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Maxillary Premolars (maxillary + premolar)
Selected AbstractsIn vivo degradation of collagen barrier membranes exposed to the oral cavityCLINICAL ORAL IMPLANTS RESEARCH, Issue 8 2010Avigdor Klinger Abstract Objectives: The purpose of this human clinical trial was to compare the degradation profiles of three different collagen membranes under conditions mimicking exposure to the oral cavity. Materials and methods: Three collagen membranes, ribose cross-linked (RCL), glutaraldehyde cross-linked (GCL), and non-cross-linked (NCL) were tested. The membranes were placed over the buccal mucosa of 20 human volunteers, apical to the gingival margins in the maxillary premolar and molar region. A periodontal dressing was placed over the membranes and secured in the interproximal spaces. The dressing was removed after 10 days, and membrane integrity was evaluated by two examiners using a Likert-like grading scale (grades 1,5). Results: Eight subjects withdrew from the study due to discomfort, pain, or dislodging of the pack. Of the three membranes tested, RCL appeared to be the most resistant to degradation (median grade 5), compared with GCL (2.25) and NCL (1.75). Conclusions: Marked differences in membrane integrity were found between the three tested membranes after 10 days in the oral cavity. These differences may be part of the important factors determining the outcome of the regenerative treatment modality in cases of premature membrane exposure. To cite this article: Klinger A, Asad R, Shapira L, Zubery Y. In vivo degradation of collagen barrier membranes exposed to the oral cavity. Clin. Oral Impl. Res. 21, 2010; 873,876. doi: 10.1111/j.1600-0501.2010.01921.x [source] In vitro fracture behavior of maxillary premolars with metal crowns and several post-and-core systemsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2006Wietske A. Fokkinga The in vitro fracture behavior of severely damaged premolars, restored with metal crowns with limited ferrule and several post-and-core systems, was investigated. Crowns of maxillary premolars were removed and canals were prepared with Gates Glidden drills and with Parapost drills. Groups of 11 samples were each treated with cast post-and-cores (Parapost XP, Wironium Plus) (group 1), prefabricated metal posts (Parapost XH) (group 2), prefabricated glass fiber posts (Parapost FiberWhite) (group 3), and custom-made glass fiber posts (EverStick Post) (group 4). Posts and composite cores and metal crowns in groups 2, 3, and 4 were adhesively cemented. Post-and-cores and crowns in group 1 were cemented with phosphate cement. Thermocycling was performed (6,000×, 5,55 °C). Two static load tests (30°) were applied. During the first load test (preloading) no failures occurred. Failure modes from the second load test were categorized into favorable and unfavorable failures. Mean failure loads among the four groups (group 1, 1845 N; group 2, 1718 N; group 3, 1812 N; and group 4, 1514 N) were not significantly different. Unfavorable failures were root fractures and favorable failures were postcrown displacements. No differences in frequencies of unfavorable/favorable failures were seen among the groups. The results suggest that different post-and-core systems have no influence on the fracture behavior of severely damaged premolars restored with metal crowns with limited ferrule. [source] Influence of endodontic treatment, post insertion, and ceramic restoration on the fracture resistance of maxillary premolarsINTERNATIONAL ENDODONTIC JOURNAL, Issue 6 2010K. Bitter Bitter K, Meyer-Lueckel H, Fotiadis N, Blunck U, Neumann K, Kielbassa AM, Paris S. Influence of endodontic treatment, post insertion, and ceramic restoration on the fracture resistance of maxillary premolars. International Endodontic Journal, 43, 469,477, 2010. Abstract Aim, To investigate the effects of endodontic treatment, post placement and ceramic restoration type on the fracture resistance of premolars. Methodology, One hundred and twenty teeth maxillary premolars were allocated to four groups (A,D; n = 30). In group A, mesio-occlusal-distal-inlays with a buccal and palatal wall of 2 mm (MOD), in group B partial onlays with palatal cusp coverage and in group C total onlays with buccal and palatal cusp coverage were prepared. Group D served as untreated controls. Groups A,C were divided into three subgroups (n = 10): (i) teeth received solely the described preparations, (ii) teeth were root filled, (iii) teeth were root filled and quartz fibre posts were placed. Teeth were restored using Computer-assisted design/computer-assisted machining-ceramic-restorations and subjected to thermo-mechanical-loading; subsequently, the buccal cusp was loaded until fracture. Results, Group D revealed significantly higher fracture resistance [mean (standard deviation)] [738 (272) N] compared to all other groups (P < 0.05; post hoc test Dunnett). For groups A,C, fracture resistance was significantly affected by the restoration type (P = 0.043) and endodontic treatment/post placement (P = 0.039; 2-way anova). Group A [380 (146) N] showed significantly lower fracture resistance compared to group B [470 (158) N] (P = 0.048; post hoc test Tukey). Compared to non-endodontically treated teeth [487 (120) N], root filled teeth revealed significantly lower fracture resistance [389 (171) N] (P = 0.031). Conclusion, The restoration of cavities with a remaining wall thickness of 2 mm using ceramic MOD-inlays is inferior with respect to the fracture resistance compared to partial onlay restorations. Root filled teeth without post placement show lower fracture resistance compared to non-endodontically treated teeth. [source] Effects of adhesive systems and luting agents on bonding of fiber posts to root canal dentinJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2006Francesca Monticelli Abstract The study evaluated the influence of different luting materials on the microtensile bond strength of glass fiber posts to root canal dentin. Thirty extracted maxillary premolars were endodontically treated, and the roots were prepared for post cementation using the FRC Postec system (Vivadent). Two luting materials (Multilink, Vivadent and Clearfil Photo Core, Kuraray) were used in combination with three adhesive: Multilink Primer (Vivadent), Clearfil Photo Bond, and Clearfil New Bond (Kuraray). A composite build-up was performed around the root to provide adequate gripping during testing. Specimens were cut to obtain beams with the post in the center and with the radicular dentin overlaid by the composite build-up on each side. Microtensile testing was performed with a universal testing machine at a cross-head speed of 0.5 mm/min. The failure mode was classified under a stereomicroscope and four representative beams of each group were selected for SEM analysis. Bond strength data that were analyzed with two-way ANOVA and Student-Newman-Keuls multiple comparisons tests revealed that adhesive systems, luting materials, and the interaction between these two factors significantly influenced the bond strength results (p < 0.01). Multilink applied with its own adhesive system obtained the best results, while the lowest bond strength was achieved with clearfil photo core in combination with multilink primer. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Subcrestal placement of two-part implantsCLINICAL ORAL IMPLANTS RESEARCH, Issue 3 2009Maria Welander Abstract Objective: The aim of the present experiment was to study the healing around two-part implants that were placed in a subcrestal position. Material and methods: Five mongrel dogs, about 2 years old, were included. The mandibular premolars and the first, second and third maxillary premolars were extracted. Three months later two test and two control implants (OsseoSpeedÔ, 3.5 mm × 8 mm) were placed in one side of the mandible. The implants were placed in such a way that the implant margin was located 2 mm apical to the bone crest. In the test implants, the surface modification extended to the implant margin and, thus, included the shoulder part of the implant. Regular abutments with a turned surface (ZebraÔ) were connected to the control implants, while experimental abutments with a modified surface (TiOblastÔ) were connected to the test implants. A plaque control program that included cleaning of implants and teeth every second day was initiated. Four months later the dogs were euthanized and biopsies were obtained and prepared for histological analysis. Results: The marginal bone level at the test implants was identified in a more coronal position than that at the control implants. In 40% of the test implants, the bone-to-implant contact extended coronal of the abutment/fixture (A/F) border, i.e. in contact with the abutment part of the implant. The connective tissue portion of the peri-implant mucosa that was facing the test abutments contained a higher density of collagen and a smaller proportion of fibroblasts than that at the control sites. Conclusion: It is suggested that osseointegration may occur coronal to the A/F interface of two-part implants. Such a result, however, appears to depend on the surface characteristics of the implant components. [source] Time- and dose-dependent mitogenic effect of basic fibroblast growth factor combined with different bone graft materials: an in vitro studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2006Xanthippi E. Dereka Abstract Objectives: In periodontal regeneration, the growth factor concentrations and the delivery system used are of great importance. In an attempt to assess the mitogenic effect of basic fibroblast growth factor (bFGF) on periodontal ligament (PDL) cells combined with different bone replacement materials, two allografts of cortical (DFDBA) and cancellous (DFBA) bone and an anorganic bovine material with a synthetic peptide (ABM P-15) were used. The purpose of this study was to evaluate the in vitro mitogenic effect of different doses of bFGF alone or in combination with DFDBA, DFBA and ABM P-15 on human PDL cells in a time-dependent mode. Material and methods: PDL cell cultures were derived from the mid-root of four maxillary premolars. Cells were grown and reached confluence. On day 2 of quiescence, new medium was added along with (1) 1, 5, 10 and 25 ng/ml of bFGF alone, (2) 10 mg of DFDBA, DFBA and ABM P-15 alone and (3) their combination. The mitogenic effect was determined at 24 and 48 h of culture by using a hemocytometer chamber. The cells were counted under a phase contrast microscope. Results: The results revealed that bFGF at the highest concentrations and after 48 h exerted a significant mitogenic effect on PDL cells, and also DFDBA and DFBA supported cell proliferation. Furthermore, DFDBA and DFBA enriched with bFGF had a significant mitogenic effect after 48 h of culture. ABM P-15 with 10 and 25 ng/ml of bFGF up-regulated PDL cell proliferation after 48 h of incubation. Conclusions: The findings of this study demonstrate the beneficial role of bFGF combined with DFDBA and DFBA as carriers in periodontal repair. [source] | ||||||||||