Kurtz Kenneth S
Kurtz Kenneth S
Publications Authored By Kurtz Kenneth S
The prepared tooth was scanned using CAD/CAM technology to fabricate 45 cobalt chromium (CoCr) testing dies. One CoCr die was scanned, and 45 zirconia copings were milled and devided according to the veneering technique into 3 groups of 15 specimens each: layering veneering (LV) using Vita Vm9, overpressing veneering (OV) using Vita Pm9, and digital veneering (DV) using Vita Triluxe forte. All veneering layers had the same shade (A2). The specimens were cemented onto the testing dies using glass inomer cement. A spectrophotometer was used to measure the shade coordinates (L, C, h, a, b) for a Vita A2 shade tab and for each specimen. Both the CIE Lab (ΔEab ) and the CIE DE2000 (ΔE00 ) color difference formulas were applied to compare the shade tab and the study groups. One-way ANOVA and multiple comparison Bonferroni tests were applied for statistical analysis of the results.
Means and standard deviations (SDs) of ΔEab were 2.3 ± 1.3 for LV, 3.5 ± 0.8 for OV, and 4.0 ± 0.7 for DV. Means and SDs of ΔE00 were 1.4 ± 0.8 for LV, 2.1 ± 0.5 for OV, and 3.1 ± 0.4 for DV. ΔEab of LV group was significantly lower (p < 0.05) than both OV and DV groups, whereas the difference in ΔEab between OV and DV groups was not significant (p = 0.39). The differences in ΔE00 between all groups were significant (p < 0.05).
LV group was superior to other groups in terms of shade reproducibility. The ΔEab and the ΔE00 values of LV and OV groups were within clinically acceptable ranges; however, the ΔEab and the ΔE00 values of group DV were beyond the clinically acceptable ranges. The ΔE00 formula demonstrated a statistically significant difference between OV and the DV groups, while the ΔEab formula did not. The zirconia veneering technique had a significant influence on the shade reproducibility of zirconia-based crowns.
The prepared tooth was scanned using CAD/CAM technology to fabricate 45 cobalt chromium (CoCr) testing dies. One CoCr die was scanned, and 45 zirconia copings were milled and divided according to the veneering technique into three groups of 15 specimens each: layering veneering (LV) using Vita Vm9, overpressing veneering (OV) using Vita Pm9, and digital veneering (DV) using Vita Triluxe forte. The crowns were cemented onto the testing dies using glass ionomer cement. The specimens were thermocycled (3000 cycles, 5° to 55°) then statically loaded (3.7 mm ball, 0.5 mm/min crosshead speed) until failure. Failed crowns were inspected using a magnifier, and failure patterns were identified. One-way ANOVA and multiple comparison Bonferroni tests were applied for statistical analysis of the results.
Means and standard deviations of failure loads were 1200 ± 306 N for the LV group, 857 ± 188 N for the OV group, and 638 ± 194 N for the DV group. The differences in failure loads were statistically significant between all groups (p < 0.05). Failure mode was predominantly cohesive for LV and OV groups, whereas it was predominantly adhesive for the DV group.
The LV group was superior to other groups in terms of fracture resistance, while the DV group was inferior to the other groups in the same aspect.
5 and 1.0 mm. Six groups (n = 10) were studied: External- and internal-connection implants with no tissue (control), 0.5, and 1.0 mm of tissue were entrapped at the implant/abutment interface. Abutments were inserted to 20 Ncm for all six groups. Insertion torque values were recorded using a digital torque gauge. All groups were then immersed in 1 M NaOH for 48 hours to dissolve tissue. Subsequent reverse torque measurements were recorded. Mean and standard deviation were determined for each group, and one-way ANOVA and Bonferroni test were used for statistical analysis.
All 60 specimens achieved a 20-Ncm insertion torque, despite tissue entrapment. Reverse torque measurements for external connection displayed a statistically significant difference (p < 0.05) between all groups with mean reverse torque values for the control (13.71 ± 1.4 Ncm), 0.5 mm (7.83 ± 2.4 Ncm), and 1.0 mm tissue entrapment (2.29 ± 1.4 Ncm) groups. Some statistically significant differences (p < 0.05) were found between internal-connection groups. In all specimens, tissue did not completely dissolve after 48 hours.
External-connection implants were significantly affected by tissue entrapment; the thicker the tissue, the lower the reverse torque values noted. Internal-connection implants were less affected by tissue entrapment.
A resorbable collagen membrane was contoured into an ice cream cone- shape, placed into the socket defect, and grafted with human freeze-dried bone allograft. Buccolingual dimensional changes were measured manually with a digital caliper sensitive to 0.01 mm on pre- and posttreatment casts using an acrylic template and a three-dimensional (3D) digital scanner, as well as radiographically with pre- and post-cone beam computed tomography (CBCT) scans. All implants were placed 6 months after socket preservation and achieved primary stability with a minimum torque value of 35 Ncm with a mean buccal-lingual dimensional loss of 1.32 mm. The dimensional change of the ridge from pre- to postextraction reflective of the healed grafted site ranged from a loss of 0.46 to 2.25 mm with a mean of 1.28 mm (CBCT), 0.31 to 2.71 mm with a mean of 1.36 mm (digital calipers), and 0.21 to 2.80 mm with a mean of 1.32 mm (3D digital scanner). All 11 implants were immobile and clinically osseointegrated. The so-called ice cream cone technique allows for the reconstruction of a buccal plate dehiscence to enable the placement of an implant; however, the ridge dimension was diminished by 1.32 mm compared with the width of the extraction socket prior to tooth removal.
An intraoral retentive portion and an extraoral section restoring lip anatomy were attached by retentive elements. This prosthesis restored the patient's esthetics, oral function, and self-esteem.
The stress-breaking ball (SBB) attachment consists of a flat-top ball head male and O-ring rubber female. The female was covered by a silicone housing with three amounts of space to allow three kinds of settlement (0.3 mm, 0.5 mm, and 0.7 mm); they were selected by thickness or pressure displacement of the mucosa and occlusal force. After the healing period, the SBB attachments (0.3 mm) were placed on the implants, and the implant-supported removable partial denture was then conventionally fabricated. The delivered denture had sufficient retention and appropriate stress breaking.
The advantages of SBB attachments over conventional attachments are as follows: (1) they prevent the implant from excessive occlusal force, (2) they are ready-made, (3) they show appropriate retention, and (4) they can be easily mounted on the denture base. The disadvantages of these attachments are as follows: (1) they are approximately 1mm higher than conventional ball attachments and (2) the retentive force cannot be adjusted.
The use of a stress-breaking attachment for implant overdenture rehabilitation should be considered so that the occlusal force is equally distributed between the alveolar ridge and the implants.
The right and left occlusal contact areas were compared after completing the implant-fixed prosthesis rehabilitation.
It has been suggested that accuracy of the impression and maxillomandibular registration is necessary to ensure a satisfactory long-term clinical outcome. The transfer of the exact position of the implants to the working cast is even more important because implants lack the mobility of natural teeth. There are displacement differences between implants and natural teeth under occlusal force. The FBI technique may compensate for this difference in accuracy.
Using the FBI technique, a precise prosthesis could be produced by completing simultaneously the maxillomandibular registration, impression and FGP.
Due to the psychosocial issues confronting these two patients, esthetics was addressed prior to active intervention with orthodontics and after some surgical intervention. The use of two interim overdenture prostheses with magnetic retention is described.
In group B, these positions were reversed. Control specimens were fabricated using all nonengaging components. Specimens were attached to internally connected 3.5 (diameter) × 13 mm (length) implants, torqued to 32 Ncm, and embedded into epoxy resin. Specimens were tested in cyclic fatigue with a 2 Hz sine wave and 0.1 min/max load ratio. Load amplitude started at 1.8 N and increased by 1.8 N every 60 cycles until fracture. Log-rank statistic, ANOVA, Spearman's correlation, and LIFETEST procedures were used to evaluate level of statistical significance within the results.
In the control group, the mean number of cycles to fracture was 31,205 ± 2639. Mean axial force at fracture was 932 ± 78 N. In group A, these numbers were 38,160 ± 4292 and 1138 ± 128 N, and in group B, 31,810 ± 3408 and 949 ± 101 N. Statistical significance levels for number of cycles to fracture were: Control versus group A, p = 0.0117, and groups A versus B, p = 0.0156 (statistically significant). Control versus group B, p = 0.357 (not statistically significant). Log-rank statistic for the survival curves is greater than would be expected by chance; there was a statistically significant difference between survival curves (p = 0.012). The location and mode of failure were noteworthy (always in the abutment screw).
The position of the engaging component had significant effects on the results. Within the limitations of this investigation, it can be concluded that using an engaging abutment in a screw-retained fixed cantilevered FDP provides a mechanical advantage, and engaging the implant furthest from the cantilever when designing a screw-retained cantilever FDP increased resistance to fracture of the distal abutment screw.
Half the specimens were used as control group, and the other half were laser treated circumferentially around the 1.5-mm polished collar with argon shielding. Implants were fatigue tested using a step-stress accelerated lifetime test in a servo-hydraulic test machine. Despite the trend pointing towards higher fatigue resistance of laser treated specimens versus controls, step-stress analysis did not determine significant differences in the fatigue lifetimes.
After laser treatment, tensile testing was conducted to obtain the tensile strength, percent elongation and modulus of elasticity. The hardness depth profile was made from the cast subsurface (25 microm) to 1500 microm in depth using the cross-sections of the cast rods with the same diameter as the dumbbell. The data were statistically analyzed by ANOVA/post hoc tests (p<0.05).
The highest tensile strength was obtained for the titanium specimens laser-treated with 300 V followed by the 240 V and the control specimens. The laser-treated titanium specimens with 300 V showed a tensile strength equivalent to the Co-Cr alloy. Although the highest modulus of elasticity was found for the specimens laser-treated with 240 V, there were no significant differences in elastic modulus among 240 V, 300 V and Co-Cr. The laser-treated groups showed significantly lower hardness at the subsurface of 25 microm and maintained their hardness until the depth of 400 microm. The hardness of the control group was very high at 25 microm depth, and dramatically decreased until the 200 microm depth.
The results of tensile testing and hardness depth-profiling indicated that the laser treatment significantly improved the mechanical properties of cast titanium by improving the surface integrity of the cast surface contamination.
Morita) (prep 3); and (4) airborne-particle abraded with 50-Mum alumina followed by application of the bonding primer for the indirect resin system (Targis Link) (prep 4). A compressive load was applied vertically at 1 mm and 2 mm from the access cavity on the occlusal surface until the restorations failed.
The prep 4 specimens had the highest fracture resistance. The fracture resistance at the 1-mm location was significantly higher than that at the 2-mm location. The failure load of the all-composite restorations with any of the surface preparations was lower than that of the resin-veneered restorations used as controls.
The prep 4 conditions decreased the probability of fracture of the highly filled all-indirect resin composite restorations. Eccentric loading of the all-composite restorations should be minimized in light of the higher probability of failure associated with such a loading condition.
An autopolymerizing denture base resin was applied on the discs within a hole punched in a piece of sticky tape and a Teflon ring to define the bonding area. All specimens were immersed in 37 degrees C water for 24 h. Half of the specimens were thermocycled up to 20,000 cycles. The shear bond strengths were determined at a crosshead speed of 1.0 mm/min.
Specimens treated with the three metal conditioners had significantly (p<0.05) improved shear bond strengths of the autopolymerizing denture base resin to both Ti-6Al-7Nb and Co-Cr. Although the bond strengths of the bonded Ti-6Al-7Nb specimens were higher than those of the Co-Cr alloy before thermocycling, the decrease in the bond strength of Ti-6Al-7Nb was considerably greater than that of the Co-Cr after thermocycling.
Significant improvements in bond strength of the autopolymerizing denture base resin to cast Ti-6Al-7Nb alloy and Co-Cr alloy were achieved through the application of Alloy Primer, Cesead II Opaque Primer and Metal Primer II. The bond durability to Ti-6Al-7Nb alloy was inferior to that to Co-Cr.