post and cores was 10.9 years. The cumulative failure rate was 28.2%. A significant influence on the survival time (Kaplan-Meyer analysis) could be found for the parameters: Type of covering prosthetic restoration, location, type of tooth, post and core material and bone attachment. The multifactorial survival analysis (Cox regression) showed a significant influence of the age of the patient at the time of fitting the post, the type of covering prosthetic restoration and the bone attachment.The changes in the decision-making process did not lead to a better survival probability.The conclusions stated in the previous study were not strict enough. Treatments with post and cores should be critically scrutinized on the basis of covering prosthetic restoration and bone attachment. Post and cores under primary crown retained RPDs should be avoided because of the bad survival probability.

Objectives: To explore fatigue limits of ceramic endocrowns for premolars. Methods: Forty-eight devitalized premolars were cut at the CEJ. They were restored with standardized CAD–CAM lithium disilicate reinforced ceramic restorations (IPS e.max CAD, Ivoclar-Vivadent) and divided into four Groups (n = 12): overlays (Group A, no endo-core, negative control), endocrowns with an endo-core of 2 mm (Group B), 4 mm (Group C) and crowns with post and core (Group D, positive control). All specimens were first submitted to thermo-mechanical cyclic loading (TCML)(1.7 Hz, 49 N, 600000 cycles, 1500 thermo-cycles). Margins were analysed before and after the loading. Survived specimens were then submitted to cyclic isometric stepwise loading (5 Hz, 200N to 1200N) until completion of 105000 cycles or failure. In case of fracture, fragments were analysed using SEM and failure mode was determined. Results of stepwise loading were statistically analysed by Kaplan–Meier life survival analysis and log rank test (p = 0.05). Results: All the specimens survived the TCML test except four specimens of Group A (early restorations’ debonding). No difference in percentages of closed margins was found between endocrowns (Groups B, C) and crowns (Group D). After the stepwise test, differences in survival within the groups were not statistically significant. Most of restorations experienced non-reparable fracture. Conclusions: Endocrowns with both 2-mm and 4-mm long endo-cores displayed outcomes after fatigue equivalent to classical crowns. Results of this study discourage the use of flat overlays with only adhesive retention. Clinical significance: When restoring extremely destroyed devitalized premolars, adhesive strategies should be coupled to a macro-mechanical retention in the root.

Objectives To investigate debonding and stability of CAD/CAM composite crowns as a function of (a) preparation design, (b) fitting parameters of the milling process, and (c) type of cementation. Methods Extracted human molars were prepared providing either retentive design (R) or no retention (NR). After digitalization, full-contour crowns were milled using either optimal (OF) or reduced (RF) fitting parameters. A total of 112 crowns were milled from the composite materials Lava Ultimate (L) and Grandio Blocs (G) and a ceramic reference. The crowns were either cemented with self-adhesive cement (SE) or were adhesively bonded (A). After water storage, thermal cycling and mechanical loading was performed. Restorations which failed during storage or TCML were analyzed using scanning electron microscopy and surviving restorations were loaded to fracture. Results L crowns survived only with R/OF/A conditions. No debondings were observed for G crowns with OF/A conditions as well as R/OF/SE conditions. Surviving L crowns showed mean fracture values of 1227 N (NR/RF/A) and 1534 N (R/OF/A), and for surviving G crowns mean fracture values of 2021 N (R/OF), 1872 N (R/RF), 2242 N (NR/OF), and 2070 N (NR/RF) were identified. Conclusions Retentive preparation design and/or optimal fitting reduced the number of debondings. For composite restorations, adhesive cementation should be preferred. Clinical significance Preparation design, fitting parameters as well as the type of cementation impact the performance of composite crowns. Retentive preparation design and/or good fitting are mandatory to avoid debonding of composite restorations; adhesive cementation should be preferred in any case.

Objective The purpose of this study was to evaluate the 10-year clinical performance of zirconia-based inlay-retained fixed dental prostheses (IRFDP). Methods For replacement of a molar in 27 patients, 30 IRFDP were luted by use of different cements, Panavia F (Kuraray Europe GmbH) or Multilink Automix (Ivoclar Vivadent GmbH), with use of inlay/inlay, inlay/full-crown, or inlay/partial-crown retainers for anchorage. Frameworks were milled from yttria-stabilized zirconia (IPS e.maxZirCAD; Ivoclar Vivadent GmbH) and fully veneered with pressable ceramic (IPS e.max ZirPress; Ivoclar Vivadent GmbH). Before luting, the IRFDP were silica-coated (Rocatec; 3 M Espe) and silanized (Monobond S; Ivoclar Vivadent GmbH). Complications (for example, chipping or delamination of the veneering ceramic, debonding, secondary caries, endodontic treatment, and abutment tooth fracture) and failure were reported, by use of standardized report forms, 2 weeks, 6 months, and 1, 2, and 10 years after cementation. Statistical analysis included Kaplan–Meier survival and success (complication-free survival) and Cox regression analysis (α = 0.05 for all). Results During the 10-year observation period, the complications most often observed were chipping of the veneer and debonding. Twenty-five restorations failed and one participant dropped out. Cumulative 10-year survival and success were 12.1% and 0%, respectively. The design of the retainer, use of a dental dam, choice of cement, and location in the dental arch had no statistically significant effect on the occurrence of complications. Conclusions Use of fully veneered zirconia-based IRFDP with this technique cannot be recommended. Clinical significance A large incidence of complications and poor survival were observed for fully veneered zirconia-based IRFDP, revealing an urgent need for further design improvements for this type of restoration. This, again, emphasizes the need for testing of new restoration designs in clinical trials before implementation in general dental practice.

Objectives To test the hypothesis that there is no difference in the in vivo maximum wear of enamel opposing monolithic zirconia crowns, enamel opposing porcelain fused to metal crowns and enamel opposing enamel. Methods Thirty patients needing single crowns were randomized to receive either a monolithic zirconia or metal-ceramic crown. Two non-restored opposing teeth in the same quadrants were identified to serve as enamel controls. After cementation, quadrants were scanned for baseline data. Polyvinylsiloxane impressions were obtained and poured in white stone. Patients were recalled at six-months and one-year for re-impression. Stone models were scanned using a tabletop laserscanner to determine maximum wear. Statistical analysis was performed using Mann-Whitney U to determine any significant differences between the wear of enamel against zirconia and metal-ceramic crowns. Results Sixteen zirconia and 14 metal-ceramic crowns were delivered. There were no statistical differences in mean wear of crown types (p = 0.165); enamel antagonists (p = 0.235) and enamel controls (p = 0.843) after one year. Conclusion Monolithic zirconia exhibited comparable wear of enamel compared with metal-ceramic crowns and control enamel after one year. Significance This study is clinically significant because the use of polished monolithic zirconia demonstrated comparable wear of opposing enamel to metal-ceramic and enamel antagonists.

Objectives This study evaluated the clinical outcome of all-ceramic resin-bonded fixed dental prostheses (RBFDPs) with a cantilevered single-retainer design made from zirconia ceramic. Methods Forty-two anterior RBFDPs with a cantilevered single-retainer design were made from yttrium oxide-stabilized zirconium oxide ceramic. RBFDPs were inserted using Panavia 21 TC as luting agent after air-abrasion of the ceramic bonding surface. Results During a mean observation time of 61.8 months two debondings occurred. Both RBFDPs were rebonded using Panavia 21 TC and are still in function. A caries lesion was detected at one abutment tooth during recall and was treated with a composite filling. Therefore, the overall six-year failure-free rate according to Kaplan–Meier was 91.1%. If only debonding was defined as failure the survival rate increased to 95.2%. Since all RBFDPs are still in function the overall survival rate was 100% after six years. Conclusions Cantilevered zirconia ceramic RBFDPs showed promising results within the observation period. Clinical Significance Single-retainer resin-bonded fixed dental prostheses made from zirconia ceramic show very good mid-term clinical survival rates. They should therefore be considered as a viable treatment alternative for the replacement of single missing anterior teeth especially as compared to an implant therapy.

The aim of the study was to evaluate the marginal and internal fit of heat-pressed and CAD/CAM fabricated all-ceramic onlays before and after luting as well as after thermo-mechanical fatigue.Seventy-two caries-free, extracted human mandibular molars were randomly divided into three groups (n=24/group). All teeth received an onlay preparation with a mesio-occlusal-distal inlay cavity and an occlusal reduction of all cusps. Teeth were restored with heat-pressed IPS-e.max-Press* (IP, *Ivoclar-Vivadent) and Vita-PM9 (VP, Vita-Zahnfabrik) as well as CAD/CAM fabricated IPS-e.max-CAD* (IC, Cerec 3D/InLab/Sirona) all-ceramic materials. After cementation with a dual-polymerising resin cement (VariolinkII*), all restorations were subjected to mouth-motion fatigue (98 N, 1.2 million cycles; 5°C/55°C). Marginal fit discrepancies were examined on epoxy replicas before and after luting as well as after fatigue at 200× magnification. Internal fit was evaluated by multiple sectioning technique. For the statistical analysis, a linear model was fitted with accounting for repeated measurements.Adhesive cementation of onlays resulted in significantly increased marginal gap values in all groups, whereas thermo-mechanical fatigue had no effect. Marginal gap values of all test groups were equal after fatigue exposure. Internal discrepancies of CAD/CAM fabricated restorations were significantly higher than both press manufactured onlays.Mean marginal gap values of the investigated onlays before and after luting as well as after fatigue were within the clinically acceptable range. Marginal fit was not affected by the investigated heat-press versus CAD/CAM fabrication technique. Press fabrication resulted in a superior internal fit of onlays as compared to the CAD/CAM technique.Clinical requirements of 100 μm for marginal fit were fulfilled by the heat-press as well as by the CAD/CAM fabricated all-ceramic onlays. Superior internal fit was observed with the heat-press manufacturing method. The impact of present findings on the clinical long-term behaviour of differently fabricated all-ceramic onlays warrants further investigation.

To investigate if resin-cementation of a soda lime glass dental analogue could elucidate information regarding the pattern of resin-reinforcement when coated in an environment actively scavenged of moisture.192 soda lime disc-shaped specimens (alumina particle air abraded, hydrofluoric acid-etched and silane coated) were randomly assigned to eight groups (n=24 per group) prior to resin-coating at seating loads of 5 N (Groups A-D) and 30 N (Groups E-H) in an environment where moisture was actively scavenged and maintained below 15 ppm. Following one week storage the discs were tested in biaxial flexure at crosshead rates of 0.01, 0.1, 1 and 10mm/min. Analysis of group means was performed utilising a general linear model univariate analysis and post hoc all paired Tukey tests (P0.05).The general linear model univariate analysis identified the mean biaxial flexure strength (BFS) was significantly influenced by the factors resin-cementation seating load (P0.001) and crosshead speed of the applied load (P0.001) with a significant interaction (P=0.008) between both factors. The linear logarithmic regression curves fitted to the group mean BFS data plotted against the crosshead speed highlighted significant differences between the pattern of resin-strengthening for the cementation loads and testing conditions.The decrease in resin-penetration expected within the 'resin-ceramic hybrid layer' following removal of the 30 N seating load was proposed as the modifying resin-strengthening parameter. These observations are supported by the viscoelastic and creep behaviour of resins at slow testing rates which becomes the dominant or determining phenomenon.

Objectives The aim of this study was to identify the most appropriate alloy composition and melting technique by evaluating the marginal accuracy of cast metal-ceramic crowns. Methods Seventy standardised stainless-steel abutments were prepared to receive metal-ceramic crowns and were randomly divided into four alloy groups: Group 1: palladium-gold (Pd-Au), Group 2: nickel-chromium-titanium (Ni-Cr-Ti), Group 3: nickel-chromium (Ni-Cr) and Group 4: titanium (Ti). Groups 1, 2 and 3 were in turn subdivided to be melted and cast using: (a) gas oxygen torch and centrifugal casting machine (TC) or (b) induction and centrifugal casting machine (IC). Group 4 was melted and cast using electric arc and vacuum/pressure machine (EV). All of the metal-ceramic crowns were luted with glass-ionomer cement. The marginal fit was measured under an optical microscope before and after cementation using image analysis software. All data was subjected to two-way analysis of variance (ANOVA). Duncan's multiple range test was run for post - hoc comparisons. The Student's t -test was used to investigate the influence of cementation ( α = 0.05). Results Uncemented Pd-Au/TC samples achieved the best marginal adaptation, while the worst fit corresponded to the luted Ti/EV crowns. Pd-Au/TC, Ni-Cr and Ti restorations demonstrated significantly increased misfit after cementation. Conclusions The Ni-Cr-Ti alloy was the most predictable in terms of differences in misfit when either torch or induction was applied before or after cementation. Cemented titanium crowns exceeded the clinically acceptable limit of 120 μm. Clinical significance The combination of alloy composition, melting technique, casting method and luting process influences the vertical seal of cast metal-ceramic crowns. An accurate use of the gas oxygen torch may overcome the results attained with the induction system concerning the marginal adaptation of fixed dental prostheses.

To determine the resin-strengthening dependence of a soda-lime-glass analogue for dental porcelain as a function of biaxial flexure strength (BFS), test crosshead rate and cementation seating load.Disc-shaped soda-lime glass specimens were divided into twelve groups (n=24), alumina particle air abraded and hydrofluoric acid-etched. Specimens (Groups A-D) were stored in a desiccator prior to testing at crosshead rates of 0.01, 0.1, 1 and 10mm/min, respectively. The remaining specimens were silane treated, Rely-X Veneer resin-coated with a seating load of 5N (Groups E-H) and 30N (Groups I-L) prior to light irradiation at 480±20mW/cm(2), 24h dry storage and BFS testing at 0.01, 0.1, 1 and 10mm/min, respectively. A linear logarithmic regression curve was fit to the raw data to elucidate static fatigue effects of the soda-lime-glass. Analysis of group means was performed utilising a general linear model univariate analysis and post hoc all paired Tukey tests (P0.05).The linear logarithmic regression curve demonstrated the static fatigue effects of the soda-lime-glass analogue. Rely-X Veneer resin-coating (Groups E-L) resulted in significant increases in the mean BFS data for all crosshead rates examined (all P0.001). However, the pattern of rate dependence effects on resin-cementation deviated from the log relationship observed with the uncoated controls.This study further highlights that when slow crack growth is simulated during testing, valuable insights into the significant modification of a hereto well described phenomenon such as resin-strengthening mediated by the resin-ceramic hybrid layer is provided.

Objectives (1) To chemically characterise Y-TZP surface via X-ray photoelectron spectroscopy (XPS) and evaluate the surface energy levels (SE) after non-thermal plasma (NTP). (2) To test the microtensile bond strength (MTBS) of Y-TZP bonded to cured composite disks, after a combination of different surface conditioning methods. Methods Twenty-four Y-TZP discs (13.5 mm × 4 mm) were obtained from the manufacturer and composite resin (Z-100) discs with similar dimensions were prepared. All discs were polished to 600 grit and divided into 8 groups ( n = 3 disks each), four control (non-NTP treated) and four experimental (NTP treated for 10 s) groups. All groups received one of the four following treatments prior to cementation with Rely × Unicem cement: sand-blasting (SB), a Clearfil ceramic primer (MDP), sand-blasting + MDP (SBMDP), or baseline (B), no treatment. SE readings and surface roughness parameters were statistically analysed (ANOVA, Tukey's, p t -tests were used to compare groups on MTBS. Results XPS showed increase in O and decrease in C elements after NTP. The polar component increased for BP (42.20 mN/m) and SBP (43.77 mN/m). MTBS values for groups BP (21.3 MPa), SBP (31 MPa), MDPP (30.1 MPa) and SBMDPP (32.3 MPa) were significantly higher in specimens treated with NTP than their untreated counterparts B (9.1 MPa), SB (14.4 MPa), MDP (17.8 MPa) and SBMDP (24.1 MPa). Conclusions (1) Increase of O and decrease of C led to higher surface energy levels dictated by the polar component after NTP; (2) NTP application increased MTBS values of Y-TZP surfaces.

Objectives: This study evaluated the marginal misfit and microleakage of cement-retainedimplant-supported crown copings.Methods: Single crown structures were constructed with: (1) laser-sintered Co–Cr (LS); (2)vacuum-cast Co–Cr (CC) and (3) vacuum-cast Ni–Cr–Ti (CN). Samples of each alloy groupwere randomly luted in standard fashion onto machined titanium abutments using: (1) GCFuji PLUS (FP); (2) Clearfil Esthetic Cement (CEC); (3) RelyX Unicem 2 Automix (RXU) and (4)DentoTemp (DT) (n = 15 each). After 60 days of water ageing, vertical discrepancy was SEM-measured andcementmicroleakage wasscoredusingadigitalmicroscope.Misfit dataweresubjected to two-way ANOVA and Student–Newman–Keuls multiple comparisons tests.Kruskal–Wallis and Dunn’s tests were run for microleakage analysis (a = 0.05).Results: Regardless of the cement type, LS samples exhibited the best fit, whilst CC and CNperformed equally well. Despite the framework alloy and manufacturing technique, FP andDT provide comparably better fit and greater microleakage scores than did CEC and RXU,which showed no differences.Conclusions: DMLSofCo–Crmaybeareliablealternativetothecastingofbasemetalalloystoobtain well-fitted implant-supported crowns, although all the groups tested were within theclinically acceptablerangeofverticaldiscrepancy.Nostrongcorrelationswerefoundbetweenmisfit and microleakage. Notwithstanding the framework alloy, definitive resin-modifiedglass-ionomer (FP) and temporary acrylic/urethane-based (DT) cements demonstrated com-parably better marginal fit and greater microleakage scores than did 10-methacryloxydecyl-dihydrogen phosphate-based (CEC) and self-adhesive (RXU) dual-cure resin agents.# 2012 Elsevier Ltd. All rights reserved.* Corresponding author at: Department of Buccofacial Prostheses, Faculty of Odontology, Complutense University of Madrid (UCM), Pza.Ramo´n y Cajal, s/n, 28040 Madrid, Spain. Tel.: +34 607367903; fax: +34 913942029.E-mail addresses: raquel.castillo@odon.ucm.es (R. Castillo-Oyagu¨e), lynchCD@cardiff.ac.uk (C.D. Lynch), jflozano@odon.ucm.es(J.F. Lo´pez-Lozano), danieltl@us.es (D. Torres-Lagares), mjsuarez@odon.ucm.es (M.-J. Sua´rez-Garci´a).

Objectives To prospectively evaluate the clinical long-term outcome of tooth-supported crowns (SCs), implant-supported crowns (ISCs), and fixed dental prostheses (FDPs) made of a lithium-disilicate glass-ceramic framework material (IPS Empress 2). Materials and methods Between 1997 and 1999, a total of 184 restorations (106 SCs, 32 ISCs, 33 FDPs, and 13 diverse restorations) were placed in 73 patients. Kaplan-Meier estimation was applied for survival and chipping-free rates. Inter-group comparison of both rates was realized by a log rank test and a 2 × 2 contingency table. Also, SCs and FDPs were compared regarding adhesive vs. conventional cementation, and anterior vs. posterior positioning, for impact on survival. Results Due to 14 dropouts (34 restorations) and reasonable exclusion of 19 other restorations, the final dataset included: i) 87 SCs [37 patients, mean observation time 11.4 (±3.8) years]; ii) 17 ISCs [12 patients, mean observation time 13.3 (±2.3) years; and iii) 27 FDPs [19 patients, mean observation time 8.9 (±5.4) years]. The 10-year survival rate/chipping-free rate for SCs were 86.1%/83.4%, for ISCs 93.8%/94.1%, and for FDPs were 51.9%/90.8%. Both ISCs and SCs had a significantly higher survival than FDPs (ISCs vs. FDPs: both tests p = 0.001; SCs vs. FDPs: p = 0.001 and p = 0.005). Differences in the chipping-free rates did not reach significance. Also, neither the cementation mode nor positioning of the restoration had an impact on survival. Conclusions SCs had a slightly lower outcome than can generally be expected from single crowns. In contrast, ICSs had a favorable outcome and the FDPs predominantly failed. Clinical significance The practitioner’s choice of dental materials is based (at best) on long-term experience. The present 10-year results are based on comprehensive data analyses and show the high potential of lithium-disilicate as a reliable material, especially for single-unit restoration.

Objectives To evaluate the influence of different protocols for resin cement removal during cementation on biofilm formation. Methods Twenty-eight ceramic blocks, which were injected under pressure, were placed over enamel blocks obtained from freshly extracted bovine incisors. The ceramic blocks were cemented to the enamel blocks using a dual-cured resin cement and the excess resin was removed according to the experimental group: TS: Teflon spatula; BR: brush; BR+: brush and polishing; SB+: scalpel blade and polishing. After autoclaving, the samples were colonised by incubation in a sucrose broth suspension standardised with Streptococcus mutans in microaerophilic stove. Specimens were quantitatively analysed for bacterial adherence at the adhesive interface using confocal laser scanning microscopy and counting the colony forming units, and qualitatively analysed using SEM. The roughness (Ra/Rz/RSm) was also analysed. Data were analysed by 1-way ANOVA and Tukey's test (5%). Results The roughness values ranged from 0.96 to 1.69 μm for Ra ( p > 0.05), from 11.59 to 22.80 μm for Rz ( p = 0.02 p = 0.00). Bacterial adhesion varied between 1,974,000 and 2,814,000 CFU/ml ( p = 0.00). Biofilm mean thickness ranged from 0.477 and 0.556 μm ( p > 0.05), whilst the biovolume values were between 0.388 and 0.547 μm 3 /μm 2 ( p = 0.04). Lower values for roughness, bacterial adhesion, biofilm thickness and biovolume were found with BR, whilst TS presented the highest values for most of the parameters. SEM images confirmed the quantitative values. Conclusions The restoration margin morphology and interface roughness affects bacterial accumulation. The brush technique promoted less bacterial colonisation at the adhesive interface than did the other removal methods. Clinical significance The brush technique seems to be a good option for removing the excess resin cement after adhesive cementation in clinical practice, as indicated by its better results with lower bacterial colonisation.

The aim of this study was to evaluate the internal adaptation and marginal properties of ceramic laminate veneers fabricated using pressable and machinable CAD/CAM techniques.40 ceramic laminate veneers were fabricated by either milling ceramic blocks using a CAD/CAM system (group 1 n=20) or press-on veneering using lost wax technique (group 2 n=20). The veneers were acid etched using hydrofluoric acid, silanated, and cemented on their corresponding prepared teeth. All specimens were stored under water (37 °C) for 60 days, then received thermocycling (15,000 cycles between 5 and 55 °C and dwell time of 90 s) followed by cyclic loading (100,000 cycles between 50 and 100 N) before immersion in basic fuchsine dye for 24 h. Half of the specimens in each group were sectioned in labio-lingual direction and the rest were horizontally sectioned using precision cutting machine (n=10). Dye penetration, internal cement film thickness, and vertical and horizontal marginal gaps at the incisal and cervical regions were measured (α=0.05).Pressable ceramic veneers demonstrated significantly lower (F=8.916, P0.005) vertical and horizontal marginal gaps at the cervical and incisal margins and lower cement film thickness (F=50.921, P0.001) compared to machinable ceramic veneers. The inferior marginal properties of machinable ceramic veneers were associated with significantly higher microleakage values.Pressable ceramic laminate veneers produced higher marginal adaptation, homogenous and thinner cement film thickness, and improved resistance to microleakage compared to machinable ceramic veneers.The manufacturing process influences internal and marginal fit of ceramic veneers. Therefore, dentist and laboratory technicians should choose a manufacturing process with careful consideration.

Objectives To evaluate the effect of the length of fibre-posts 1 and type of adhesive cement 2 on the fracture resistance of endodontically treated teeth, after fatigue loading. Methods Eighty extracted upper pre-molars were sectioned at the CEJ and endodontically treated. After 24 h of water storage at 37 °C, RelyX Posts (3M-ESPE) were cemented with Panavia F 2.0 (Kuraray) or RelyX Unicem (3M-ESPE). A standardized composite core was built. Specimens were divided into four groups depending on the post–core ratio: (A) 2/1 (control); (B) 3/2; (C) 1/1 (small diameter); (D) 1/1(large diameter) and submitted to 1,200,000 cycles using a chewing simulator (Willytech). Immediately afterwards, all specimens that survived fatigue loading were fractured using a universal loading device (Micro-tester, Instron). Data were analysed with ANOVA. Results Four percent of the specimens failed during fatigue loading. The length of the post into the root affected the fracture resistance. The statistical outcome varied according to the inclusion of specimens failed during fatigue loading. However, the control group always had the lowest fracture resistance. The type of adhesive cement did not affect the fracture resistance. A prevalence of not-repairable failures was observed in specimens restored with the longest posts, whilst shorter posts led to more repairable failures. Conclusions Shortening the post length and the ensuing preservation of more tooth structure, offer the potential for reparability through an in-built fail safe mechanism and may thus reduce the occurrence of catastrophic failures.

The effect of heat-pressing and subsequent pre-cementation (acid-etching) and resin-cementation operative techniques on the development of transient and residual stresses in different thicknesses of a lithium disilicate glass-ceramic were characterised using profilometry prior to biaxial flexure strength (BFS) determination.60 IPS e.max Press discs were pressed and divested under controlled conditions. The discs were polished on one surface to thicknesses of 0.61±0.05, 0.84±0.08, and 1.06±0.07 mm (Groups A-C, respectively). The mean of the maximum deflection (acid-etching and resin-coating was determined using high resolution profilometery prior to BFS testing. Paired sample t-tests were performed (p0.05) on the 20 individual samples in each group (Groups A-C) for each comparison. Differences between the baseline quantification and resin-cement coating deflection values and BFS values for Groups A-C were determined using a one-way ANOVA with post hoc Tukey tests (p0.05).Baseline quantification for Groups A-C identified no significant differences between the group means of the maximum deflection values (p=0.341). Following HF acid-etching, a significant increase in deflection for all groups (p0.001) was identified compared with the baseline quantification. Additionally, resin-cement coating significantly increased deflection for Group A (p0.001), Group B (p0.001) and Group C (p=0.001) specimens for the individual groups. The increased deflection from baseline quantification to resin-cement coating was significantly different (p0.001) for the three specimen thicknesses, although the BFS values were not.The lower reported baseline quantification range of the mean of the maximum deflection for the IPS e.max(®) Press specimens was predominantly the result of specimen polishing regime inducing a tensile stress state across the surface defect integral which accounted for the observed surface convexity. Acid-etching and resin-cementation had a significant impact on the development and magnitude of the transient and residual stresses in the lithium disilicate glass-ceramic investigated.

Objectives The purpose of this prospective study was to evaluate the clinical outcome of inlay-retained fixed dental prostheses (IRFDPs) with a new design made from a zirconia ceramic. Methods Twenty-three 3-unit IRFDPs were placed in 23 patients, restoring five second premolars and 18 first molars. Preparations were performed in accordance with general principles for ceramic inlay restorations and modified with a retainer-wing bevel preparation in the enamel at the buccal and oral sides. The frameworks were scanned and milled out of zirconia ceramic, using the InLab CAD/CAM-system and the pontics were veneered with feldspathic ceramic. All IRFDPs were luted adhesively with composite resin. Clinical follow-up examinations were performed annually. Statistical analysis was performed using descriptive statistics and Kaplan–Meier survival analysis. Results All patients with their 23 IRFDPs could be examined clinically after a mean observation time of 20 months. None of the IRFDPs failed. Two ceramic veneers fractured, both of them needed repair. One restoration debonded, but was recemented immediately. However, these technical complications did not affect the clinical function of the IRFDPs involved. Conclusions The clinical outcome of zirconia ceramic IRFDPs with the modified design seems promising.

The purpose of this study was to evaluate the fracture loads of post-and-core systems with two different individually formed fibre post designs and polymerization conditions.Totally seventy-two (n=8/group) bovine teeth were cut and made up the root length of 15.0mm. They were divided into 3 main groups (Group A, B, C). A: one glass fibre post was light-cured before cementation, B: fibres were bundled to fill the entire root canal opening and light-cured before cementation, C: one unpolymerized glass fibre post was inserted into cement-filled root canal and light-cured with luting cement (ParaCem). Moreover specimens of each group were divided into 3 subgroups according to the post length: subgroup 1: 10mm; subgroup 2: 7.5mm; subgroup 3: 5.0mm. After cementation, the core was built up, and then made the composite resin crown (Filtek Z250). Fabricated specimen was loaded from 45° of palatal side at a crosshead speed of 1.0mm/min. The first load drop and maximum fracture loads were statistically analyzed by ANOVA and Tukey's test.Maximum fracture load of Group B (433 N) and C (418 N) are significantly higher than Group A (284 N) (p0.01). Short post (5mm) provided higher fracture loads in all main groups, especially in Group C.Using short and thick fibre post system (the same diameter as the root canal) showed higher strength than one fibre post only. In addition, by curing the cement and the fibre material simultaneously, the strength of the restored tooth was increased.

The aim of the present study was to evaluate the ormocer Definite (Degudent, Hanau, Germany) as resin luting cement.In a controlled prospective clinical study, 57 Cergogold (Degudent) all-ceramic inlays were placed in 24 patients by four dentists. The restorations were luted with two different systems (MD=Definite Multibond+Definite; SV=Syntac+Variolink Ultra, Ivoclar Vivadent, Liechtenstein) without lining. At baseline, after 12, 24, and 48 months, restorations were examined according to modified USPHS scores and criteria.One patient including three restorations missed the 4 years recall (dropout). After 48 months of clinical service, four restorations in four patients (three luted with Definite, one with Variolink) failed due to inlay fracture (n=3) and tooth fracture (n=1), all other fillings were clinically acceptable (survival rate 93.3% for Definite vs. 95.2% for Variolink; Kaplan-Meier algorithm). Except for the rate of hypersensitivity at baseline (MD: 27%; SV 0%; p0.05), no differences were evident between the luting cements at any recalls (Mann-Whitney U-test; p0.05). Between the four recalls, a statistically significant deterioration was detected for both groups regarding the criteria marginal adaptation, filling integrity (cracks/chippings/fractures), and tooth integrity (Friedman test; p0.001). After 4 years, mainly distinct deterioration with marginal fractures or chippings in proximal and marginal areas of the inlays were observed. No differences were found for surface roughness, color matching, and proximal contact (p0.05).For luting of ceramic inlays, only slight differences between the two luting systems were detectable.

Aim It is the aim of this paper to consider the treatment instituted when re-intervention is deemed necessary on a tooth which has previously been crowned. Methods A detailed sample of treatment records of patients has been established at the NHS Business Services Authority (Dental Services Division), consisting of records containing indirectly placed restorations for patients of age 18 years or older from January 1991. For each tooth treated with a crown, the subsequent history of intervention on that tooth was recorded. Results There were data on 47,474 crowns available for analysis, with metal-ceramic (bonded) crowns dominating the data (overall, 80% of crowns being these). There were 10,426 crowned teeth with re-interventions in the study period, with 36% of the re-interventions involving recementing, 17% being replacement crowns, 13% direct restorations, 12% root treatment, and 19% of crowned teeth being extracted and/or replaced by a denture. The longer the interval since crown placement, the higher the proportion of extractions or direct restoration and the lower the proportion of recementing. Conclusions Recementation is the most frequently recorded re-intervention, with the incidence of this decreasing with increasing age of the crown. In 17% of re-interventions, the next intervention was a replacement crown.

Objectives This study aimed to investigate the influence of the occlusal form variation of a single molar crown on the smoothness of masticatory movement. Methods The subjects included 19 adults who visited the hospital seeking a single prosthetic restoration on a molar. Three types of crown were used: (i) an anatomical form, (ii) a flat occlusal table with occlusal contacts and (iii) a flat occlusal table without occlusal contacts. All restored the proximal contacts, and were temporarily cemented in random order. One week after each crown was cemented, the jaw movement trajectory was recorded during gum chewing and the normalized jerk-cost (NJC) was calculated for each chewing cycle. The mean and standard deviation of the chewing rhythms, pathways and peak speeds, were also calculated. Results Restoration by the anatomical occlusal form crown significantly decreased the standard deviation of the parameters for the chewing rhythm. The jerk analysis showed a significant NJC decrease after all types of crown were placed on the treated side. The smoothness of masticatory movement was more improved in the subjects who received each type of crown on their mandibular molar than those on the maxillary molar. Conclusions These results suggest that achieving occlusal and proximal contacts by a single crown treatment is associated with a reduction in the variability of jaw movements. These findings confirm the clinical importance of restoring occlusal contacts and proximal contacts even for a single tooth.

Objectives This study investigates the biomechanical interactions among restorative materials, cuspal preparation designs, and cement thickness in a cusp-replacing adhesive premolar restoration. Methods Twenty-seven, 3D finite element (FE) models designed in a typical MODL restoration with three restorative materials (CAD/CAM ceramic block, indirect resin composite and glass-ceramic), three cavity preparation designs (buccal cuspal reduction of 1.0 mm, 1.5 mm and 2.0 mm in cuspal height) and three cement thicknesses (50 μm, 100 μm and 150 μm) were constructed to perform the simulations. The ANOVA test was performed to determine the relative importance of the investigated factors and main effects for each of the three investigated factor levels (restorative material, preparation design and cement thickness) in terms of the principal stress values. Results The results indicated that the stress value in the restorative material was influenced primarily by the restorative material itself (95.49%). Preparation design was found as the major factor (>80%) affecting the stress values in the remaining tooth and luting cement. Conclusions Using a low modulus restorative material presented more favorable biomechanical performance and the cuspal height might be at least 1.5 mm to critically reduce the stress values when cuspal-coverage treatment is considered. The investigated cement thickness only slightly affected the mechanical behavior of the cuspal replacement restoration.

Objective: The aim of this study was to investigate the influence of a fiber post on the fracture mechanics of zirconia crowns inserted over endodontically treated teeth with different extent of coronal damage.Methods: Endodontically treated human molars with three types of coronal damage received fiber posts before cementation of zirconia-veneered crowns. Controls received composite resin cores without fiber posts. The specimens were loaded to failure and fractographically examined using a scanning electron microscope (SEM).Results: Statistical analysis revealed that specimens with fiber posts demonstrated significantly higher failure loads and favorable fracture pattern compared to the controls. At fractographic analysis, specimens with fiber posts demonstrated delamination of the veneer ceramic from intact zirconia under structure. Meanwhile, the specimens that were restored without a fiber post demonstrated micro-cracking of the composite core build-up resulting in loss of the support under the zirconia crowns which was responsible for the initiation of radial crack and catastrophic damage.Conclusions: Within the limitation of this study, the insertion of fiber post improved the support under zirconia crowns which resulted in higher fracture loads and favorable failure type compared to composite core build-up.

The aim of this retrospective longitudinal study was to evaluate the clinical long-term survival of telescopic crown retained removable partial dentures (TRPDs), the influencing factors on survival as well as the type and number of necessary treatments during the observation time.The study is based on the data of 463 patients who had received a total of 554 TRPDs with a total of 1758 telescopic crowns between 1995 and 2004 in our Dental School. The influence of the patient's gender, location of the denture, number of abutment teeth per telescopic denture, their distribution (Kennedy-class) and the impact of a routinely follow-up programme on the survival probability were analysed.During the observation period (mean 5.3+/-2.9 years) 4.7% of the TRPDs ceased functioning and 3.8% of the abutment teeth were extracted. The survival probability after 5 years was 95.1% for the TRPDs and 95.3% for the abutment teeth. No denture with more than four abutments required replacement. Only the covariates number of abutment teeth and patient in-follow-up showed a significant (p0.01) influence on the survival probability. 26.9% of the TRPDs needed facing repairs, 34.8% relines, 20.6% loss of cementation of a primary crown and 1% abutment tooth treatment.Within the limits of a retrospective study it can be concluded that the number of attachments and thorough aftercare have a considerable impact on the long-term success of TRPDs. Though loss of cementation and defects of the facings were significant in number, they did not endanger the long-term success of a TRPD at all.

Summary Objectives. The performance of both light-curing and dual-cured adhesive/luting systems (as control), when used in combination with translucent fibre posts, was evaluated by means of pull-out test and scanning electron microscopy (SEM ) observation. Methods. Forty root canal treated teeth were randomly divided into two groups of 20 specimens each. Group 1 light-curing system: Excite and Tetric Flow; Group 2 dual cured system: All Bond 2+RelyX ARC. Translucent, double taper fibre posts were used (2.1/1.4 mm diameter). The teeth were stored in NaCl 0.9% solution at 37 °C. A week later, the pull-out test was carried out on all specimens. Ten tested specimens for each group and their corresponding posts were processed for SEM observation. Statistical analysis was performed applying one-way analysis of variance (ANOVA) followed by T-test as post-hoc comparison at a significance level set at p Results. There is no statistically significant difference (p>0.05) between the light-curing system group (275.2±58.9 N) and the dual cured one (301.4±40.1 N). SEM observations confirm a good bond between the dentine and the post whatever the curing method employed. Conclusions. Dual curing of the All Bond 2+RelyX ARC system seems to be the most appropriate method since it allows to cure even those areas which would not be otherwise reached by light. On the other hand, in apical areas, the incomplete curing of the Excite+Tetric Flow system could improve the post adaptation and allow the achievement of both an improved apical seal and a more even distribution of the stress along the canal walls.

Summary Objective. The aim of this study was to determine whether a dentine bonding agent (DBA) had an effect in reducing fluid filtration under cemented provisional crowns. Methods. Crown preparations on 34 premolars, randomly allocated to two equalsized test and control groups, were assessed for dentine permeability by a fluid filtration technique. In the test group, prepared crowns were acid-etched and then treated with a DBA (Prime & Bond NT). In the control group, no such DBA was applied. Provisional crowns were cemented on both groups of teeth using non-eugenol zinc oxide cement. Fluid filtration rates were measured repeatedly after crown preparation, at cementation, 1 h, 1 day, 1 week and 3 weeks following crown cementation for both groups. Filtration rates were also measured after acid-etching and dentine bonding for the test group. Results. There was insufficient evidence to suggest any statistically significant differences either between the two groups or, on average, across the five time points in each group in terms of the relative percentage of fluid filtration. Conclusion. The DBA used did not seal dentinal tubules any more than did the smear layer and provisional crowns luted with a non-eugenol ZnO cement. q 2004 Elsevier Ltd. All rights reserved.

Objectives To evaluate the long-term survival and complication rates of posterior three-unit fixed dental prostheses (FDPs) fabricated from a glass-infiltrated zirconia reinforced alumina ceramic (In-Ceram Zirconia). Methods Fifty-eight patients received 65 FDPs. Twelve FDPs replaced the second premolar (8 in the maxilla, 4 in the mandible), and 53 replaced the first molar (19 in the maxilla, 34 in the mandible). The In-Ceram Zirconia ceramic frameworks were designed and milled using the Cerec CAD/CAM system. The minimum dimension of the proximal connectors of the frameworks was 12 mm2 and 16 mm2 for premolars and molars, respectively. After milling and glass infiltration, the frameworks were veneered with a feldspathic ceramic. All FDPs were cemented with glass-ionomer cement. The patients were recalled 6–12 months after placement, and then annually. Kaplan–Meier analysis was used to calculate the survival and complication rates of the FDPs. Results The mean observation time was 9.7 years. Six patients with 6 FDPs were regarded as dropouts. Using the Kaplan–Meier method the 10-year cumulative survival rate was 93.6%. In a worst-case scenario, in which the 6 missing FDPs are considered as failed, the 10-year survival rate would be 84.6%. Conclusion Three-unit posterior FDPs made from In-Ceram Zirconia presented a 10-year survival rate similar to that reported for conventional FDPs. However more technical and biological complications were reported. Clinical significance Three-unit posterior FDP made from In-Ceram Zirconia may be a viable treatment modality, taking the strict adherence to the manufacturer's recommendations into consideration.

Objectives: This in vitro study investigated the effect of selected luting media on the fracture resistance of a flame-sprayed all-ceramic crown. Methods: Three groups of 10 human upper premolar teeth were prepared for crowning using a standardised technique. Flame sprayed crowns were fabricated and cemented onto the preparations using zinc phosphate (ZPC), glass polyalkenoate (GPC) or composite luting cement (CLC). During crown seating, a pressure perfusion system simulated pulpal fluid outflow equivalent to 300 mm of H 2 O. Compressive fracture resistance was determined for each group using a Universal Testing Machine with a crosshead speed of 1 mm min −1 . A group of unrestored teeth acted as a control. Results: The fracture resistance of the groups ranked as follows: ZPC>CLC⪢GPC=unrestored teeth. The difference between the fracture resistance of ZPC and CLC groups and the control group was statistically significant. The mode of fracture between the luted crowns and natural crowns was markedly different. Conclusions: When tested in compression, a new, flame-sprayed all-ceramic crown, when luted in place using ZPC, GPC or CLC, could produce strengths comparable to or greater than natural unrestored teeth. The luting agent used significantly affected the recorded fracture loads.

Three types of fiber-reinforced composite (FRC) molar crowns were tested on their fracture resistance and marginal adaptation under simulated oral stress conditions. Two glass fiber systems, one processed with a vacuum/pressure system, the other by manual fiber adaptation, and a polyethylene fiber system were evaluated. Every group consisted of 12 crowns. All crowns were luted adhesively on human molars and exposed to thermal cycling and mechanical loading (TCML: 6000×5°C/55°C; 1.2×10 6 ×50 N; 1.66 Hz). The marginal adaptation was evaluated through dye-penetration and analyzed semi-quantitatively with a scanning electron microscope. The fracture resistance was measured using a Zwick universal testing machine. The highest fracture resistance was observed on the glass-fiber systems (FibreKor/Sculpture 1875 N±596; Vectris/Targis 1726±542), though statistically, the polyethylene system (belleGlass/Connect 1388±620) was not significantly weaker. All systems exceeded the fracture resistance required to withstand the maximum masticatory forces expected in the molar region. The marginal adaptation generally had a tendency towards larger gaps after TCML. The crown/composite-cement bond deteriorated significantly after TCML with the manual fiber adaptation and the polyethylene fiber system. The cement/tooth bond strength depended on which composite-cement/dentin-adhesive system was used. Conclusion: The fracture resistance of molar crowns made of glass-fiber reinforced composite was higher than those of polyethylene fiber-reinforced composite crowns. However, there was no statistically significant difference. The marginal adaptation seems to depend on the fiber systems and composite-cement/dentin adhesive system used.

Objectives: Functional occlusal loading can generate complicated stresses in the luting cement film between a restoration and its abutment. Such stresses may lead to cement fractures, which can promote cement dissolution and induce clinical problems. The purpose of this study is to determine the function of the cement film under loading, and to clarify the relationship between the deformation of the restoration and the cement fractures. Methods: Eccentric loads were applied onto model extension bridges which were cemented on brass dies with zinc phosphate cement. Strain measurements were recorded using of a strain gauge method, ultimate strength by tensile tests, leakage by dye penetration tests and cement fractures by ultrasonic microscopic analyses. Additionally, the bridges which were just seated on their dies without cementation were loaded, and strain measurements were recorded. Results: The cases for linear strain increment with loading showed high tensile strength and minimal dye penetration. The cases with non-linear strain behavior showed low tensile strength and considerable dye penetration. However, no fracture was observed in the occlusal cement film in both cases. The cement fracture first occurred at the opposite marginal region to the loading side. Conclusions: One of the significant functions of the cement film is diminishing the deformation of restorations during loading. The deformation of the restoration affects initiation and propagation of the cement fracture considerably.

Objectives The purpose of this randomized clinical study was to evaluate the clinical performance of posterior, metal-free polymer crowns after follow-up for up to six years, and to compare it with the performance of metal–ceramic crowns. Methods Eighty single crowns, manufactured from a polymer composite resin, were set on posterior teeth. Half of these received a glass–fibre framework (group 1) whereas half were prepared without framework stabilization (group 2). As the control group, 40 conventional metal–ceramic crowns were inserted. Primary endpoints were incidence of complications, investigated on a time-to-event basis, plaque status, and aesthetic performance. Results Thirty clinically relevant complications occurred after a median time of 2.3 years. Median follow-up time was four years. The most frequent complications were delamination ( n = 24) and root-canal treatment ( n = 4) of the crowns; the incidence of complications was not significantly different among crown materials ( p = 0.60). Twenty crowns had to be replaced (six polymer crowns in group 1, nine polymer crowns in group 2, four crowns in the control group, and one tooth (in group 1) had to be extracted). Mean plaque and gingival indexes for the test groups did not differ from those for the control group. Conclusions Within a median follow-up period of four years, the clinical performance of posterior polymer crowns with and without a glass–fibre framework was not significantly different from that of metal–ceramic crowns, although the number of catastrophic failures of composite crowns was higher than that of the metal–ceramic crowns. Clinical significance On the basis of the study results, posterior polymer crowns may be an alternative to metal–ceramic crowns, although additional research is needed before they can be recommended, without reservation, as permanent restorations.

To determine the impact of hypodontia on the quality of life of adolescent and young adult patients, and, to assess the impact of restoring tooth spaces with resin bonded bridgework on quality of life of patients with hypodontia.In a prospective study, 82 patients with a confirmed diagnosis of hypodontia participated. The primary outcome was oral health related quality of life (OHRQoL) and this was measured using the OHIP-49 prior to treatment. The pre-treatment sample was then divided into two groups: the test group (n=40 patients) who had completed orthodontic treatment and had tooth spaces restored with resin bonded bridgework, and, a control group (n=42 patients) who were still in the process of orthodontic treatment. All patients completed a follow-up OHIP-49, and between and within group comparisons made.The pre-treatment sample included 43 females and 39 males, age ranged from 16 to 34 years (median age 19). Forty-three patients had more than 4 congenitally missing teeth and thirty-nine had ≤ 4 congenitally missing teeth. There were no differences between the groups prior to treatment. For the test group, there was a significant improvement in median OHIP summary scores (p0.001) after treatment. OHIP scores deteriorated to a significant degree for control subjects (p=0.002). The effect sizes for the pre-post treatment change in both groups were moderate to large.Hypodontia has a significant impact on oral health related quality of life. Provision of resin bonded bridges has a positive impact on oral health related quality of life of patients with hypodontia.

Objective The aim of this study was to investigate the effect of different luting agents on the bond strength of zirconium oxide posts in root canals after artificial ageing. Material and methods Thirty single-rooted extracted teeth were collected. Post spaces were prepared. Custom milled zirconium oxide posts (Cercon, Degudent) were fabricated. Specimens were divided into 3 groups ( n = 10), according to the luting agents used: group RA, conventional resin luting agent (RelyX ARC); group RU, self-adhesive resin luting agent (RelyX Unicem); and group Z, zinc phosphate luting agent (DeTrey). Specimens were subjected to thermocycling and water storage at 37 °C. Specimens were horizontally sectioned into three sections and subjected to a push-out test with 0.5 mm/min crosshead speed. The failure mode was assessed by scanning electron microscopy. Data were analysed by using 2-way ANOVA. Results The following bond strength values were obtained: group RA – 8.89 MPa, group RU – 10.30 MPa and group Z – 9.31 MPa. There was no significant difference in bond strength among the groups ( P = 0.500). Adhesive failure mode at the cement/post bonded interface was seen in 100%, 66.67% and 83.3% of examined sections in groups RA, RU and Z, respectively. There was no significant difference in bond strength among different root regions ( P = 0.367). Conclusion The type of luting agent had no significant effect on the push-out bond strength of zirconium oxide posts after artificial ageing. Clinical significance Conventional luting agents, such as zinc phosphate cement, seem to provide comparable retention to resin luting agents for cementing custom milled zirconium oxide posts.

Objectives To evaluate the incidence of prosthetic complications in implant-retained crowns made with UCLA castable abutments and to identify possible risk factors with a view to establishing recommendations to help predict the success of such restorations. Methods A cohort follow-up study was carried out in 71 partially dentate patients rehabilitated with 93 implant-retained single crowns. Data regarding socio-demographic background, anatomical features, implant-, and prosthesis-related variables were recorded. The incidence rate (%), relative risk (RR) and odds ratio (OR) were applied for predictive risk factors. ANOVA and Student t-tests were used to compare quantitative variables, the chi-square test was used to compare proportions and also a logistic regression analysis was performed. The statistical significance was set at α = 0.05. Results Two implants (2.2%) were lost during the first year of function. The incidence of prosthetic complications in the observed mean period (26.2 ± 15.4 months) was 11.9%, consisting of screw loosening (10.8%) and ceramic fracture (1.1%). A higher tendency for prosthetic complications was noticed in posterior mandibular crowns restoring saddles longer than 10 mm with mesiodistal cantilevers longer than 6 mm, having natural antagonists, after long-term use (>20 months), with initial torque values superior than 30 Ncm. Conclusions Screw loosening is the most frequent complication in implant-retained crowns fabricated with UCLA abutments cast in cobalt–chromium. Nevertheless, the connection usually remains stable after retightening the screws. A high survival rate was recorded, and these prostheses may be a suitable treatment option. Clinical significance Based on the study findings, the risk of prosthetic complications is expected to increase when long-span posterior edentulous areas are rehabilitated with single implant-supported crowns. The antagonist occlusal plane should be restored to prevent torsional forces and overloading. Implant systems with initial torque values less than 30 Ncm should be selected.

The purpose of this study was to evaluate the influence of internal-gap width and cement type on the retentive force of zirconia copings.A CAD/CAM system was used to mill 48 identical abutments on extracted human molars and fabricate 48 zirconia copings. The internal-gap width for cement was set to 40 μm or 160 μm (n=24 each). Three cement types (Panavia F, RelyX Unicem, and RelyX Luting) were used with each internal-gap width (n=8/cement type). The intaglio surfaces of the copings were airborne-particle abraded, and each coping was cemented onto the corresponding abutment using the indicated luting agent. After 10,000 cycles of thermocycling, the retentive force was evaluated by pullout tests. Kruskal-Wallis and Wilcoxon Rank Sum tests were used for data analysis (α=0.05).In the 40-μm gap groups, Panavia F had the highest mean retentive force compared to RelyX Unicem and RelyX Luting (P0.000). In 160-μm gap groups, RelyX Unicem had the highest mean retentive force compared to Panavia F and RelyX Luting (P0.000).With the increase in internal gap width, a resin cement with self-etching agents as a co-initiator for autopolymerization resulted in significantly decreased retentive force, whereas a resin-modified glass ionomer cement or a self-adhesive resin cement did not. Use of resin cements rather than resin-modified glass ionomer cements improved the retentive force of zirconia copings regardless of the amount of internal gap width.

To determine how the variability in biaxial flexure strength of a soda-lime glass analogue for a PLV and DBC material was influenced by precementation operative variables and following resin-cement coating.The flexural modulus of a transparent soda-lime glass was determined by longitudinally sectioning into rectangular bar-shaped specimens and the flexural moduli of three resin-based materials (Venus Flow, Rely-X Veneer and Clearfil Majesty Posterior) was also determined. Disc shaped soda-lime glass specimens (n=240) were divided into ten groups and were alumina particle air abraded, hydrofluoric (HF) acid-etched and resin-cement coated prior to biaxial flexure strength testing. Sample sets were profilometrically evaluated to determine the surface texture. One-way analyses of variance (ANOVA) and post hoc all paired Tukey tests were performed at a significance level of P0.05. The mean biaxial flexure strengths were plotted against resin-coating thickness and a regression analysis enabled estimation of the 'actual' magnitude of strengthening.The mean three-point flexural modulus of the soda-lime glass was 40.0 (1.0)GPa and the Venus Flow, Rely-X Veneer and Clearfil Majesty Posterior were 3.0 (0.2)GPa, 6.0 (0.2)GPa and 14.8 (1.6)GPa, respectively. At a theoretical 'zero' resin-coating thickness an increase in biaxial flexure strength of 20.1% (63.2MPa), 30.8% (68.8MPa) and 36.3% (71.7MPa), respectively was evident compared with the control (52.6 (5.5)MPa).Disc-shaped specimens cut from round stock facilitated rapid fabrication of discs with uniform surface condition and demonstrated strength dependence was influenced by precementation parameters and resin-cementation variables.

Objectives Chlorhexidine preserves the long-term bonding between composite restorations and coronal dentine. Our aim was to evaluate the long-term effect of chlorhexidine on attachment of fibre-reinforced composite (FRC) root canal posts to root canals. We hypothesized that chlorhexidine would not negatively affect the bond strength in aged specimens. Methods Root canals of 40 human extracted third molars were prepared for post cementation with each post systems’ own burs. Four commercially available FRC posts (Glassix, D.T. Light-Post, Unicore, everStickPOST) were cemented with three different cements (Duo-link, PermaFlo DC, RelyX Unicem). After etching, except with self-adhesive RelyX Unicem, the post spaces were irrigated either with 2% chlorhexidine (Consepsis) or physiological saline for 60 s. The roots (n = 5 per group) were cut into 2 mm thick dentine discs. The discs were stored in artificial saliva for one year. The bond strength was measured with the push-out method, and the failure mode was evaluated with a stereomicroscope. Results Unicore with PermaFlo DC and everStickPOST with RelyX Unicem demonstrated significantly higher bond strength values both with and without chlorhexidine. After one year of storage chlorhexidine application improved the bond strength with D.T. Light-Post/Duo-link. With other posts and cements chlorhexidine application did not affect the bond strength. Conclusion 2% chlorhexidine did not negatively affect the long-term bond strength of any material tested. Clinical significance Irrigation of root canals with chlorhexidine, as indicated to prevent root canal infection during post placement, does not interfere with post bond strength when FRC posts are used.

Made available in DSpace on 2013-09-27T14:54:24Z (GMT). No. of bitstreams: 1 WOS000300954900003.pdf: 1313835 bytes, checksum: 0cf6593daf3d53269ce8417dfdc097ae (MD5) Previous issue date: 2012-04-01 Made available in DSpace on 2013-09-30T18:34:55Z (GMT). No. of bitstreams: 1 WOS000300954900003.pdf: 1313835 bytes, checksum: 0cf6593daf3d53269ce8417dfdc097ae (MD5) Previous issue date: 2012-04-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T14:05:10Z No. of bitstreams: 1 WOS000300954900003.pdf: 1313835 bytes, checksum: 0cf6593daf3d53269ce8417dfdc097ae (MD5) Made available in DSpace on 2014-05-20T14:05:10Z (GMT). No. of bitstreams: 1 WOS000300954900003.pdf: 1313835 bytes, checksum: 0cf6593daf3d53269ce8417dfdc097ae (MD5) Previous issue date: 2012-04-01 Brazilian Government Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) National Science Foundation Objectives: Because fibre post restorations are influenced by multiple factors such as the types of bonding materials, the dentine region and the time under moist exposure, this study sought to determine the bond strength of endodontic restorations and its relation to the degree of conversion of the cement layer and the molecular structure of the dentine-bonded joints.Methods: The performance of 2 etch-and-rinse (All-Bond 2 and One-Step Plus) and 2 self-etch (Clearfil SE Bond and Xeno III) adhesives at post spaces regions, after 7 d or 4 m, was evaluated. FRC Postec Plus posts were cemented to the root canal with a dual-cure resin cement (Duo-Link). Transverse sections of the tooth were subjected to push-out testing, to degree-of-conversion measurements and to hybrid layer evaluation through mu-Raman spectroscopy.Results: Coronal bonding was higher than cervical and middle bonding. The hybrid layer was thicker for the etch-and-rinse systems, with thicknesses decreasing towards the middle region. The degree of conversion measured for the 3-step etch-and-rinse group after 4 m was significantly higher than that for the self-etching groups.Conclusions: Although not totally stable at the adhesive-dentine interface, the 3-step etch-and-rinse adhesive in the coronal dentine provided the best bond strength, degree of conversion of the cement and hybrid layer thickness in post restorations, in both short- and long-term analyses. (C) 2012 Elsevier Ltd. All rights reserved. São Paulo State Univ, Dept Dent Mat & Prosthodont, São Paulo, Brazil Inst Aerosp Technol, Elect Engn Div, São Paulo, Brazil Princeton Univ, Dept Aerosp Engn, Princeton, NJ 08544 USA São Paulo State Univ, Dept Dent Mat & Prosthodont, São Paulo, Brazil FAPESP: 05/59205-4 CAPES BEX 0031-07-0 National Science Foundation: DMR 0231418

This study aimed to evaluate the vertical misfit and microleakage of laser-sintered and vacuum-cast cement-retained implant-supported frameworks.Three-unit implant-fixed structures were constructed with: (1) laser-sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Pd-Au (CP). Every framework was luted onto 2 prefabricated abutments under constant seating pressure. Each alloy group was randomly divided into three subgroups (n=10) according to the cement used: (1) Ketac Cem Plus (KC); (2) Panavia F 2.0 (PF); and (3) RelyX Unicem 2 Automix (RXU). After 30 days of water ageing, vertical discrepancy was measured by SEM, and marginal microleakage was scored using a digital microscope. Three-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, FDP retainer, and cement type on vertical misfit. Data for marginal microleakage were analysed with Kruskal-Wallis and Dunn's tests (α=0.05).Vertical discrepancy was affected by alloy/manufacturing technique and cement type (p0.001). Despite the luting agent, LS structures showed the best marginal adaptation, followed by CP, and CC. Within each alloy group, KC provided the best fit, whilst the use of PF or RXU resulted in no significant differences. Regardless of the framework alloy, KC exhibited the highest microleakage scores, whilst PF and RXU showed values that were comparable to each other.Laser-sintered Co-Cr structures achieved the best fit in the study. Notwithstanding the framework alloy, resin-modified glass-ionomer demonstrated better marginal fit but greater microleakage than did MDP-based and self-adhesive dual-cure resin cements. All groups were within the clinically acceptable misfit range.Laser-sintered Co-Cr may be an alternative to cast base metal and noble alloys to obtain passive-fitting structures. Despite showing higher discrepancies, resin cements displayed lower microleakage than resin-modified glass-ionomer. Further research is necessary to determine whether low microleakage scores may guarantee a suitable seal that could compensate for misfit.

The aim of this study was to evaluate four methods of Try-in paste removal from a lithium disilicate ceramic surface before cementation and assess the influence on bond strength to a resin luting cement.Slices of dentine (1.6mm thick) were sectioned from the crown of human third molars and truncated cone shape cavities were made with diamond burs. IPS e.max Press ceramic blocks were obtained for each cavity, etched with hydrofluoric acid and fixed with temporary paste, except for Group G1, which was cemented according to the manufacturer's instructions. Try-in paste was removed from the experimental groups using different techniques: G2, ultrasonic bath in distilled water (5 min); G3, air/water spray (1 min); G4, etched with phosphoric acid (2 min)+air/water spray (30 s) and G5, etched with phosphoric acid before and after hydrofluoric acid application+air/water spray (30s). The ceramic restorations were cemented with the same procedures as G1. Push-out bond strength testing (MPa) was performed in a universal testing machine with a crosshead speed of 0.5mm/min.One way ANOVA and Tukey's test (P0.05) were applied: G4(19.21)a, G2(17.09)ab, G1(16.82)ab, G3(16.18)ab and G5(15.9)b. The results showed that all of the experimental groups showed remaining particles of Try-in paste. The bond strength in G4 was statistically higher than in G5. No significant difference was shown in the other groups. There was a predominance of adhesive failures between resin cements and ceramics in G5.The techniques used were not totally effective at removing the Try-in paste; however, the presence of remaining material did not influence the bond strength of restorations. The methods of temporary paste removal may affect the bond strength of ceramic restorations.

This study tested the hypothesis that bond strength of total- and self-etching adhesive systems to dentine is not affected by the presence of remnants from either eugenol-containing (EC) or eugenol-free (EF) temporary cements after standardized cleaning procedures.Thirty non-carious human third molars were polished flat to expose dentine surfaces. Provisional acrylic plates were fabricated and cemented either with EC, EF or no temporary cements. All specimens were incubated for 7 days in water at 37°C. The restorations were then taken out and the remnants of temporary cements were mechanically removed with a dental instrument. The dentine surfaces were cleaned with pumice and treated with either total-etching (TE) or self-etching (SE) dental adhesive systems. Atomic force microscopy was used to examine the presence of remnants of temporary cements before and after dentine cleaning procedures. Composite resin build-ups were fabricated and cemented to the bonded dentine surfaces with a resin luting cement. The specimens were then sectioned to obtain 0.9mm(2) beams for microtensile bond strength testing. Fractographic analysis was performed by optical and scanning electron microscopy.ANOVA showed lower mean microtensile bond strength in groups of specimens treated with EC temporary cement than in groups treated with either no cement or an EF cement (p0.05). Mean microtensile bond strength was lower in groups employing the SE rather than the TE adhesive system (p0.001). SE samples were also more likely to fail during initial processing of the samples. There was no evidence of interaction between cement and adhesive system effects on tensile strength. Fractographic analysis indicated different primary failure modes for SE and TE bonding systems, at the dentine-adhesive interface and at the resin cement-resin composite interface, respectively.The use of eugenol-containing temporary cements prior to indirect bonding restorations reduce, to a statistically similar extent, the bond strength of both total- and self-etching adhesive systems to dentine.