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PubMed2005

A rough surface finish adversely affects the survivorship of a cemented femoral stem.

UNLABELLED: To assess the role of surface finish in the survivorship of a cemented femoral stem, we evaluated the midterm clinical and radiographic performances of a cohort of patients who had total hip arthroplasties with two cemented femoral stems that differed only in surface finish. One hundred seventy-five patients [64 total hip arthroplasties with rough, textured stems (radius, 1.75-2.5 microm) and 138 total hip arthroplasties with satin finish, textured stems (radius, 0.5 microm)] were followed up clinically and radiographically for 4-8 years. All surgeries were done by one surgeon using the same surgical technique, acetabular cup, cement type, and cementing technique. The groups had similar demographics, diagnoses, preoperative clinical scores, cement mantle qualities, alignments, and lengths of followup. Seven hips in the rough surface group and none in the satin surface group had aseptic loosening. The femoral bone-cement interface showed progressive radiolucent lines or osteolysis in eight of 64 rough stems and in three of 138 satin stems. A rough, textured stem of this design is more likely to fail at intermediate followup than a satin surface stem. We recommend that the surface of cemented stems should be satin or polished with a radius less than 0.5 microm. LEVEL OF EVIDENCE: Therapeutic study, Level III-1 (case-control study). See the Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMed1978

The influence of surface roughness on the retentive ability of two dental luting cements.

Two series of brass cones and two series of dentine posts with varying surface roughness were produced. Maximum roughness value and arithmetical mean roughness were recorded for each cone. Brass crowns were cemented either with zinc phosphate cement (De Trey's zinc Cenment Improved) or with polycarboxylate cement (Durelon). A tensile stress was applied until the crown and the cone separated. The retentive force in relation to retention area was measured. The results showed that the retentive ability of both cements increased with increasing surface roughness. The increase in retention was greater for brass than for dentine. Differences were also found between the two cements; on smooth surfaces the zinc phosphate cement had a lower retentive ability than the polycarboxylate cement, but on rough surfaces the opposite relationship was observed.

Acrylic Resins↗
PubMed1994

Effect of restoration composition, shade, and thickness on the cure of a photoactivated resin cement.

PURPOSE: This study investigates the effect of selected properties of a restorative material (type, shade, and thickness) on the cure of a photoactivated resin cement. MATERIALS AND METHODS: Disks of ceramic and resin-based restorative materials of two extreme shades were made to provide thicknesses of 0.5 to 3.0 mm in 0.5-mm intervals. Light transmission was measured through various thicknesses and shades of each restorative material type. The effect of light transmission, as influenced by restorative material type, shade, and thickness on resin cement cure was also determined. RESULTS: Thickness and shade of restorative material had the greatest influence on light transmission. For simulated restoration thicknesses 1.5 mm and greater, Dicor (Dentsply International Inc, York, PA) had greater transmission of light than the other materials, regardless of shade. At equal restorative material thickness, light transmission was similar for identical shades of the other three materials. Restoration shade and thickness also had the greatest influence on resin cement cure. Material type, although significant, had only a minor influence. At thicknesses of 1 to 2 mm, Dicor consistently yielded greater resin cement cure values than any other material tested. CONCLUSIONS: When considering the ability of restorative materials to transmit light for curing of photo-activated resin cements, the thickness of the restoration and its shade are much more influential than the choice of restorative material. Dicor provides greater light transmission that results in the ability to photobond restorations of greater thicknesses than the other materials. For restorations greater than 1 mm in thickness, a dual cure or chemical cure resin cement should be used to provide maximal cement properties.

Analysis of Variance↗
PubMedDate not supplied

The effect of fatigue damage on the force required to remove a restoration in a cement-retained implant system.

PURPOSE: To evaluate the luting agents and retentive forces before and after mechanical stressing. MATERIALS AND METHODS: Sample size N was 12 for each group, and 12 Cera-One closed-end gold cylinders were cemented with three types of luting cements (ImProv, UltraTemp, and TempBond). The force required to remove the gold cylinders from the abutments was determined with an MTS testing machine. After cleaning and recementing the cylinders, the samples were placed in the housings of an Alabama-type three-body wear machine and load of 110 N was applied to the gold cylinders at a frequency of 80 cycles/min for 50,000 cycles. Then each cylinder was pulled from its abutment and the force at which the failure occurred was recorded. The procedure was repeated with 300,000 cycles. RESULTS: Statistical analysis arising from two-way ANOVA found that the forces required to remove the abutments were significantly different. The most retentive cement was ImProv. Before cyclic loading, on average, ImProv produced a retentive value 85% higher than that yielded by TempBond, and 25% higher than that of UltraTemp. The three cements were significantly different at each of the three cycle levels. CONCLUSIONS: These results might suggest TempBond luting agent as the material of choice for provisional cementation because it allows easier removal of the prosthesis and maintains enough retention to prevent loosening of the restoration. The clinical implication is that the effect of cyclic load on the strength of the cements is different, an important factor in selection of a cement. ImProv had the highest retentive value before and after the two cycles, and TempBond had the lowest. UltraTemp had the highest percentage of retentive value lost. TempBond had no significant loss under loading even though initially it was the weakest.

Acrylic Resins↗
PubMed2000

In vitro investigation of aluminum and fluoride release from compomers, conventional and resin-modified glass-ionomer cements: a standardized approach.

The amount of fluoride release from dental cements necessary for an anticariogenic effect is not established: moreover, the possible toxic effects due to high fluoride and aluminum release are not well known and the results are still controversial. The aim of our study was to evaluate fluoride (F) and aluminum (Al) release from dental cements using a 'standardized approach' according to the end-use of the materials, i.e. biocompatibility testing. Two polyacid-modified resin composites of recent application, commonly called compomers (Dyract and Dyract Cem), were compared with two conventional acid-based (Fuji I, Ketac-Cem) and two resin-modified (Vitremer, Vitrebond) glass-ionomer cements (GICs). All types of cement are used in dentistry and are commercially available. Extracts of the cements into minimum essential medium, after setting over a 1-h (group A) and 1-week (group B) period, were performed. The extraction conditions were rigorously standardized. Mean values +/- standard deviation of F- and Al-levels in such extracts were measured and were expressed as microg g(-1) (micrograms of ions per gram of cement). A great difference in the amount of ion release, both F and Al, was shown among the tested materials. The GICs, as well as Ketac-Cem, released more F and Al than the compomers. All of the materials released the greatest proportion of ions when the extraction was performed in the first hour after mixing (group A). Al- and F-values showed a highly significant positive correlation, independently from the curing time. We conclude that the biological assessment of dental cements can be performed only if a pre-evaluation of the leachables is obtained by applying a standardized protocol which allows a useful comparison between the different materials.

Aluminum↗
PubMed1997

Setting reaction and hardening of an apatitic calcium phosphate cement.

The combination of self-setting and biocompatibility makes calcium phosphate cements potentially useful materials for a variety of dental applications. The objective of this study was to investigate the setting and hardening mechanisms of a cement-type reaction leading to the formation of calcium-deficient hydroxyapatite at low temperature. Reactants used were alpha-tricalcium phosphate containing 17 wt% beta-tricalcium phosphate, and 2 wt% of precipitated hydroxyapatite as solid phase and an aqueous solution 2.5 wt% of disodium hydrogen phosphate as liquid phase. The transformation of the mixture was stopped at selected times by a freeze-drying techniques, so that the cement properties at various stages could be studied by means of x-ray diffraction, infrared spectroscopy, and scanning electron microscopy. Also, the compressive strength of the cement was measured as a function of time. The results showed that: (1) the cement setting was the result of the alpha-tricalcium phosphate hydrolysis, giving as a product calcium-deficient hydroxyapatite, while beta-tricalcium phosphate did not participate in the reaction; (2) the extent of conversion of alpha-TCP was nearly 80% after 24 hr; (3) both the extent of conversion and the compressive strength increased initially linearly with time, subsequently reaching a saturation level, with a strong correlation observed between them, indicating that the microstructural changes taking place as the setting reaction proceeded were responsible for the mechanical behavior of the cement; and (4) the microstructure of the set cement consisted of clusters of big plates with radial or parallel orientations in a matrix of small plate-like crystals.

Bone Cements↗
PubMed2004

Pre-heating of components in cemented total hip arthroplasty.

Fatigue fractures which originate at stress-concentrating voids located at the implant-cement interface are a potential cause of septic loosening of cemented femoral components. Heating of the component to 44 degrees C is known to reduce the porosity of the cement-prosthesis interface. The temperature of the cement-bone interface was recorded intra-operatively as 32.3 degrees C. A simulated femoral model was devised to study the effect of heating of the component on the implant-cement interface. Heating of the implant and vacuum mixing have a synergistic effect on the porosity of the implant-cement interface, and heating also reverses the gradients of microhardness in the mantle. Heating of the implant also reduces porosity at the interface depending on the temperature. A minimum difference in temperature between the implant and the bone of 3 degrees C was required to produce this effect. The optimal difference was 7 degrees C, representing a balance between maximal reduction of porosity and an increased risk of thermal injury. Using contemporary cementing techniques, heating the implant to 40 degrees C is recommended to produce an optimum effect.

Arthroplasty, Replacement, Hip↗
PubMed2002

Cemented femoral revision: technique and outcome.

Long-term pain relief and improved function in patients with failed or infected hip replacement, or, occasionally for patients with impending surgical failure, are the goals of total hip revision arthroplasty. Cement techniques for femoral and reconstructions in patients needing total hip revision are discussed in this article. Advantages of cemented technique include the ability to incorporate antibiotics into the cement during reimplantation following periprosthetic infection. Cemented technique is also preferable over cementless techniques when there is extensive diaphyseal bone loss, which precludes predictable biologic fixation. Cement-within-cement technique is indicated for well-fixed cemented femoral components that require revision for instability, improved acetabular exposure, equalization of leg lengths, or damage to a monoblock femoral head.

Bone Cements↗
PubMed2001

[Bonding and mechanical interlocking of three kinds of luting cements in retention of complete metal crowns].

OBJECTIVE: To evaluate the effects of bonding and mechanical interlocking of three kinds of luting cements in the retention of complete metal crowns. METHODS: Zinc phosphate cement (ZP), glass ionomer cement (GI) and polycarboxylate cement (PC) are in common use for clinical treatment. In this study, these cements were selected to bond the complete crowns to molars in vitro. The retention capacities of the complete crowns were tested and compared. And apart from mechanical interlocking, the effect of bonding was tested. On this basis the interlocking capacity of the cement was calculated. RESULTS: 1. The retention capacities of complete metal crowns from the highest to least were: GI > ZP > PC. 2. The proportions of mechanical interlocking of ZP, GI and PC in the retention of complete metal crowns were 62.6%, 48.3% and 20.1% and the ratios of bonding of ZP, GI and PC were 37.4%, 51.7% and 79.9%, respectively. CONCLUSION: The effects varied with different cements in the retention of complete metal crowns because of the discrepancy in bonding and mechanical interlocking properties. Mechanical interlocking plays a prominent role when ZP or GI is used, and the role of bonding is apparent in PC.

Adhesives↗
PubMed2002

Effects of different types of temporary cements on the tensile strength and marginal adaptation of crowns on implants.

PURPOSE: The aim of this study was to evaluate the influence of four different types of temporary cements, Tempbond (Kerr), Tempbond NE (Kerr), Improv (Sterioss), and Dycal (Dentsply/Caulk), on the marginal adaptation and tensile strength of prosthetic specimens cemented on replicas of CeraOne abutments. MATERIALS AND METHODS: Four test groups were formed: Group 1 (G-1), Tempbond (Kerr); Group 2 (G-2), Tempbond NE (Kerr); Group 3 (G-3), Improv (Sterioss); Group 4 (G-4), Dycal (Dentsply/Caulk). For the specimens, gold cylinders (DCB 160, Nobel Biocare) adapted to stainless steel replicas of CeraOne abutments (Nobel Biocare) were utilized. The replicas on a stainless steel base were made in a special machine for implant components. The cement thicknesses for each luting agent were measured using a Measurement Comparative Microscope (Mitutoyo). The readings obtained before cementation were used as the controls (G-0). Following each group's cementation, the specimens were submitted to tensile strength tests with a Universal Testing Machine (Kratus). RESULTS: The results of the marginal adaptation test as reflected by cement thicknesses were: G-0 = 11.7 microm, G-1 = 35.7 microm (+/- 8.8), G-2 = 41.7 microm (+/- 9.0), G-3 = 32.6 microm (+/- 9.7) and G-4 = 38.2 microm (+/- 6.7). The tensile strength tests yielded the following values: G-1 = 58.5 N (+/- 14.8), G-2 = 51 N (+/- 8.2), G-3 = 61.8 N (+/- 17.1) and G-4 = 71.8 N (+/- 9.3). CONCLUSION: The four temporary cements tested all provided similar marginal adaptation. G-4 (Dycal) showed a higher tensile strength than G-2 (Tempbond NE).

Analysis of Variance↗
PubMed1992

The fit of all-ceramic crowns cemented with different luting agents.

In this article the fit of all-ceramic crowns, cemented with different luting agents (zinc phosphate and resin cements), was investigated using a scanning electron microscope. The marginal opening of all-ceramic crowns cemented with zinc phosphate cement was 111.9 +/- 40.6 microns which was significantly greater than the 46.7 +/- 12.9 microns marginal opening of Cerestore crowns cemented with resin cement. Total film thicknesses of the cements were not uniform and there were certain discrepancies from margins to walls and to tip due to the die spacer.

Aluminum Oxide↗
PubMedDate not supplied

Increased antibacterial activity of zinc polycarboxylate cement by the addition of chlorhexidine gluconate in fixed prosthodontics.

PURPOSE: This study evaluated the antibacterial activity of water-activated zinc polycarboxylate cement with adjunctive 0.12% chlorhexidine gluconate on the subgingival microbiota in fixed partial dentures. MATERIALS AND METHODS: Thirty-six teeth prepared as fixed partial denture abutments in 9 patients were cemented randomly using water-activated zinc polycarboxylate cement (control group) or water-activated zinc polycarboxylate cement, including 0.12% chlorhexidine gluconate (test group). A total of 108 subgingival plaque samples were analyzed at baseline, immediately before permanent cementation (5 weeks), and 8 weeks later (at 13 weeks). RESULTS: In the control group, the subgingival microbiota altered to closely resemble the flora of chronic gingivitis (increased proportions of gram-negative anaerobes such as Prevotella intermedia, Fusobacterium nucleatum) by 13 weeks. In contrast, the microflora at test sites comprised predominantly gram-positive facultative cocci and rods at 13 weeks. CONCLUSION: This study demonstrated that the addition of 0.12% chlorhexidine gluconate may enhance the antimicrobial action of polycarboxylate cements to ensure the maintenance of a microflora compatible with periodontal health, at least up to 13 weeks post-cementation.

Adult↗
PubMed2005

Bonding of resin cements to post materials: influence of surface energy characteristics.

PURPOSE: 1) To determine the surface energy characteristics of three variously treated post materials and two resin cements, and 2) to investigate if previously measured bond strengths between cements and treated posts could be related to the surface energy characteristics of the posts and cements. MATERIALS AND METHODS: The post materials were those of ParaPost XH, ParaPost Fiber White, and Cerapost, and the resin cements were ParaPost Cement and Panavia F. The post materials were surface treated by grinding, sandblasting, CoJet, or with Alloy Primer. Droplets of four reference liquids were placed on the surfaces and the contact angles measured. On this basis the dispersive, acid, and base components of the surface free energy of the materials were calculated. Then the thermodynamic work of adhesion between resin cements and treated post surfaces was calculated, as well as its dispersive and polar components. RESULTS: It was found that the surface energy characteristics varied significantly between the investigated surfaces. The previously measured bond strengths correlated statistically significantly (p < 0.02) to the dispersive component of the work of adhesion between posts and cements (r = 0.53), to the dispersive component of the surface free energy of the posts (r = 0.54), and to the contact angle determined with ethylene glycol as reference liquid (r = -0.52), but not to other surface energy characteristics. CONCLUSION: In spite of the significant correlations, the "explained" part of the variation in bond strength did not surpass 30%. This means that factors other than surface energy characteristics of adherend and adhesive play a role in determining the strength of the bond.

Dental Cements↗
PubMedDate not supplied

The effect of various surface coatings on fluoride release from glass-ionomer cement.

To protect glass-ionomer cement from moisture contamination and dehydration during initial setting, immediate application of a surface coating agent is recommended. This study compared the effect of various surface coatings on F release from glass-ionomer cement. Twenty glass-ionomer cement (Ketac Fil Aplicap) disks (4.52 cm2) were prepared from a Teflon mold. The control group was uncoated, while the experimental groups were coated with Visiobond, Scotchbond II, and Ketac Varnish. In addition, five specimens of Variglass were similarly prepared and remained uncoated as per the manufacturer's instructions. F release was measured each day during week 1 and on the last day of weeks 2, 3, and 4. The results indicated that the application of the surface coatings did not completely inhibit F release from glass-ionomer cements, and that F release during the first week for all groups was significantly greater than in the subsequent 3 weeks. Visiobond-coated glass-ionomer cement allowed significantly more F release than Scotchbond II-coated glass-ionomer cement, Ketac Varnish-coated glass-ionomer cement, or Variglass.

Acrylic Resins↗
PubMed1996

An in vitro comparison of micro leakage in three glass ionomer cements used as retrograde filling materials.

The aim of this study was to evaluate the sealing ability of conventional self-cured glass ionomer cement, silver glass ionomer cement and light-cured glass ionomer cement as retrofilling materials. Micro-leakage was assessed by introducing the samples into a 1 per cent solution of methylene blue for eight days at a constant temperature of 37 degrees C. Dye penetration was greater when silver glass ionomer cement was used in comparison to the other two materials tested; the difference was statistically significant. Conversely, the sealing ability of light-cured glass ionomer cement was significantly higher than that of conventional glass ionomer cement. The condition of the dentine-filling material interface and the marginal adaptation of the glass ionomer cements under study were assessed using scanning electron microscopy.

Cermet Cements↗
PubMedDate not supplied

Interaction of bone and hydroxyapatite filled 4-META/MMA-TBB bone cement in in vitro and in vivo environments.

Bone response to hydroxyapatite (A) fillers in the cured 4-methacryloyloxyethyl trimellitate anhydride (4-META)/metyl methacrylate (MMA) - tri-n-butyl borane (TBB) adhesive bone cement was evaluated. Two component system consisting of powder and liquid was formulated. The liquid portion was 5% 4-META in MMA and TBB; Powder was composed of 50 wt% poly(MM/a) (PMMA) and 50 wt% dense HA particles. The results indicated that the tensile strength decreased when the HA filler size increased. Thirty-six implants in three dogs for up to 12 weeks showed HA filled PMMA-4 META cement was stable in the cement-bone interface. Histologic examinations showed that the exposed HA particles at the surface of the cured cement were generally associated with bone formation without fibrous tissue, as well as interdigitation of cement to bone. Suggesting the importance of HA fillers in inducing bone apposition that results in stable cement binding to bone, thereby complementing fast initial bone fixation of the cement.

Animals↗
PubMed1989

Load transfer of posts and cores to roots through cements.

This study evaluated differences in load transfer when cast posts are fixed to roots with different cements. Cast posts and cores were cemented with 40 endodontically prepared teeth by using four different cement mediums. The load exerted on the root surface through the post was evaluated using a strain gauge. The increased flexure after cementation was statistically analyzed. In conclusion, there was load transfer from post to root structure when posts were cemented, but no difference was found between cementation mediums.

Cementation↗
PubMed1992

Radiographic appearance of titanium alloy prefabricated posts cemented with different luting materials.

Eight luting materials were compared to determine which of them obscured the radiographic image of a cemented titanium alloy prefabricated post. Eight extracted, endodontically treated, maxillary molar teeth were selected for the study. A post channel was prepared in the lingual root canal of each tooth and a titanium alloy prefabricated post was cemented with one of the selected luting materials. Preoperative, precementation, and postcementation radiographs were compared visually to determine the outline of the cemented titanium alloy post. Glass ionomer cements obscured the outline more than composite resin cements but less than zinc phosphate or polycarboxylate cements. Further study is indicated before recommendation of a luting material with titanium alloy prefabricated posts.

Alloys↗