Peter Pfeiffer

University of Hamburg, Hamburg, Hamburg, Germany

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Publications (26)38.24 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this in vitro study was to evaluate the shear bond strengths using six intra-oral repair systems intended for bonding composite resin to alloys. Metal plates were fabricated from Au–Ag, Pd–Ag and Co–Cr alloys. Intra-oral repair systems based on tribochemical silica coating (Cojet), mechanical roughening followed by application of silane (Silistor, Cimara, Ceramic Repair) or functional monomer (Metal Primer II) were tested for their ability to bond composite resins to the fabricated alloys, whereas functional monomers (Alloy Primer) were used in combination with Clearfil AP-X resin (five specimens each). After thermocycling shear bond strengths according to ISO 10477 and failure modes were assessed. Statistical analysis was carried out with one-way ANOVA and Bonferroni–Dunn's multiple comparisons post hoc analysis (α = 0.05). Shear bond strengths exceeding 10 MPa were found for Cojet (Au–Ag 13.0 MPa, Pd–Ag 11.6 MPa and Co–Cr 10.3 MPa with Charisma resin (SD 1.2–2.6 MPa); Au–Ag 19.7 MPa, Pd–Ag 14.6 MPa and Co–Cr 10.3 MPa with Pertac Hybrid resin (SD 5.6–6.3 MPa)) and Alloy Primer (Au–Ag 20.9 MPa, Pd–Ag 15.4 MPa, Co–Cr 25.3 MPa (SD 1.4–3.7 MPa)), regardless of the alloy. Alloy Primer and Cojet exhibited the highest shear bond strengths regardless of the alloy and the repair resin (P < 0.05). Most combinations showed resin-metal interfacial failure modes.
    Journal of Adhesion Science and Technology 04/2012; 22(2):133-146. · 0.90 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the effects of a variety of implant cleaning instruments on different implant surfaces, specifically surface roughness and cleaning efficacy. Biofilm layers of Streptococcus mutans were cultivated on titanium disks with four different surface structures (polished, grit-blasted, acid-etched, and acid-etched/grit-blasted). Five disks each were cleaned using nine mechanical implant cleaning instruments or an erbium:yttrium-aluminum-garnet laser. Surface roughness (average, Ra; maximum, Rz) and waviness (Lr) were evaluated by two-dimensional laser profilometry. Surface structure damage and cleaning scores were assessed by scanning electron microscopy. Statistical analyses of the results were performed with one- and two-way analyses of variance and Bonferroni-Dunn multiple-comparison post hoc analysis (α = .05). Ra and Rz values for the acid-etched surfaces and Ra, Rz, and Lr values for the polished and the grit-blasted surfaces showed no significant differences between the different cleaning methods or cleaning instruments compared to the control (not cultured, not cleaned) groups. Significantly lower Ra and Rz values on grit-blasted/acid-etched implant surfaces were found following use of the Sonic-Flex clean with prophylaxis brush and the plastic curette compared to Satelec ProphyMax with Periosoft curette. Ra and Rz values of the different implant structure surfaces before cleaning were significantly different between all implant surfaces except for the polished compared to the acid-etched surfaces. Cleaning effect and alterations of the implant surfaces were strongly dependent on the implant cleaning method used.
    The International journal of oral & maxillofacial implants 03/2012; 27(2):308-17. · 1.91 Impact Factor
  • Peter Pfeiffer, Sandra Bewersdorf, Petra Schmage
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    ABSTRACT: Accuracy of panoramic radiographs is essential for distance measurements during implant planning, but it might be compromised by various factors. The aim of the present study was to evaluate the effect of vertical and horizontal head positioning on area-dependent enlargement ratios of digital panoramic radiography. The mandible of a dry skull was marked with small steel globes. The skull was moved 1 to 4 degrees in 1-degree increments to the left and right and up and down. A series of 17 panoramic radiographs was obtained with the same digital radiographic device. For the rotated skull, horizontal and vertical distances, indicated by the steel globes, were compared to the distances with the ideal positioning of the skull. The results were analyzed statistically. Head positioning and angulation, anatomical site, and distance orientation influenced horizontal measurements. Enlargement ratios of horizontal distances of the right canine and first molar regions (skull rotation to the right 2 to 4 degrees) were significantly lower than those for the corresponding anatomical sites on the left side. Horizontal distance measurements of the different anatomical sites of the left and the right jaw did not differ significantly from each other when the skull was moved downward. When the skull was rotated upward, no significant differences were obtained for corresponding anatomical sites of the right and left arches. Enlargement ratios of vertical distances of different anatomical sites, as well as within the same anatomical site, were not significantly different from each other for the given skull rotations. Ideal head positioning for digital panoramic radiographs is mandatory to avoid improper enlargement ratios of horizontal distances, which can be important in implant dentistry.
    The International journal of oral & maxillofacial implants 01/2012; 27(1):55-63. · 1.91 Impact Factor
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    ABSTRACT: To investigate the effect of a prefabricated tribochemical coating of FRC (fiber-reinforced composite) posts with and without aging on the pull-out forces compared to posts without conditioning. Post space preparations were performed on 108 extracted anterior teeth. Thirty-six uncoated FRC posts (DentinPost) and 72 prefabricated tribochemically coated FRC posts (DentinPost Coated) were used at a length of 12 mm. Thirty-six of the coated posts were thermally aged. FRC posts (n = 9) were placed using DentinBuild or MultiCore Flow foundation composite resins or Panavia F2.0 or RelyX Unicem resin cements. Following water storage (37°, 24 h) and thermocycling (5000 cycles, 5° to 55°C, 30 s), pull-out force testing was performed. Fracture modes were assessed using a light microscope. Data were analyzed statistically (1-way and 3-way ANOVA, Bonferroni-Dunn correction, α = 0.05). Significantly higher pull-out forces of posts luted with Panavia F2.0 were observed for the coated and coated/aged FRC posts compared to the unconditioned posts (control group, p < 0.001). The pull-out forces of tribochemically coated FRC posts luted with MultiCore Flow were significantly lower than of coated posts luted with Panavia F2.0 (p < 0.001). Coated/aged FRC posts exhibited similar pull-out forces for the tested luting composite resins (p > 0.05). Except for DentinBuild (coated posts), more mixed or cohesive fractures were assessed for coated and coated/aged FRC posts than for unconditioned FRC posts. Prefabricated tribochemical coating of FRC posts provided a stable interface between coating and post and remained stable over time.
    The journal of adhesive dentistry 11/2011; 14(2):175-82. · 0.91 Impact Factor
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    ABSTRACT: The aim of this study was to determine the retentive forces of fiber-reinforced composite (FRC) posts luted with different core build-up composite resins, and resin cements. Extracted single-rooted teeth were restored using FRC posts luted with the core build-up composites Build-It, Culmat, Flow White, Luxacore, Multi-Core Flow, Rebilda DC and luted with the resin cements Calibra, Cement-It, Multilink, and RelyX Unicem (control group, no separate etching, priming or bonding steps). The Rebilda DC was used with both the light-polymerizing Solobond and the dual-polymerizing AdheSE. Following water storage (37°C, 24 h) and thermal cycling (5000 cycles, 5–55°C, 30 s) tensile strength testing was performed and fracture modes were assessed. Statistical analysis of the data was done by one-way ANOVA, Bonferroni/Dunn correction, and unpaired t-test with α = 0.05. Except for Multilink (319 N, SD 50 N) and Cement-It (331 N, SD 85 N) significantly higher retentive forces were obtained for the core build-up composite Build-It (422 N, SD 43 N) and for the resin cements Calibra (408 N, SD 50 N) and RelyX Unicem (405 N, SD 64 N) compared to the other materials (p < 0.001). The lowest retentive forces were found for the core build-up composites Luxacore (145 N, SD 36 N) and Rebilda DC/Solobond (148 N, SD 39 N) (p < 0.001). Fracture modes were mainly interfacial. The use of core build-up composites did not improve the retentive forces of FRC posts compared to resin cements. Except for Culmat, core build-up composites as well as resin cements in combination with dual-polymerizing bonding materials were superior to composites with light-polymerizing bonding materials.
    Journal of Adhesion Science and Technology 01/2011; 25(16):2023-2038. · 0.90 Impact Factor
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    ABSTRACT: Debonding is a common cause of failure encountered with fiber-reinforced composite (FRC) posts, and usually occurs along the post space-dentin adhesive interface. Surface conditioning of posts is expected to increase the chemical and mechanical bond between the luting composite resin and the post, but the best method has not been definitively determined. The purpose of this in vitro study was to compare the effects of 3 surface-conditioning methods on the retentive bond strengths of FRC posts using 5 composite resin materials, and compare results to those of unconditioned FRC posts as well. Post space preparations (DentinPost ER root post system, length of 12 mm) were performed on 200 human anterior teeth. Groups of 50 FRC posts (ISO size 90) each were treated using 1 of the following conditioning methods: silanization, etching with 5% hydrofluoric acid, tribochemical coating (CoJet system), or were left untreated (control group). FRC posts (n=10) in each group were placed using 1 of 5 composite resin materials (Calibra or RelyX Unicem resin cements or Build-It, MultiCore Flow, or Rebilda DC foundation composite resins). Following water storage (37 degrees C, 24 hours) and thermal cycling (5000 cycles, 5 degrees -55 degrees C, 30-second dwell time), tensile strength testing was performed. Fracture modes were assessed using a light microscope. Data were analyzed statistically (1-way and 2-way ANOVA, Bonferroni-Dunn correction, alpha=.05). Retentive bond strengths of FRC posts luted with MultiCore Flow in combination with the CoJet system, and of posts inserted with Rebilda DC in combination with hydrofluoric acid (HF) etching as well as with the CoJet system, were significantly higher than those of the corresponding unconditioned FRC posts (P<.001). No significant differences were noted between the bond strength values of RelyX Unicem with CoJet, MultiCore Flow with CoJet, and Rebilda DC with either CoJet or HF etching (P>.05). Retentive bond strengths were significantly lower for HF etching (Calibra, RelyX Unicem, Build-It), and for the treatment with the CoJet system in combination with Build-It compared to the corresponding control groups (P<.001). Fracture modes were primarily adhesive at the post surface or cohesive within the composite resin layer or within the FRC post. The retentive bond strengths differed significantly with respect to the tested combinations of conditioning method and luting composite resin.
    The Journal of prosthetic dentistry 12/2009; 102(6):368-77. · 1.22 Impact Factor
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    ABSTRACT: Currently, glass fiber-reinforced composite (FRC) posts with shank heads are only recommended for moderate coronal defects. Restoring endodontically treated teeth with large coronal defects remains a challenge, requiring posts with coronal retention and high bending resistance. The purpose of this in vitro study was to investigate the yield strengths of FRC posts and titanium posts (TI) with coronal retention for core foundations compared to FRC and TI posts without coronal retention. Tapered posts (ER root post system) of 4 diameters (ISO 50, 70, 90, 110), 2 lengths (tapered part: 9 and 12 mm) of identical shape, 2 materials (FRC, titanium), and 2 head designs (shank without retention (SH) and post head with horizontal retention (RET)) were evaluated (n=9). Titanium posts (TI-SH, TI-RET) served as the control. The 0.2% yield strengths (R(0.2)) of all specimens were tested in a universal testing machine. Three-way and 1-way ANOVAs with Bonferroni-Dunn's multiple comparison tests were performed (alpha=.05). The yield strengths of the control groups TI-RET were significantly higher for ISO 110 with a 9-mm length and for ISO 70 and 110 with a 12-mm length, compared to the respective FRC-RET posts (P<.001), whereas in all other groups, TI-RET and FRC-RET showed no significant differences. FRC-SH groups did not differ from FRC-RET groups. TI-SH showed significantly lower yield strength for ISO 70 compared to TI-RET, but significantly higher values for ISO 90 and 110 (P<.001). Head design of the tested FRC posts does not improve the yield strength, compared to FRC posts with a shank design. The diameter of the posts had a significant effect on the yield strengths of RET as well as SH groups.
    The Journal of prosthetic dentistry 06/2009; 101(6):382-7. · 1.22 Impact Factor
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    ABSTRACT: This study compared the bond strengths of fiber-reinforced composite (FRC) posts luted into oversized dowel spaces with FRC posts luted into precisely fitting dowel spaces using five different resin cements or build-up composites. The hypotheses examined were that bond strength does not present vast variations according to the width of the gap between the root canal and post and that bond strength increases for FRC posts luted with build-up composites compared with FRC posts luted with resin cements. Dowel space preparations (ER post-restoring system, 12 mm in length) were performed on 100 human anterior teeth up to ISO 90 and ISO 110 of 50 roots each. FRC posts, all ISO size 90, were inserted into the precisely fitting as well as into the oversized dowel spaces (n = 10) using five composite materials (Calibra, Multicore Flow, Rely X Unicem; resin cements and Build-It, Rebilda DC; build-up composites). The manufacturers' instructions of the composite materials were strictly followed except for Rebilda DC, which was used with Adhese for dentin bonding. Following water storage (37 degrees C, 24 hours) and thermocycling (5000 cycles, 5 degrees C-55 degrees C, 30 seconds) tensile strength testing was performed and fracture modes were assessed using SEM. Data were analyzed statistically (one-way and two-way ANOVA, Bonferroni/Dunn correction, alpha < 0.05). The retentive bond strengths of FRC posts in oversized dowel spaces decreased significantly for all luting composites except for Rebilda DC, compared with the respective groups with precise fitting (p < 0.011). Yet, the bond strengths of RelyX Unicem (454 N +/- 64 N), Build-It (422 N +/- 43 N) and Calibra (408 N +/- 50 N) showed significantly higher values for the precisely fitting posts than Rebilda DC (267 N +/- 54 N). RelyX Unicem revealed significantly higher values than Multicore Flow (296 N +/- 73 N). The bond strengths of FRC posts in oversized dowel spaces varied from 301 N +/- 78 N for Build-It to 152 N +/- 37 N for Calibra. The values of Build-It were significantly higher compared with Calibra, Multicore Flow (180 N +/- 47 N) and Rebilda DC (186 N +/- 52 N), as well as those of RelyX Unicem (256 N +/- 115 N) were significantly higher than Calibra. Fracture modes were shown to be mainly adhesive at the post surface or cohesive for precisely fitting posts and to occur between post and composite except for RelyX Unicem with cohesive fractures for the oversized dowel spaces. The build-up composite Build-It showed superior bond strengths in oversized canals, which were still not as high as those of posts in precisely fitting dowel spaces using common resin cements.
    Operative Dentistry 01/2009; 34(1):93-101. · 1.31 Impact Factor
  • Peter Pfeiffer, Natalie An, Petra Schmage
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    ABSTRACT: Hypoallergenic denture base materials are commonly used for patients with allergic reactions to polymethyl methacrylate (PMMA) denture base materials. The goal for repaired fractured dentures fabricated from hypoallergenic denture base materials is to restore the dentures to their original strength. The purpose of this in vitro study was to investigate the flexural properties of 7 hypoallergenic denture base materials after repair compared with a conventional PMMA-based heat-polymerizing resin. Specimens (n=5) of the following hypoallergenic denture base materials with differing polymerization modes: Eclipse base material, Luxene, Microbase, Polyan, Puran HC, Alldent Sinomer, and The.r.mo.Free, were repaired with Versyo.com as well as the respective repair systems for 4 of the tested materials. A heat-polymerized acrylic resin (Paladon 65) was repaired using autopolymerizing acrylic resin (Palapress), which served as the control. Flexural strengths (MPa) and flexural moduli (MPa) were assessed before and after repair of each material, according to ISO 1567. The data were analyzed with repeated measures 2-way and 3-way ANOVA, 1-way ANOVA, and Bonferroni-Dunn's multiple comparisons post hoc analysis, or with the paired t test (alpha=.05). Flexural strengths and flexural moduli of both repair methods (repair according to manufacturer's instructions or repair with Versyo.com) for all materials were significantly lower than those of the intact specimens (P<.001). Alldent Sinomer and The.r.mo.Free repaired with Versyo.com showed flexural strengths comparable to the intact material. The flexural modulus of Puran HC, Alldent Sinomer, and The.r.mo.Free repaired with Versyo.com did not differ significantly from the original, nonrepaired material. No significant differences were noted between the flexural strength (P=.616) and the flexural modulus (P=.138) values regarding the 2 repair methods of the respective materials. None of the repaired hypoallergenic denture base materials demonstrated significantly higher flexural strengths than repaired Paladon 65. Flexural strengths of repaired Puran HC and Alldent Sinomer were significantly lower than those of repaired Paladon 65 specimens (P<.001). Flexural moduli of repaired Puran HC, Alldent Sinomer, and The.r.mo.Free showed a significant decrease compared to the repaired Paladon 65 specimens (P<.001). Eclipse and Luxene passed the flexural property requirements of ISO 1567 before and after repair. No significant influence of the repair systems was found, but the flexural properties of the repaired materials differed significantly with respect to the tested acrylic resins.
    The Journal of prosthetic dentistry 11/2008; 100(4):292-301. · 1.22 Impact Factor
  • P Pfeiffer, L Grube
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    ABSTRACT: This in vitro study evaluated the fracture load of interim FPDs made with various materials and pontic heights. The hypothesis was that different materials and pontic heights result in different fracture resistance. Groups of interim FPDs were fabricated with prosthodontic resin materials on two abutments with two different pontic heights (4.3 and 5.8 mm) and a pontic width of 4 units (19 mm) (n = 3). The following materials were tested: (1) a thermoplastic polymer (Promysan Star), (2) Promysan Star with a veneering composite (Vita Zeta), (3) a non-impregnated polyethylene fiber reinforced resin (Ribbond) with a veneering composite (Sinfony), (4) an impregnated fiber reinforced composite system (Targis/Vectris), and (5) a conventional poly methyl methacrylate (PMMA) (Biodent K+B, control group). After 5000 thermocycles, the FPDs were temporarily fixed with a provisional cement on the corresponding abutments and tested for fracture strength. One-way and two-way ANOVA and Bonferroni-Dunn's multiple comparison tests were performed for the statistical analysis (alpha = 0.05). The mean fracture strength ranged from 83.0 to 625.9 N for a pontic height of 4.3 mm and from 97.2 to 893.7 N for a pontic height of 5.8 mm. Vectris/Targis FPDs of both pontic heights exhibited significantly superior fracture resistance compared to the corresponding Promysan, Promysan/Vita Zeta, Ribbond/Sinfony and Biodent groups. Except Biodent FPDs, fracture resistance of FPDs with a pontic height of 4.3 mm showed no significant differences compared to a pontic height of 5.8 mm for each material. Material type of the FPDs has a significant influence on the fracture strength, whereas pontic height has no significant effect (except control group).
    Dental Materials 01/2007; 22(12):1093-7. · 3.77 Impact Factor
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    ABSTRACT: In fixed prosthodontics, fracture of the porcelain veneer is not an uncommon problem under clinical conditions due to, e.g., malfunction, trauma or technical failures. To avoid time-consuming and cost-intensive renewal of the entire restoration, repair of the chipped veneer is desirable. The aim of this in vitro study was to evaluate the shear bond strengths of five intraoral porcelain repair kits based on different chemical bonding systems. 45 metal plates veneered with feldspathic porcelain were fabricated. The surface treatment was performed using five porcelain repair systems based on tribochemical silica coating (Cojet), mechanical roughening (Silistor, Cimara, Ceramic Repair) or etching (Clearfil Repair) followed by application of silane coupling agents (five specimens each). Cylinders of composite resin of Charisma and Pertac Hybrid were bonded using Cojet, Silistor, Cimara and Ceramic Repair, and of Clearfil AP-X with Clearfil Repair onto the porcelain specimens. After thermocycling (5000 cycles, 5–55°C) shear bond strength was measured according to ISO 10477 followed by assessment of the failure mode. Statistical analysis was carried out with one-way ANOVA and Bonferroni–Dunn's multiple comparisons post-hoc analysis for test groups (α = 0.05). Shear bond strengths higher than 10 MPa were found for all test groups except for Ceramic Repair with Pertac Hybrid (8.1 ±1.3 MPa), which was significantly lower than all other groups (P < 0.05). Highest shear bond strength was found for Silistor with Charisma (23.1 ± 5.8 MPa), which was significantly higher (P < 0.05) than all other groups except Cojet with Charisma (17.8 ± 3.6 MPa) and Clearfil Repair (20.3 ± 5.0 MPa). Cojet and Silistor with Charisma, Cimara, as well as with Clearfil mainly showed cohesive or mixed failure modes (cohesive and interfacial). Bond strengths of the combinations Silistor-Charisma, Clearfil Repair-Clearfil AP-X and Cojet-Charisma were superior to all other combinations used in the present tests.
    Journal of Adhesion Science and Technology 01/2007; 21:409-422. · 0.90 Impact Factor
  • P Pfeiffer, P Schmage, A Schulz, I Nergiz
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    ABSTRACT: The aim of this in vitro study was to evaluate the bending resistance of unit cast posts-and-cores (UPC) and prefabricated high noble posts with cast-on cores. Tapered posts (ER post-restoring system) of three sizes in diameter (ISO 50, 90, 110) were investigated: UPC were cast of three different alloys (Au-Pt-Pd, Au-Ag-Pt, Co-Cr-Mo). Also, prefabricated tapered noble posts (Heraplat and Pt-Ir) were cast over with metal cores of the different alloys. Prefabricated titanium posts of each size were precision fit into the central core channels of the Co-Cr-Mo cores to serve as control specimens. The 0.2% yield strengths (R(0.2)) of all specimens were tested on a universal testing machine. One-way and three-way anova and Bonferroni-Dunn's multiple comparison tests were performed for the statistical analysis. The mean bending resistance R(0.2) of the unit cast posts-and-cores was 45 +/- 4-46 +/- 5 N for ISO 50 (control group: 54 +/- 3 N), 91 +/- 9-93 +/- 7 N for ISO 90 (control group: 117 +/- 11 N) and 115 +/- 13-130 +/- 12 N for ISO 110 (control group: 141 +/- 12 N). Except for the Au-Pt-Pd UPC of ISO 110, the yield strengths of the control groups were significantly superior to all unit cast alloy combinations (P < 0.05). Significantly lower bending resistance was found for Co-Cr-Mo cores cast over Heraplat and Pt-Ir posts compared with the corresponding Heraplat/Au-Ag-Pt, Heraplat/Au-Pt-Pd and Pt-Ir/Au-Ag-Pt posts-and-cores.
    Journal of Oral Rehabilitation 02/2006; 33(2):125-30. · 2.34 Impact Factor
  • P Pfeiffer, A Schulz, I Nergiz, P Schmage
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    ABSTRACT: The aim of this in vitro study was to evaluate the yield strengths of glass fibre-reinforced composite (FRC) posts and zirconia dioxide ceramic (ZDC) posts. Tapered glass FRC posts (DentinPost) and ZDC posts (Cerapost) of three sizes in diameter (ISO 50, 90, 110) were used for bending tests. Conventional prefabricated titanium posts of the same sizes served as control groups. The 0.2% yield strengths (R(0.2)) were tested on a universal testing machine. As zirconia posts fractured before they were yielded 0.2%, the fracture strength instead of the yield strength was recorded for these posts. One-way and two-way anova and Bonferroni-Dunn's multiple comparison tests were performed for the statistical analysis. The mean 0.2% yield strengths of the posts were 27 +/- 1 N for glass fibre-reinforced posts and 58 +/- 4 N for zirconia posts of ISO 50 (control group: 54 +/- 3 N). For ISO 90 yield strengths of 52 +/- 4 N for glass fibre-reinforced posts, 117 +/- 20 N for zirconia posts and 117 +/- 11 N for the control group were obtained. For ISO 110 mean yield strengths amounted to 73 +/- 5 N for glass fibre-reinforced posts, 166 +/- 23 N for zirconia posts and 141 +/- 12 N for the control group. Significantly higher yield strength was recorded for the zirconia and the titanium posts compared with the glass fibre-reinforced posts for the tested ISO sizes.
    Journal of Oral Rehabilitation 02/2006; 33(1):70-4. · 2.34 Impact Factor
  • Peter Pfeiffer, Christian Rolleke, Lamia Sherif
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    ABSTRACT: Hypoallergenic denture base materials show no residual methyl methacrylate (MMA) or significantly lower residual MMA monomer content compared to polymethyl methacrylate-based (PMMA) heat-polymerizing acrylic resin. There is insufficient knowledge of the mechanical properties of hypoallergenic denture base materials to warrant their use in place of PMMA-based acrylic resins for patients with allergic reaction to MMA. This in vitro study compared flexural strength and flexural modulus of 4 hypoallergenic denture base materials with flexural strength/modulus of a PMMA heat-polymerizing acrylic resin. The following denture base resins were examined: Sinomer (heat-polymerized, modified methacrylate), Polyan (thermoplastic, modified methacrylate), Promysan (thermoplastic, enterephthalate-based), Microbase (microwave-polymerized, polyurethane-based), and Paladon 65 (heat-polymerized, methacrylate, control group). Specimens of each material were tested for flexural strength and flexural modulus (MPa, n = 5) according to ISO 1567:1999. The data were analyzed with 1-way analysis of variance and the Bonferroni-Dunn multiple comparisons post hoc analysis for each test variable (alpha=.05). Flexural strength of Microbase (67.2 +/- 5.3 MPa) was significantly lower than Paladon 65 (78.6 +/- 5.5 MPa, P <.0001). Flexural strength of Polyan (79.7 +/- 4.2 MPa, P =.599), Promysan (83.5 +/- 3.8 MPa, P =.412), and Sinomer (72.3 +/- 2.1 MPa, P =.015) did not differ significantly from the control group. Significantly lower flexural modulus was obtained from Sinomer (1720 +/- 30 MPa, P =.0007) compared to the PMMA control group (2050 +/- 40 MPa), whereas the flexural modulus of Promysan (2350 +/- 170 MPa, P =.0005) was significantly higher than the PMMA material. Microbase (2100 +/- 210 MPa, P =.373) and Polyan (2070 +/- 60 MPa, P =.577) exhibited flexural modulus similar to the PMMA material. The tested denture base materials fulfilled the requirements regarding flexural strength (>65 MPa). With the exception of Sinomer, the tested denture base resins passed the requirements of ISO 1567 regarding flexural modulus (>2000 MPa). Flexural modulus of Promysan was significantly higher than the PMMA material. Microbase and Sinomer exhibited significantly lower flexural strength and flexural modulus, respectively, than PMMA. The other groups did not differ significantly from the control group.
    Journal of Prosthetic Dentistry 04/2005; 93(4):372-7. · 1.72 Impact Factor
  • H-B Lindemann, C Knauer, P Pfeiffer
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    ABSTRACT: The shape of a patient's face is commonly used as a reference to select the shape of the maxillary central incisors in edentulous patients. The validity of this relationship has not been proved. The objective of this clinical study was to determine whether a relationship exists between maxillary central incisors and face shapes. Casts were made of the maxillas of 50 men and 50 women. A standardized digital photographic procedure was used to record frontal views of each subject's face and of the maxillary central incisors of the dental casts. The shapes of the maxillary central incisors were compared with the face forms. Shape matches were evaluated according to their Hausdorff distance (HDD). The function h(A,B) is called the directed HDD from shape A to shape B (this function is not a true distance). It reflects the distance of the point of shape A that is farthest from any point of shape B and vice versa. The similarity of both shapes is given as a non-negative number. The value 0.0 indicates that the figures are identical (after scaling and shifting). Higher values indicate that shapes differ more substantially. Significant differences on the 5% level were calculated using the non-parametric Mann-Whitney U and Kruskal-Wallis tests. The face shape from the chin margin to the eyebrow line (superior edges of the eyebrows) produced a better match than the one from the chin to the hairline (P < 0.0001). On average, the maxillary central incisors displayed a variability (0.084 +/- 0.028) that was higher by a factor of 1.9 than the face shapes (chin margin to the eyebrow line, 0.045 +/- 0.015). In the interindividual comparison, the shapes of the maxillary central incisors of women displayed a significantly smaller HDD than the ones of the men (P < 0.0001).
    Journal of Oral Rehabilitation 10/2004; 31(10):972-8. · 2.34 Impact Factor
  • Peter Pfeiffer, Ernst-Ulrich Rosenbauer
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    ABSTRACT: Denture base materials have the potential to cause irritation and allergic reaction to the oral mucosa. Water sorption and water solubility of denture base resins affect dimensional behavior and denture stability. A correlation between residual monomer and water sorption exists. This in vitro study compared the amount of residual monomer, quantity of water sorption, and solubility of 4 denture base materials purported to be hypoallergenic with those of a polymethyl methacrylate-based (PMMA) heat-polymerizing acrylic resin. The denture base resins Sinomer (heat-polymerized, modified methacrylate), Polyan (thermoplastic, modified methacrylate), Promysan (thermoplastic, enterephthalate-based), and Microbase (microwave polymerized, polyurethane-based), which are purported to be hypoallergenic, and Paladon 65 (heat-polymerized, methacrylate, control group) were examined. Specimens of each material were tested for residual methyl methacrylate (MMA) monomer (% wt, n=3), amount of water sorption (microg/mm3, n=5) and water solubility (microg/mm3, n=5), according to ISO 1567:2000. The residual MMA monomer concentrations were determined by gas chromatography (GC). The data were analyzed with 1-way ANOVA and the Bonferroni-Dunn multiple comparisons post hoc analysis for each test variable (alpha=.05). Significantly lower residual MMA monomer was shown for Sinomer and Polyan compared to the PMMA control group (0.90 +/- 0.20% wt, P<.05). Sinomer contained 0.31% +/- 0.00% wt MMA monomer, and Polyan exhibited residual MMA monomer content of 0.44% +/- 0.01% wt. Promysan and Microbase did not contain detectable residual MMA. Water sorption of Promysan (16.21 +/- 0.96 microg/mm3) was significantly lower than Paladon 65 (23.04 +/- 3.13 microg/mm3, P<.0001), whereas water solubility of the hypoallergenic denture base materials (0.34-0.84 +/- 0.05-0.09 microg/mm3) was not significantly lower than the PMMA material (0.40 +/- 0.06 microg/mm3, P>.05). Except for Sinomer, the tested denture base resins passed the requirements of ISO 1567 regarding residual MMA monomer (<2.2% wt). Sinomer failed to comply with the requirements for residual MMA monomer because the manufacturer claimed that the material did not contain any MMA. The tested denture base materials fulfilled the requirements regarding water sorption (<32 microg/mm3) and solubility (<1.6 microg/mm3). The tested hypoallergenic denture base materials exhibited significantly lower residual monomer content than PMMA. Promysan and Microbase showed no detectable residual MMA.
    Journal of Prosthetic Dentistry 07/2004; 92(1):72-8. · 1.72 Impact Factor
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    ABSTRACT: Posts and cores are used to restore endodontically treated teeth that have substantial loss of the coronal tooth structure. This in vitro study was designed to determine the mechanical properties of prefabricated titanium posts following attachment of their metal cores by molten casting (caston). Prefabricated tapered titanium posts (ER post-restoring system, Komet, Lemgo, Germany) in three diameter sizes (ISO 50, 90, 110) (n=9) were cast over with the metal cores of three different alloys (Au-Ag-Pt, Au-Pt-Pd, Co-Cr-Mo). Also, posts of each size were precision fit into the central core channels of the different cast metal cores to serve as control specimens. The 0.2% yield strengths (R0.2) of all specimens were tested on a universal testing machine. Statistical analyses of the results were carried out with an analysis of variance (ANOVA, one-way, two-way) and Bonferroni-Dunn's multiple comparisons post-hoc analysis for test groups (alpha=0.05). There was a significant decrease in yield strength (p<0.05) as a result of casting the various metals over the different post sizes, considered to be due to the detrimental thickening and porosity formation of the titanium surface oxide layer. Twenty-one percent, 51% and 33% reduction in yield strength, respectively, was obtained for the ISO 50, ISO 90 and ISO 110 cast-on groups relative to controls (p<0.05). Statistically significant differences in various core alloys were found only for the Au-Ag-Pt alloy compared to the Co-Cr-Mo alloy (post size ISO 50) and the Au-Pt-Pd alloy compared to the Co-Cr-Mo alloy (post size ISO 110) (p>0.05). Prefabricated titanium posts with metal cores cast over them showed inferior mechanical properties compared to precision-fit posts. These results indicate greater strength of the titanium posts when their cast cores were attached mechanically rather than by the molten casting method.
    Operative Dentistry 01/2004; 29(4):404-9. · 1.31 Impact Factor
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    ABSTRACT: During fabrication or repair of removable partial dentures, resin-to-metal or resin-to-denture tooth bonds may be stressed by laboratory procedures. The purpose of this in vitro study was to evaluate the effect of steam cleaning, boiling, ultrasonic cleaning (laboratory procedures), and thermocycling on shear bond strength of resin bonds to metal and denture teeth. Resin-metal bonding systems and their specific veneer resins (Rocatec, Sinfony; Rocatec, Visio-Gem, HLC-BOND, Zeta LC and Ducera experimental veneer resin) were tested on a Co-Cr alloy (Wirobond C). The veneer resins were bonded to resin denture teeth. The experimental groups (n=7) were subjected to the following conditions: 24-hour storage of the specimens in air (group I, control group), storage in air and treated with simulated laboratory procedures (2 minutes steam cleaning, 15 minutes ultrasonic cleaning at room temperature, 1 hour boiling in water, group II), storage in air with thermocycling (5000 cycles, 5 degrees to 55 degrees C, group III), storage in air with laboratory procedures followed by thermocycling (group IV), and storage in air with thermocycling followed by laboratory procedures (group V). Shear strength tests (MPa) were performed with a universal testing machine until fracture. After shear bond testing, the failure mode of the resin-metal and resin-denture tooth bonds was assessed. Statistical analysis of the results was carried out with one-way analysis of variance and Bonferroni-Dunn's multiple comparisons post hoc analysis for test groups (alpha=0.05). Except for Ducera/denture tooth specimens (groups III to V: 8.7 +/- 3.4-9.1 +/- 1.7; 10.8 +/- 1.9 MPa control group), the Wirobond C and denture tooth specimens (groups III, IV and V: 1.4 +/- 0.9-11.9 +/- 2.3 MPa), showed significantly lower shear bond strengths than the corresponding control groups (7.5 +/- 2.9-21.0 +/- 3.4 MPa, P<.05). The shear bond strengths of group II of Sinfony/Wirobond C (11.6 +/- 3.3 MPa, P<.0001), Visio-Gem/Wirobond C (7.4 +/- 1.9 MPa, P<0.0001), Ducera/Wirobond C (11.8 +/- 2.9 MPa, P<.0001) and of Zeta/denture tooth (3.9 +/- 1.6 MPa, P=.0005) were significantly decreased by steam, boiling, and ultrasonic procedures compared with the corresponding control groups (21.0 +/- 3.4 MPa; 14.7 +/- 4.0 MPa; 19.1 +/- 2.3 MPa; 7.5 +/- 2.9 MPa, respectively). No significant differences were noted among groups III, IV, and V. Co-Cr specimens subjected to the Rocatec system and bonded with Sinfony and HLC BOND/Zeta specimens showed cohesive failure. Adhesive failure was observed for the experimental veneer resin on the Co-Cr specimens and for all veneer resins on the denture teeth. Simulation of laboratory procedures and thermocycling caused a significant drop in shear bond strength of metal-resin and denture tooth-resin bonds for most of the tested veneer resins. Thermocycling before shear testing had the same effect on veneer resin bond strength as the simulated laboratory procedures.
    Journal of Prosthetic Dentistry 08/2003; 90(2):184-9. · 1.72 Impact Factor
  • Peter Pfeiffer, Lars Grube
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    ABSTRACT: Comprehensive restorative dental treatment often necessitates the use of interim fixed partial dentures (FPDs) with high stiffness, especially in long-span restorations or areas of heavy occlusal stress. This in vitro study evaluated the fracture load of interim FPDs made with various materials and span lengths. Groups (n = 3) of interim FPDs were fabricated with prosthodontic resin materials on 2 abutments with 3 different pontic widths of 3 units (12 mm), 4 units (19 mm), and 5 units (30 mm). The following materials were tested: (1) a thermoplastic polymer (Promysan Star), (2) Promysan Star with a veneering composite (Vita Zeta), (3) a nonimpregnated polyethylene fiber reinforced resin (Ribbond) with a veneering composite (Sinfony), (4) an impregnated fiber reinforced composite system (Targis/Vectris), and (5) a conventional polymethyl methacrylate, Biodent K+B, (control group). After 5000 thermocycles in 2 water baths at 5 degrees and 55 degrees C, the FPDs were temporarily fixed with a provisional cement on the corresponding abutments and subjected to 3-point bending until fracture by a universal testing machine. Statistical analysis consisted of an analysis of variance (ANOVA, 1-way, 2-way) and Bonferroni-Dunn's multiple comparisons post hoc analysis for test groups (alpha = .05). Fracture resistance (N) differed significantly for 3 (mean: 640 +/- 146 N), 4 (626 +/- 229 N), and 5 unit (658 +/- 98 N) Targis/Vectris FPDs compared with the corresponding Promysan (284 +/- 21 N to 125 +/- 73 N), Biodent K+B (247 +/- 91 N to 218 +/- 85 N), and Promysan/Vita Zeta (95 +/- 15 N to 82 +/- 6 N) groups (P < .05). Significant differences were obtained for the 4 and 5 unit Targis/Vectris FPDs compared with the Sinfony/Ribbond FPDs (281 +/- 25 N - 252 +/- 74 N) for the corresponding pontic spans. Within the limitations of this in vitro study the impregnated fiber reinforcement may considerably enhanced the fracture resistance of interim FPDs of different span lengths.
    Journal of Prosthetic Dentistry 02/2003; 89(2):170-4. · 1.72 Impact Factor
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    M Ozcan, P Pfeiffer, I Nergiz
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    ABSTRACT: The advantage of using ceramic inserts is to prevent major drawbacks of composite resins such as polymerization shrinkage, wear and microleakage. This in vitro study evaluated the marginal adaptation of two approximal ceramic insert systems after cementation to the cavities opened with ultrasonic tips. Proximal cavities with margins in enamel were prepared in 20 intact molars using ultrasonic tips (SONICSYS approx tips [microtorpedo size #2 and #3]; Siplus Instrument approximal [U-shaped]). Inserts of similar sizes (n=10) from two systems corresponding to the ultrasonic tips were placed in the cavities (SONICSYS Inlay; SDS-Inlay system), one on the mesial side and the other on the distal side of the same molar. Following cementation and thermocycling (5000 cycles, between 5-55 degrees C), cement thickness was measured at the buccal, lingual walls and pulpal floors of the proximal boxes under light microscope (x150). The mean cement thickness values recorded for SONICSYS inserts #2 (25 microm) was not significantly different (p>0.05) from that of SDS inserts of similar size (26 microm). There was a significant difference (p<0.05) in cement thickness values between SONICSYS #3 inserts (34 microm) and SDS inserts of similar size (23 microm). Comparison of mean values between the ceramic insert systems examined revealed that marginal adaptation was better at the buccal and lingual proximal walls than those at the pulpal floor in the SDS system, however, there was no difference for SONICSYS at both sizes. Ceramic inserts placed in cavities prepared with ultrasonic tips provide clinically acceptable marginal quality.
    Operative Dentistry 01/2002; 27(2):132-6. · 1.31 Impact Factor