Survival of anterior cantilevered all-ceramic resin-bonded fixed dental prostheses made from zirconia ceramic

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.     

Randomized clinical trial on single retainer all-ceramic resin-bonded fixed partial dentures: Influence of the bonding system after up to 55 months

Objectives

This study evaluated the clinical outcome of all-ceramic resin-bonded fixed partial dentures (RBFPDs) with a cantilevered single-retainer design.

Methods

Thirty anterior zirconia ceramic RBFPDs were inserted using either a phosphate monomer containing resin (Panavia 21 TC; N = 16) or an adhesive bonding system with a phosphoric acid acrylate primer (Multilink–Automix with Metal/Zirconia primer; N = 14).

Results

During a mean observation time of 41.7 months one debonding occurred in each group. Both RBFPDs could be rebonded successfully resulting in a three-year survival rate of 100%.

Conclusion

Independent of the bonding system cantilevered zirconia ceramic RBFPDs showed promising results during the first three years.

Clinical significance

Single-retainer zirconia ceramic RBFPD present an alternative treatment option offering good aesthetics, a minimal invasive preparation, a high biocompatibility and can even be used to treat juvenile patients who do not yet come into consideration for implant placement. No significant influence of the bonding system used was detected so far.     

Two year clinical evaluation of a low-shrink resin composite material in UK general dental practices

Objective

A novel resin composite system, Filtek Silorane (3M ESPE) with reduced polymerization shrinkage has recently been introduced. The resin contains an oxygen-containing ring molecule (‘oxirane’) and cures via a cationic ring-opening reaction rather than a linear chain reaction associated with conventional methacrylates and results in a volumetric shrinkage of ∼1%. The purpose of this study was to review the literature on a recently introduced resin composite material, Filtek Silorane, and evaluate the clinical outcome of restorations formed in this material.

Methods

Filtek Silorane restorations were placed where indicated in loadbearing situations in the posterior teeth of patients attending five UK dental practices. These were evaluated, after two years, using modified USPHS criteria.

Results

A total of 100 restorations, of mean age 25.7 months, in 64 patients, were examined, comprised of 30 Class I and 70 Class II. All restorations were found to be present and intact, there was no secondary caries. Ninety-seven per cent of the restorations were rated optimal for anatomic form, 84% were rated optimal for marginal integrity, 77% were rated optimal for marginal discoloration, 99% were rated optimal for color match, and 93%% of the restorations were rated optimal for surface quality. No restoration was awarded a “fail” grade. No staining of the restoration surfaces was recorded and no patients complained of post-operative sensitivity.

Significance

It is concluded that, within the limitations of the study, the two year assessment of 100 restorations placed in Filtek Silorane has indicated satisfactory clinical performance.     

Improved bonding of zirconia substructures to resin using a "glaze-on" technique

Objective

To investigate the influence of applying thin intermediary coatings of acid-etchable glasses on the shear bond strength between a methacrylate resin based cement and an yttria-stabilized zirconia dental ceramic substrate.

Methods

The upper and lower surfaces of 110 sintered yttria-stabilised tetragonal zirconia polycrystalline disc-shaped specimens were polished using sequential grades of Silicon Carbide, then air-abraded with 25 μm diameter alumina particles. Specimens were randomly allocated to 11 groups (A–K) (n = 10), group A acting as control. The upper surface of Group A specimens was subjected to a tribochemical coating regime (CoJet, 3M ESPE). Five glazing ceramics were applied and fired according to the manufacturer's recommended firing regime. The glaze was etched with 10% HF acid and all specimens coated with a silane primer. Two differing storage regimes were employed (wet storage vs thermocycling). Shear bond strength testing specimens were created by cementing resin-based composite cylinders to the centre of the prepared ceramic surface using Rely-X Unicem (3M ESPE) resin based cement. Shear bond strength testing was performed and load at failure recorded.

Results

A factorial analysis of variance at a 95% significance level demonstrated that all glazing techniques resulted in a significant increase in the shear bond strength compared with using the resin based cement alone (P < 0.01), with the different glazing ceramics resulting in significant differences in mean shear bond strength (P = 0.008). The differences were a function of the storage state (wet storage vs thermocycling (P = 0.013)).

Conclusion

The glazing techniques used in the current investigation resulted in a significantly enhanced shear bond stress to the resin based cement when compared with the current ‘gold standard’ – tribochemical coating.     

Survival and failure modes: platform‐switching for internal and external hexagon cemented fixed dental prostheses

This study evaluated the probability of survival (reliability) of platform‐switched fixed dental prostheses (FDPs) cemented on different implant–abutment connection designs. Eighty‐four‐three‐unit FDPs (molar pontic) were cemented on abutments connected to two implants of external or internal hexagon connection. Four groups (n = 21 each) were established: external hexagon connection and regular platform (ERC); external hexagon connection and switched platform (ESC); internal hexagon and regular platform (IRC); and internal hexagon and switched platform (ISC). Prostheses were subjected to step‐stress accelerated life testing in water. Weibull curves and probability of survival for a mission of 100,000 cycles at 400 N (two‐sided 90% CI) were calculated. The beta values of 0.22, 0.48, 0.50, and 1.25 for groups ERC, ESC, IRC, and ISC, respectively, indicated a limited role of fatigue in damage accumulation, except for group ISC. Survival decreased for both platform‐switched groups (ESC: 74%, and ISC: 59%) compared with the regular matching platform counterparts (ERC: 95%, and IRC: 98%). Characteristic strength was higher only for ERC compared with ESC, but not different between internal connections. Failures chiefly involved the abutment screw. Platform switching decreased the probability of survival of FDPs on both external and internal connections. The absence in loss of characteristic strength observed in internal hexagon connections favor their use compared with platform‐switched external hexagon connections.     

Clinical performance of extended zirconia frameworks for fixed dental prostheses: two-year results

Summary  The purpose of this prospective cohort study was to assess the performance of tooth-supported, extended zirconia, fixed dental prostheses (FDPs). Thirty FDPs with span-lengths between 36 and 46 mm (mean: 40·33 mm), four to seven units and with connector dimensions of ∼9 mm² were inserted (19 in the posterior region, 11 including anterior teeth) using glass–ionomer cement and assessed (aesthetic evaluation, failures, hypersensitivity/tooth vitality, secondary caries, pocket depth, decementation and chipping) at baseline and after 2 years. Differences between baseline and 2-year recall were analysed using the Wilcoxon signed-rank test for matched pairs. There were five failures. One FDP revealed a core fracture at the base of the connector, probably caused by a damage induced during fabrication. Two FDPs had to be recemented, one abutment tooth had to be treated endodontically and one cohesive failure of the veneer was observed. There were no significant changes of pocket depth and hypersensitivity between baseline and 2-year recall. The aesthetics were rated as excellent by the patients at both baseline and recall. Two year clinical results of extended zirconia based FDPs with 9 mm² connectors are promising.     

Effect of resin matrix composition on the translucency of experimental dental composite resins

ObjectivesThe purpose of this study was to investigate the effect of the resin matrix composition on the translucency of experimental dental composite resins.MethodsThree types of unfilled resin matrices (TEGDMA-, UDMA- and BisGMA-based) were formulated and light cured. In addition, six different experimental dental composite resins with constant filler loading but varying in the type of monomer and the content of BisGMA were fabricated. Discs of each test material with 15.5 mm diameter and 1.0 mm thickness were prepared (N = 3) and light cured. Total and diffuse transmittance values for each sample were measured using a UV/VIS spectrophotometer with the range of readings from 380 to 700 nm. Difference in color was measured using the CIE Lab system.ResultsStatistical analysis by one-way ANOVA followed by Tukey's test showed that there was no statistically significant difference in transmittance values between the three unfilled resins. However, with the addition of filler, BisGMA-containing composite resins showed significantly higher transmittance values than the UDMA- and TEGDMA-based composite resins. Regression analysis revealed that there was a linear correlation between the percentage of BisGMA in the resin matrix and the total and diffuse translucency.SignificanceThe amount of BisGMA used in the resin matrix has a significant effect on the translucency of silica filler-containing dental composite resins.     

上前牙薄弱根管重塑材料与根管内壁黏结界面的显微分析研究

目的:探索Bis-Core复合树脂、水调玻璃离子重塑根管后与根管内壁的黏结界面的显微结构。方法:选择新鲜拔除的人上前牙,根管治疗后去冠,将牙根从中一剖为二,分别用复合树脂、水调玻璃离子对根管壁进行黏结。硬组织切片机制备样本,光学显微镜和原子力显微镜观察根管重塑后材料与牙体界面的微细结构特征。结果:树脂与牙本质的黏结界面上有5μm厚度的玷污层,牙本质小管内的树脂长度约为20μm,而玻璃离子与牙齿界面结合紧密,但无渗透现象。结论:在与根管内壁的黏结方面,Bis-Core树脂优于水调玻璃离子,树脂渗透是其与牙体牢固黏结成整体的重要因素。     

Effect of veneering technique on the fracture resistance of zirconia fixed dental prostheses

Summary To compare the fracture resistance of zirconia 3‐unit posterior fixed dental prostheses (FDPs) frameworks veneered with different veneering materials and techniques before and after artificial ageing. Forty‐eight zirconia 3‐unit FDPs, representing a missing first molar, were adhesively cemented on human teeth. The zirconia frameworks were randomly distributed according to the veneering materials and techniques into three groups, each containing 16 samples: group LV (layering technique/Vintage ZR), group LZ (layering technique/ZIROX) and group PP (CAD/CAM and press‐over techniques/PressXZr). Half of each group was artificially aged through dynamic loading and thermocycling to simulate 5 years of clinical service. Afterwards, all specimens were tested for fracture resistance using compressive load. An analysis of variance (anova ) was used to assess the effect of veneering ceramic and artificial ageing on fracture resistance (P < 0·05). Except for one minor cohesive chipping in group LV1, all specimens survived artificial ageing. The mean fracture resistance values (in Newton) of different non‐aged (± s.d.)/aged (± s.d.) groups were as follows: LV0 2034 (± 401)/LV1 1625 (± 291); LZ0 2373 (± 718)/LZ1 1769 (± 136); and PP0 1959 (± 453)/PP1 1897 (± 329). Artificial ageing significantly reduced the fracture resistance in groups veneered with the layering technique (P < 0·05), whereas no significant effect was found in specimens veneered with the CAD/CAM and press‐over techniques. All tested systems have the potential to withstand occlusal forces applied in the posterior region. The combination of the CAD/CAM and press‐over techniques for the veneering process improved the overall stability after artificial ageing, relative to the layering technique.     

Complication and failure rates of fixed dental prostheses in patients treated for periodontal disease

Objectives: To evaluate the biological and technical complication rates of fixed dental prostheses (FDP) with end abutments or cantilever extensions on teeth (FDP‐tt/cFDP‐tt) on implants (FDP‐ii/cFDP‐ii) and tooth‐implant‐supported (FDP‐ti/cFDP‐ti) in patients treated for chronic periodontitis. Material and methods: From a cohort of 392 patients treated between 1978 and 2002 by graduate students, 199 were re‐examined in 2005. Of these, 84 patients had received ceramo‐metal FDPs (six groups). Results: At the re‐evaluation, the mean age of the patients was 62 years (36.2–83.4). One hundred and seventy‐five FDPs were seated (82 FDP‐tt, 9 FDP‐ii, 20 FDP‐ti, 39 cFDP‐tt, 15 cFDP‐ii, 10 cFDP‐ti). The mean observation time was 11.3 years; 21 FDPs were lost, and 46 technical and 50 biological complications occurred. Chances for the survival of the three groups of FDPs with end abutments were very high (risk for failure 2.8%, 0%, 5.6%). The probability to remain without complications and/or failure was 70.3%, 88.9% and 74.7% in FDPs with end abutments, but 49.8–25% only in FDPs with extensions at 10 years. Conclusions: In patients treated for chronic periodontitis and provided with ceramo‐metal FDPs, high survival rates, especially for FDPs with end abutments, can be expected. The incidence rates of any negative events were increased drastically in the three groups with extension cFDPs (tt, ii, ti). Strategic decisions in the choice of a particular FDP design and the choice of teeth/implants as abutments appear to influence the risks for complications to be expected with fixed reconstruction. If possible, extensions on tooth abutments should be avoided or used only after a cautious clinical evaluation of all options. To cite this article:
Brägger U, Hirt‐Steiner S, Schnell N, Schmidlin K, Salvi GE, Pjetursson B, Matuliene G, Zwahlen M, Lang NP. Complication and failure rates of fixed dental prostheses in patients treated for periodontal disease.
Clin. Oral Impl. Res. 22 , 2011; 70–77.
doi: 10.1111/j.1600‐0501.2010.02095.x     

Clinical performance of long-span zirconia frameworks for fixed dental prostheses: 5-year results

The purpose of this prospective cohort study was to assess the performance of tooth-supported, long-span, zirconia fixed dental prostheses (FDPs). Thirty FDPs with span lengths from 36 to 46 mm (mean 40·33 mm), with 4-7 units and with connector dimensions ～9 mm(2) were inserted (19 in the posterior region, 11 including anterior teeth) using glass-ionomer cement. The performance of the FDPs was assessed (aesthetic evaluation, failures, hypersensitivity/tooth vitality, secondary caries, pocket depth, decementation, and chipping) at baseline and after 5 years. Cox regression analysis was performed to identify risk factors. There were 16 failures after 5 years. Framework fracture occurred for two FDPs, four FDPs had to be re-cemented, one abutment tooth had to be treated endodontically, one abutment tooth fractured and cohesive failure of the veneer occurred for eight. Four FDPs had to be replaced, so survival was 82%. The aesthetics were rated as excellent by the patients at baseline and good at the 5-year recall. Cox regression analysis showed that both length [P = 0·05, exp(B) = 1·22] and location [P = 0·019, exp(B) = 4·09] of the FDP were risk factors for failure. Compared with the previously published 2-year results, the incidence of complications increased dramatically. Additionally, it was shown that long-span FDPs in the molar region are at greater risk of failure than FDPs in the anterior region.     

Assessment of effect of accelerated aging on interim fixed dental materials using digital technologies

PURPOSEThis study assessed the physical and mechanical properties of interim crown materials fabricated using various digital techniques after accelerated aging.MATERIALS AND METHODSThree groups of interim dental restorative materials (N = 20) were tested. The first group (CO) was fabricated using a conventional manual method. The second group (ML) was prepared from prefabricated resin blocks for the milling method and cut into specimen sizes using a cutting disc. The third group (3D) was additively manufactured using a digital light-processing (DLP) 3D printer. Aging acceleration treatments using toothbrushing and thermocycling simulators were applied to half of the specimens corresponding to three years of usage in the oral environment (N = 10). Surface roughness (Ra), Vickers microhardness, 3-point bending, sorption, and solubility tests were performed. A 2-way analysis of variance (ANOVA) and Fisher’s multiple comparison test were used to compare the results among the groups.RESULTSThe mean surface roughness (Ra) of the resin after accelerated aging was significantly higher in the CO and ML groups than that before aging, but not in the 3D group. All groups showed reduced hardness after accelerated aging. The flexural strength values were highest in the 3D group, followed by the ML and CO groups after accelerated aging. Accelerated aging significantly reduced water sorption in the ML group.CONCLUSIONAccording to the tested material and 3D printer type, both 3D-printed and milled interim restoration resins showed higher flexural strength and modulus, and lower surface roughness than those prepared by the conventional method after accelerated aging.     

Influence of the application of a pre-sintered surface augmentation on zirconia and lithium disilicate bonding using an adhesive composite resin cement

ObjectiveThe purpose of this laboratory study is to evaluate the application of a pre-sintered surface augmentation to zirconia (Zir) and lithium disilicate (LDS) ceramics on the delamination strength of adhesive resin cement. The applied surface augmentation was the ruling of lines to the pre-sintered surface of the ceramics.MethodsNinety milled Zir and sixty pressed LDS specimens (3 mm × 0.5 mm × 25 mm) were created and divided into five groups (n = 30). Group 1: Zir no surface treatment (control Zir-NT); Group 2: Zir airborne particle abraded (Zir-APA) with 30 μm CoJet; Group 3: Zir pre-sintered surface augmentation (Zir-SA); Group 4: LDS etched (control LDS-etched) and; Group 5: LDS with pre-sintered surface augmentation and etching (LDS-SA). A resin adhesive cement (3 mm × 1 mm × 8 mm) was then applied and cured to the ceramic specimens. The delamination strength values of the resin cement from the ceramic were recorded. The delamination strength data were analysed statistically using one-way ANOVA and Turkey post hoc analysis.ResultsThe mean delamination strength and standard deviation, when comparing only the Zir-SA to the resin cement were statistically different (p < 0.001); Zir-SA 63.42 ± 11.85, Zir-NT 26.82 ± 12.07, and Zir-APA 48.11 ± 17.85 MPa. Comparison between LDS groups were not significantly different (p = 0.193); LDS-etched 33.49 ± 16.07 and LDS-SA 28.83 ± 10.15 MPa. The delaminated Weibull modulus was highest for surface augmentation Zir specimens (m = 13.56) but decreasing to less than half for Zir-APA (m = 6.27) and Zir-NT (m = 5.68). The Weibull values for the LDS-SA and LDS-etched specimens was 5.63 and 3.38 respectively.SignificanceIncorporating the pre-sintered surface augmentation to zirconia improved the delamination strength and reliability of Zir to the resin cement but not for LDS.     

Survival probability of zirconia‐based fixed dental prostheses up to 5 yr: a systematic review of the literature

Schley J‐S, Heussen N, Reich S, Fischer J, Haselhuhn K, Wolfart S. Survival probability of zirconia‐based fixed dental prostheses up to 5 yr: a systematic review of the literature.
Eur J Oral Sci 2010; 118: 443–450. © 2010 Eur J Oral Sci The purpose of this systematic review was to calculate the 5‐yr survival rates of all‐ceramic zirconia‐based fixed dental prostheses (FDPs) and to analyze technical and biological complications. An electronic literature search of MEDLINE (PubMed) was conducted independently by three reviewers to identify clinical studies from 1999 to 2009 and was completed by a manual search. Keywords and inclusion and exclusion criteria were well‐defined. The search revealed 399 titles and led to the final analysis of 18 full‐text articles. Nine studies met the inclusion criteria. Extracted data were statistically calculated into 5‐yr survival rates and 5‐yr complication‐free rates by using Poisson regression analysis. In total, 310, 3‐ to 4‐unit FDPs and 20 FDPs with more than 4 units were included. The estimated 5‐yr survival rate for all FDPs was 94.29% (95% CI: 58.98–99.32); 19 FDPs were lost as a result of catastrophic failures. The 5‐yr complication‐free rate regarding technical complications was 76.41% (95% CI: 42.42–91.60) with chipping being the most frequent complication. Regarding biological complications, the 5‐yr complication‐free rate was 91.72% (95% CI: 59.19–98.53). The survival rates of zirconia‐based short‐unit FDPs are promising. However, an important improvement of the veneering systems is required, and for FDPs with more units in function, further randomized, controlled clinical trials are necessary.     

Fracture strength of temporary fixed partial dentures: CAD/CAM versus directly fabricated restorations

Objectives

This study aimed at investigating the influence of fabrication method, storage condition and material on the fracture strength of temporary 3-unit fixed partial dentures (FPDs).

Methods

A CrCo-alloy master model with a 3-unit FPD (abutment teeth 25 and 27) was manufactured. The master model was scanned and the data set transferred to a CAD/CAM unit (Cercon Brain Expert, Degudent, Hanau, Germany). Temporary 3-unit bridges were produced either by milling from pre-fabricated blanks (Trim, Luxatemp AM Plus, Cercon Base PMMA) or by direct fabrication (Trim, Luxatemp AM Plus). 10 FPDs per experimental group were subjected either to water storage at 37 °C for 24 h and 3 months, respectively, or thermocycled (TC, 5000×, 5-55 °C, 1 week). Maximum force at fracture (Fmax) was determined in a 3-point bending test at 200 mm/min. Data was analyzed using parametric statistics (α = 5%).

Results

Fmax values ranged from 138.5 to 1115.5 N. FPDs, which were CAD/CAM fabricated, showed a significant higher Fmax compared to the directly fabricated bridges (p < 0.05). TC significantly affected Fmax for Luxatemp (p < 0.05) but not for the PMMA based materials (p > 0.05). CAD/CAM milled FPDs made of Luxatemp showed significantly higher Fmax values compared to Trim and Cercon Base PMMA (p < 0.05).

Significance

CAD/CAM fabricated FPDs exhibit a higher mechanical strength compared to directly fabricated FPDs, when manufactured of the same material. Composite based materials seem to offer clear advantages versus PMMA based materials and should, therefore, be considered for CAD/CAM fabricated temporary restorations.     

Repair bond strength of resin composite to restorative materials after short- and long-term storage

ObjectivesTo investigate short- and long-term bond strength (“repair bond strength”; RBS) of a resin composite to six restorative materials using either a silane and a bonding agent or a universal “one-step self-etch” adhesive system.MethodsSpecimens were produced from an amalgam, a direct resin composite, two indirect resin composites, a hybrid ceramic, and a feldspar ceramic and stored for 3 months in tap water (37 °C). All specimens were then sandblasted (Al₂O₃; 25 μm) and either treated with Monobond Plus and OptiBond FL Adhesive (MP-OFL) or with Scotchbond Universal (SBU). Filtek Z250 was used as “repair composite”, and RBS was measured by means of a micro shear bond strength test after 24 h or after 1 year. RBS values (n = 15/group) were statistically analyzed (α = 0.05).ResultsRBS (MPa; mean values (standard deviations)) after 24 h for MP-OFL: 18.6 (3.2)–23.9 (5.0) and for SBU: 12.5 (4.9)–18.1 (4.6); after 1 year for MP-OFL: 8.9 (4.6)–19.8 (4.3) and for SBU: 5.6 (2.3)–18.8 (3.5). After 24 h, MP-OFL showed significantly higher RBS to the hybrid ceramic and the feldspar ceramic than did SBU (p ≤ 0.0001) whereas there was no significant difference in RBS for the other four restorative materials. After 1 year, MP-OFL showed significantly higher RBS to the feldspar ceramic than did SBU (p = 0.043) whereas there was no significant difference in RBS for the other five restorative materials.SignificanceThe use of a silane and a bonding agent seems more versatile for repairing restorations than the use of a universal “one-step self-etch” adhesive system.     

Effect of surface treatments on the tensile bond strength of repaired water-aged anterior restorative micro-fine hybrid resin composite

OBJECTIVES: The purpose of this study was to characterize changes in surface topography associated with different surface treatments and their effect on tensile bond strength (TBS) of repaired water-aged anterior restorative micro-fine hybrid resin composite. METHODS: The TBS of repaired resin-based composite slabs either non-treated or exposed to different mechanical and/or chemical surface treatment procedures were measured. The cohesive tensile strength of non-repaired intact slabs was used as a control group. The topographical effects of acid etching, grinding, and grinding followed by acid etching were characterized by AFM and SEM. RESULTS: All repaired groups showed significantly lower TBS than the control group. The TBS of repaired groups was ranged from 15% to 59% of the cohesive tensile strength of the control group (18.8+/-4.5MPa). The surface roughness of the non-treated aged specimens was significantly higher than other treated specimens. Specimens treated by acid etching showed significant increase in surface area compared to the non-treated and treated specimens. CONCLUSIONS: Aging process resulted in the formation of degradable surface layer which adversely affects the repair bond strength. The use of silane primer prior to the application of the adhesive after mechanical grinding, with or without the use of 37% phosphoric acid etching; improves the repair bond strength.