Shear bond strength of orthodontic brackets cemented with a zinc oxide-polyvinyl cement

The purpose of this study was to compare the shear bond strengths and enamel surface structure after debonding a conventional metal bracket and a polycrystalline ceramic bracket bonded with a bipolar zinc oxide-polyvinyl cement (F-21) or a light-cured resin cement (Transbond). Forty extracted human premolars were used. The buccal enamel surfaces were used, and the teeth randomly divided into four groups of 10 teeth each: group 1: conventional metal bracket (Unitek) bonded with Transbond; group 2: metal bracket bonded with F-21; group 3: ceramic bracket (Transcend 2000) bonded with Transbond; and group 4: ceramic bracket bonded with F-21. The brackets were bonded to the etched enamel surfaces according to manufacturer's instructions. All specimens were stored in distilled water for 24 hours and then thermocycled for 300 cycles between 5 degrees C and 55 degrees C. The specimens were mounted in dental stone and placed in the Instron at a crosshead speed of 0.5 mm/min with a knife-edged blade. Immediately after debonding, the enamel surface and bracket-enamel interface were evaluated visually and with a stereomicroscope. Representative samples were then examined with the scanning electron microscope. The analysis of variance and Student-Newman-Keuls tests were performed. The results in megapascals were Group 1: 19,6 (+/- 9,6); group 2: 14,3 (+/- 4,6); group 3: 28,8 (+/- 12,6); and group 4: 18,5 (+/- 7,5). Group 3 was statistically significantly different (P < 0.008) from all other groups. Groups 1, 2, and 4 were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)     

Demineralization effects of 10 percent carbamide peroxide

OBJECTIVES: The purpose of this in vitro study was to measure the amount of calcium lost from enamel exposed to a 10% carbamide peroxide solution. METHODS: Nine teeth (3 incisors, 2 premolars, 4 molars) were sectioned to serve as paired test and control specimens. Each tooth half was coated with wax, leaving a uniform 3 mm x 4 mm window of exposed enamel. Test specimens were placed in culture tubes with 1.00 ml of deionized water and 0.02 ml of 10% carbamide peroxide for 6 h; controls were exposed to water alone. Calcium concentrations in the solutions were measured using a Perkin-Elmer 5100 atomic absorption spectrophotometer. RESULTS: Teeth exposed to carbamide peroxide lost an average of 1.06 micrograms/mm2 of calcium. This amount of loss was significantly greater than controls (p < 0.001), according to ANOVA. For comparison, teeth were exposed to a cola beverage for 2.5 min, the time equivalent of drinking a 16 oz. beverage. The amount of calcium lost from these teeth was also about 1 microgram/mm2. CONCLUSIONS: Teeth exposed to 10% carbamide peroxide lost calcium. However, the amount of loss was small, and may not be clinically significant.     

Wear resistance of four luting agents as a function of marginal gap distance, cement type, and restorative material

This study investigated the effect of marginal gap width, luting cement, and restorative material on the wear resistance of the luting cement in areas where no occlusal contact is present. Three types of resin luting cement and one resin-modified glass-ionomer cement were used with two inlay systems, a resin composite, and an all-ceramic system. Bovine enamel represented tooth structure. Toothbrush abrasion was the wear modality. Three predetermined gap widths were selected: 240 +/- 30 microns, 150 +/- 30 microns, and 60 +/- 30 microns. All specimens were thermocycled. Regardless of the luting cement or the restorative material, there was a significant difference (P < 0.05) in wear resistance of the cement among the three gap distances at both the enamel and restoration interface. Vertical wear of the luting cement at the enamel interface increased linearly with marginal gap distance when all four cements were considered together (r2 > 0.51), regardless of type of restorative material used. The resin-modified glass-ionomer cement showed the least amount of wear for all variables considered. Significant differences in wear were found between the four luting cements at wide gap distances (240 microns) at the enamel interface, regardless of type of restorative material used. No significant differences were found between the two restorative materials at the enamel interface at the three gap distances.     

Effects of different surface treatment methods on the bond strength of composite resin to porcelain

In this study failures of composite resin/ porcelain interfaces under shear loading were examined. Porcelain firing were made onto metal cylinders and porcelain surfaces were roughened with burrs or treated with hydrofloric acid gel and/ or sandblasted with a Microetcher. Two silane coupling agents were used in five groups, each of which had 22 samples. All of the treated samples were restored with a hybrid-type composite resin. Then each group was divided into two subgroups according to storage times of 24 h and 30 days. After thermocyling the samples which were stored for 30 days, all of the groups were subjected to shear force at the composite resin/porcelain interface until fracture occurred. The results showed that there were differences both in the 24-h and 30-day storage period bond strengths between the various surface treatment methods. The samples treated with all three of the Microetcher, hydrofloric acid and silane exhibited the highest shear bond values after 24 h storage, followed by the microetched/silane and the hydrofluoric acid/silane groups (F: 570.31, P: 0.00). After 30 days, the highest mean shear bond strength values were again with samples treated by all three processes. The storage period and thermocycling decreased the bond strength of samples, however, there was a significant difference among groups (F: 1388-55, P: 0.00). Silane pre-treatment of porcelain was important as the mean bond strength of sandblasted/etched specimens were significantly lower than the other groups which were treated mechanically, in 24 h. Sandblasting seems to have little effect on the bonding. The comparison of 24-h and 30-day samples have also significant difference (F: 91.4376, P: 0.00).     

Enamel and dentine shear bond strength of two resin modified glass ionomers and two resin based adhesives

OBJECTIVES: The purpose of this in vitro study was to compare the shear bond strength to enamel and dentine of two resin modified glass ionomers (Fuji Bond L.C. and Vitrebond) and two resin based adhesives (Prime&Bond 2.1 and Scotchbond Multi-Purpose). METHODS: A total of 120 bond sites were prepared on either enamel (n = 60) or dentine (n = 60) on human molars by grinding the teeth flat with a 600 grit sandpaper. Each tooth substrate group was divided into four groups (n = 15) to match each material. Each of the four material systems was applied, according to the manufacturers instructions, to the bond sites. On top of the placed material, a microfilled composite was placed in a 2.5 mm diameter matrix and light-cured for 40 s. All specimens were thermocycled 500 times (5-55 degrees C). Shear bond strength values were determined 120 h after bonding using a Zwick testing machine. One-way ANOVA was used to determine whether significant differences (p < 0.05) existed among the material groups on enamel and dentine. Pairwise comparisons were used to determine significant differences (p < 0.05) among the four products. RESULTS: The ANOVA revealed strong significant differences on enamel (p = 0.0001) and dentine (p = 0.0172). The enamel bond strength values of the two resin based adhesives were significantly higher than one of the resin modified glass ionomers (Vitrebond), while the other resin modified glass ionomers did not differ from Scotchbond Multi-Purpose. On dentine, however, Vitrebond performed significantly better than the two resin based adhesives. CONCLUSIONS: The investigated resin modified glass ionomers bonded better to dentine surfaces than to enamel surfaces, while the investigated resin based adhesive systems bonded better to enamel than to dentine.     

Surface cracking identified in polished and self-glazed dental porcelain

PURPOSE: Polishing and glazing porcelain surfaces of restorations is thought to help reduce the wear on the opposing occlusion because of reduced roughness. MATERIALS AND METHODS: To test this theory, samples of a variety of dental porcelains were prepared and subjected to various polishing and self-glazing treatments commonly used in dentistry and then viewed using scanning electron microscope (SEM). Fine cracks were discovered in the surface of the samples that had been polished and then self-glazed. These cracks were typically greater than 50 microns in length with submicron surface openings and crack depths less than 20 microns. To establish the treatments responsible for the formation of these cracks, a more controlled study was performed. Samples of Vita VMK 68 no. 559 incisal porcelain (Vita Zahnfabrik, Bad S?chingen, Germany) were prepared and subjected to six treatments (sample size = 3): treatment no. 1, as-fired condition; treatment no. 2, self-glazed (32 degrees C per minute to 960 degrees C, then cooled); treatments no. 3 and 4, wet ground followed by 1 micron diamond polish (no. 4 was then self-glazed); treatments no. 5 and 6, ground and polished using a Shofu porcelain adjustment kit (Shofu Inc, Kyoto, Japan) (no. 6 was then self-glazed). The samples were observed using SEM. RESULTS: Treatments no. 1, 2, 3, and 5 showed no cracking; however, treatments no. 4 and 6 showed cracking in all specimens (approximate levels 5,100 microns/mm2 and 3,600 microns/mm2, respectively). CONCLUSIONS: Polishing followed by self-glazing produces fine surface cracks. The rougher surface resulting from the surface cracks and subsequent porcelain chipping may cause wear of opposing occlusal surfaces.     

The effect of dentin primer on the tensile bond strength to human enamel

Four third-generation dentin bonding products (Scotchbond Multi-Purpose, Optibond, All-Bond 2, and Prisma Universal Bond 3) were tested to evaluate their tensile bond strength to enamel. Test enamel specimens were etched, primed, and polymerized according to each manufacturer's directions. Control specimens were treated identically except the primer application was eliminated. The results demonstrated that the dentin primer significantly increased the tensile bond strength of All-Bond 2, significantly decreased the tensile bond strength of Scotchbond Multi-Purpose and Optibond, and had no significant effect for Prisma Universal Bond 3. A one-way analysis of variance was run between the eight groups tested, and three significant subsets were found (P < .05). The subset with the highest mean tensile bond strengths consisted of Prisma Universal Bond 3 primed and nonprimed, All-Bond 2 primed, and Optibond nonprimed.     

Surface layer characterization after dual ion exchange of a leucite-reinforced dental porcelain

The dual ion-exchange technique has been shown to improve the strength of feldspathic dental porcelains by first replacing constituent alkali ions with smaller ions above the strain point, and then exchanging the smaller ions for larger ions at temperatures below the strain point. The strength increase is directly related to the thickness of the surface-exchanged layer. This study evaluated the thickness of the exchanged layer after dual ion exchange of a leucite-reinforced dental porcelain. Optec HSP porcelain disks were fabricated, submitted to a dual ion-exchange treatment, and indented at various loads before determining the biaxial flexure strength. The mean flexural strength for the ion-exchanged groups was significantly higher than for control groups, except when the depth of the median crack exceeded 138 microns. Wavelength Dispersive Spectrometry analyses on cross sections showed that the mean potassium amount in the glassy matrix was significantly lower (P < .001) for the treated specimens than for the controls. The mean thickness of the exchanged layer after dual ion exchange was estimated at 140 microns.     

Effect of etchant, etching period, and silane priming on bond strength to porcelain of composite resin

The purpose of this study was to evaluate the effect of etching and silane priming on bond strength to a feldspathic porcelain (VMK 68) of a composite resin (Clearfil APX). Two hydrofluoric acid etchants (2.5% and 5%) and seven different etching times (0, 30, 60, 90, 120, 150, and 180 seconds) were used to etch the porcelain specimens respectively. A self-curing bonding agent containing a silane coupler (Clearfil Porcelain Bond) was used on both etched and unetched porcelain surfaces. Etched relief patterns were observed by means of a scanning electron microscope, and the bond strengths between the photocured composite resin and the porcelain were determined. Scanning electron micrographs revealed complicated etching patterns with increased etching time periods. Shear testing results showed that the bond strength to the unetched porcelain of the composite resin was very low, and that etching periods for more than 30 seconds effectively enhanced the bond strength. Of the two etching agents applied to the unsilanated porcelain, the buffered 2.5% etchant produced higher bond strengths than the 5% etchant for all etching time periods except for 180 seconds. Silane priming was effective and critical for improving bond strength to the porcelain. Application of the silane bonding agent to the porcelain after hydrofluoric acid etching appeared to be suitable for achieving consistent bonding between the composite resin and the porcelain.     

Late fracture of vascularized fibular grafts

There are several causes of erosion - acidic foods and drinks have been implicated and reducing their erosive potential would seem an important area of research. Calcium-citrate-malate (CCM) appeared to have potentially useful properties as an anti-erosion additive. The study aims were to test the ability of an intra-oral enamel slab system to measure erosion and to compare the erosive potential of a citric acid-based orange juice drink either with or without added CCM and a positive and negative control. Eleven adults wore an upper removable appliance for four periods each of 6 days. Each appliance held two enamel slabs which were inserted into the test drinks for 15 min 4 times a day for 6 days. Loss of enamel was quantified by profiling casts of the enamel slabs taken before and after the test period. Loss of enamal was greatest during exposure to a diet phosphoric acid-based cola drink (p < 0.001) but was similar during exposure to the two citric acid-based orange drinks, with or without CCM, and distilled water. The loss of surface enamel measured from a scanning electron micrograph agreed well with the measurement obtained by profilometry. It can be concluded that (a) the intra-oral enamel slab system was able to discriminate between drinks in their erosive potential, and (b) it was not possible to determine if CCM had any potential for reduction in erosion in an acid beverage as the level of erosion observed for both the critic acid-based orange drinks was not statistically significantly different from that observed with distilled water.     

Effects of daily topical fluoride gels on resin composite degradation and wear

OBJECTIVES: This in vitro study compares the effects of professional and consumer-applied topical fluorides on the weight, wear resistance and surface appearance of a resin composite containing barium boroaluminosilicate glass filler particles. METHODS: Prior to wear studies with a pin and disc apparatus, specimens were immersed for 6 min 10 times in water, three consumer-applied topical fluorides (1.1% NaF, 0.4% SnF2, or 0.5% APF gel) or a professionally applied topical fluoride (1.23% APF gel). Specimens were weighed before and after each immersion. Following wear studies, the specimen surfaces were visually evaluated using scanning electron microscopy. Weight changes were analyzed for significant differences using one-way ANOVA and Duncan's multiple range test (p = 0.01). Values of wear parameters were ranked and tested for significance using one-way ANOVA with least squares mean contrast (p = 0.05). RESULTS: Significant differences were found in the weight loss of specimens treated with different fluoride agents: 1.23% APF = 0.5% APF > 0.4% SnF2 > 1.1% NaF = water (p < or = 0.0001). Significant differences in initial wear depth (S(i)) occurred in the following samples: 1.23% APF > 1.1% NaF = 0.5% APF (p = 0.04). Scanning electron micrographs showed variable wear tracks on the specimen surfaces. The specimen surfaces outside the wear track were smooth for those treated with water or with NaF; the surfaces outside the wear track of specimens treated with APF showed extensive loss of filler particles. SIGNIFICANCE: Topical APF agents caused extensive loss of filler from the resin composite specimens whereas 1.1% NaF caused the least damage. Although significant differences in surface wear resistance were detected, clinical studies are needed to determine the effect of topical fluorides on the properties of this resin composite.     

Dental parameters in the long-term survivors of childhood cancer compared with siblings

There have been a number of reports on the dental health of long-term survivors (LTS) of childhood malignancy as compared with normal controls. However, it is usually difficult to identify a meaningful control population as most of these patients are from widely differing geographical areas and socio-economic status. The aim of this investigation was, therefore, to study the dental health of LTS compared with siblings. 46 LTS who had siblings of a similar age were identified for the study. Both groups were examined for dental caries, gingivitis and enamel defects. There was no statistically significant difference in the mean DMFS of the test and control groups. However, the LTS had a significantly (P = 0.006) higher number of decayed surfaces (1.50 +/- 0.30) as compared with their siblings (0.50 +/- 0.20). The LTS also had a significantly higher prevalence of severe gingivitis (1.11 +/- 0.33) compared with controls (0.02 +/- 0.02). There was a significantly higher prevalence of all types of enamel defects in the LTS and fewer teeth with no enamel defect as compared with their siblings, with the mean values being 15.7 +/- 0.9 and 25.3 +/- 0.3, respectively. It was concluded that there was a higher prevalence of untreated dental disease and developmental defects in long-term survivors.     

Repair of Cerec porcelain with seven different systems

Intra-oral repair of fractured porcelain is a challenging clinical necessity, because time, economics, as well as possible trauma to teeth, often contra-indicate replacement of the original restoration. The purpose of this study was to evaluate the bond strength of seven different porcelain repair systems used in combination with Cerec Vitablocs Mark II porcelain. The systems were Scotchbond Multi-Purpose (SMP), All-Bond 2 (AB), Optibond (OB), C&B Metabond (CB), Imperva Bond (IB), Silistor (S) and Mirage Bond (MB). When Mirage Bond was used, the porcelain was either etched with 9.6 percent hydrofluoric acid for 2 min (10 specimens = MB1) or with 4 percent APF gel for 2 min (10 specimens = MB2). The shear bond strengths (SBS) of all the products were determined using an Instron. The effects of the pretreatments on the porcelain with different systems were also examined in a SEM. Data were statistically analysed (Wilcoxon Sum of Rank Test). The mean SBS (MPa) of the products were: SMP = 22.6 +/- 6.5; AB = 17.1 +/- 4.1; OB = 17.1 +/- 2.3; CB = 25.8 +/- 4.2; IB = 18.3 +/- 5.2; S = 16.4 +/- 3.7; MB1 = 13.1 +/- 3.9 and MB2 = 6 +/- 2.1. CB and SMP were significantly stronger (p < 0.05) than all other products, with MB2 statistically weaker (p < 0.01) than the other groups. Most specimens showed cohesive fractures in the porcelain, except when MB was used with 4 percent APF gel, where all samples fractured at the adhesive interface. It can be concluded that all seven systems can be used to repair Cerec Porcelain, except possibly MB when used in conjunction with 4 percent APF etchant.     

Prevalence of developmental enamel defects and dental caries in rural pre-school Thai children

The prevalence of developmental enamel defects and dental caries was assessed in 344 Karen children aged 1-4 years who were chronically (70 per cent) and acutely malnourished (9.3 per cent) The teeth were cleaned with gauze to facilitate detection of hypoplastic lesions on labial surfaces of maxillary incisors. At least one tooth with defective enamel was seen in 31.9 per cent of children, while enamel hypoplasia was present in 22.7 per cent of children. Enamel defects were found in 21.2 per cent of teeth, with hypoplasia and opacities occurring in 14.6 and 6.6 per cent of teeth, respectively. Gender did not alter the prevalence of defects. The upper central incisors were affected more than lateral incisors. The prevalence of dental caries was 31.9 per cent with a mean dt of 1.1. The prevalence of caries associated with enamel hypoplasia was significantly greater than that associated with opacities and sound enamel (P < 0.0005).     

Amalgam alternatives--micro-leakage evaluation of clinical procedures. Part I: direct composite/composite inlay/ceramic inlay

This study investigated the degree of dye penetration with three different types of tooth-coloured restorations. Twenty-four intact extracted molars were collected. The teeth were immediately stored in water at room temperature. Class II cavity preparations were prepared and restored with three different types of tooth-coloured restorations: A, composite resin in the incremental technique; B, composite inlay technique; and C, ceramic inlay. Specimens were subjected to 700 cycles of thermal stress. They were than immersed in 2% basic fuchsin dye. The teeth were sectioned in three planes before being ranked as to the amount of dye penetration. The highest score obtained on three plano-parallel sections was adopted as the representative value. The three groups were compared using the Kruskal Wallis non-parametric test. Dye penetration was significantly lower at the enamel margins when using the composite inlay system and the incremental technique compared to the ceramic inlay technique. The restorations placed using the composite inlay technique showed less dye penetration than the incremental technique at the dentine margins (P < 0.017).     

Arrest of root surface caries in situ

This study tests the hypothesis that daily oral hygiene combined with topical fluoride arrests active root-surface caries lesions without changing the mineral content of the lesions. Therefore, changes in mineral content and distribution were studied in root surfaces during caries lesion development and subsequent arrest of lesion progression in situ. In 18 subjects, lesions were developed during 3 months in sound root-surface specimens inserted into lower partial dentures. After 3 months, ground sections were prepared from each lesion prior to re-insertion of the specimens into the dentures. In addition, one sound root specimen was added per subject. During the following 3 months, half of the subjects cleaned both sound and carious specimens once a day with an 1100-ppm fluoride toothpaste, and the specimens were treated twice with 2% NaF for 2 min in situ. The other half of the subjects continued the experiment without cleaning. During the initial three-month period, all specimens developed subsurface lesions extending 187 to 583 microm into the dentin. Lesion depth increased somewhat in both experimental groups during the following 3 months (P > or = 0.1). There was a non-significant increase in mineral loss in the plaque-covered specimens (P = 0.08). However, the total mineral content of specimens subjected to plaque removal and topical fluoride did not change. This treatment resulted in an increased mineral content in the surface layer (P < 0.01) and formation of a zone of higher mineral content within the body of the lesion. The sound root surfaces which had been cleaned for a three-month period showed mineral uptake in the surface layer, occasionally associated with subsurface demineralization extending 20 to 70 microm into the tissue. The mineral loss of these specimens was significantly smaller than that of plaque-covered surfaces (P < 0.001). It is concluded that daily plaque removal and topical fluoride use influence the distribution of mineral in sound and carious root surfaces and may arrest lesion progression without affecting the total mineral content.     

Coexisting extrapulmonary tuberculosis and malignancy

Electron paramagnetic resonance spectroscopy (EPR) was used to study synthetic hydroxyapatite and approximately 1, 2, and 6% synthetic carbonated apatites, deorganified dentine, and enamel. The carbonated apatites were synthesized by hydrolysis of dicalcium phosphate. Comparisons were made with spectra from enamel and deorganified dentine. Microwave power saturation and dose responses were determined for the synthetic materials. The Marquardt version of the Levenberg decomposition method was used to extract individual signals from the apatite data. Two samples of dentine were irradiated with 25 and 100 Gy, respectively, from a 60Co source. The first sample was then deorganified at 200 degreesC using the Soxhlet extraction technique. A third sample was irradiated with 100 Gy after deorganification. The resulting EPR spectra were then compared. It was determined that the dosimetric signal of 2% synthetic carbonated apatite was approximately the same as that of enamel. It was also verified that the dosimetric signal saturates at about 2% in synthetic carbonated apatites. The study established that the precenters responsible for the dosimetric signal (g perpendicular = 2.0018, g parallel = 1.9985) are preferentially concentrated in the surface-accessible region of the mineral component, as shown by the approximately 80% attenuation of the dosimetric signal in dentine following deorganification. The precenters responsible are not destroyed by the deorganification since the magnitude of the dosimetric signal from the dentine specimen irradiated following deorganification was approximately twice that of the comparable untreated, irradiated sample. Finally, the dose response of 2 and 6% synthetic carbonated apatites was determined.     

Mechanical properties of titanium connectors

The tensile mechanical properties of welded titanium joints were studied, and intact titanium was used as controls. Welded joints were fabricated with either a stereographic laser-welding technique or a gas tungsten arc welding technique. The effect of heat treatment following a simulated porcelain application was also investigated. Heat-treated laser welds had significantly lower ultimate tensile strengths. Heat treatment had no effect on the modulus of elasticity or elongation, but generally significantly decreased the yield strength of the titanium specimens. The gas tungsten are welding specimens had significantly higher yield strengths and elastic moduli than the other two groups. The elongation of the control specimens was significantly greater than the elongation of the gas tungsten arc welding specimens, which was in turn significantly higher than that of the laser-welded specimens.     

Bond strengths and SEM evaluation of Clearfil Liner Bond 2

PURPOSE: To evaluate a dental adhesive system that uses a single conditioning/primer agent. MATERIALS AND METHODS: Twenty-five flat enamel and dentin bonding sites were prepared to 600 grit on human molar teeth. The Clearfil Liner Bond 2 adhesive system was used to bond Clearfil AP-X composite to both enamel and dentin. After 24 hours of water storage, shear bond strengths were determined using an Instron testing machine. Fifty V-shaped cavity preparations were prepared in human molar teeth with an enamel and cementum margin. Composite restorations were placed using the new adhesive system. The teeth were stored for 24 hours, thermocycled, stained with AgNO3 , sectioned and examined for microleakage. SEM examinations were also completed to evaluate the effects of the treatment steps on enamel and dentin surfaces. RESULTS: Mean shear bond strengths for the experimental adhesive to enamel and dentin were 28.2 +/- 4.9 and 19.4 +/- 3.1 MPa. A t-test revealed that the enamel bond strength was significantly greater (P<0.05) than the dentin strength. No marginal leakage was observed from the enamel margins of the restorations. Three restorations showed minimal leakage from the cementum margins. SEM examinations showed resin penetration into both the conditioned enamel and dentin surfaces. The adhesive system produced high bond strengths to both enamel and dentin, exhibited very minimal microleakage and was easy to use.     

Carbonated apatite cement augmentation of pedicle screw fixation in the lumbar spine

STUDY DESIGN: Biomechanical testing with human cadaveric lumbar vertebral bodies was used to determine the utility of an injectable carbonated apatite cancellous bone cement for improving the structural performance of pedicle screws subjected to axial pull-out or transverse cyclic loading. OBJECTIVES: To ascertain whether augmentation with a carbonated apatite cement can enhance pedicle screw fixation in the lumbar spine. SUMMARY OF BACKGROUND DATA: The beneficial effects of polymethylmethacrylate augmentation on pedicle screw pull-out strength have been demonstrated. Cancellous bone cement, however, may provide an attractive alternative in this application, as it is remodelable, biocompatible, and nonexothermic. METHODS: Forty-three cadaveric lumbar vertebral bodies were instrumented with pedicle screws. In 20 of these specimens, axial pull-out strength was compared between the control screws and those augmented with cancellous bone cement. In the remaining 23 specimens, the screws were loaded in the superior-inferior direction with a peak displacement of +/- 1 mm at a frequency of 3 Hz for 5000 cycles. Three parameters were calculated from the force-versus-time data: 1) the energy dissipated, 2) the peak force at the start of the test, and 3) the peak force at the end of 5000 cycles. RESULTS: The pull-out strength of the augmented pedicles averaged 68% greater than that of the control side. In response to cyclic loading, all measures of bio-mechanical performance improved 30-63%. CONCLUSIONS: The data suggest that augmentation with this carbonated apatite cancellous bone cement can enhance immediate screw fixation.