Biomedical subjects

I Nergiz

Publications and source records attributed to I Nergiz.

At least 19 recordsLinked to original sources

PubMed2006

Yield strength of zirconia and glass fibre-reinforced posts.

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.

Dental Materials↗

PubMed2006

Bending resistance of unit cast posts-and-cores compared with noble posts following molten cast core attachment.

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.

Dental Alloys↗

PubMed2005

Effect of luting agents and reconstruction techniques on the fracture resistance of pre-fabricated post systems.

Fracture resistance and fracture modes of endodontically treated maxillary central incisors restored with different post-and-core systems covered with all-ceramic copings were evaluated. Ten samples were prepared for each group. Groups 1, 2 and 3 consisted of tooth-coloured post-and-core, zirconia post (Cosmopost) with a composite core (Tetric Ceram), zirconia post (Cosmopost) with a custom made ceramic core (Cosmo Ingot), glass fibre-reinforced post (FRC Postec) with a composite core (Tetric Ceram), respectively. Group 4 consisted of a titanium post (ERpost) with a composite core (Tetric Ceram). The control group (group 5) consisted of root-filled incisors without posts. Tooth-coloured posts were cemented in the roots using Variolink-2, while titanium posts were cemented in the roots using Harvard cement. The all-ceramic copings were cemented using Variolink-2. Static load was applied to 2 mm below the incisal edge on the palatinal surface of each sample until they were fractured. Fracture data were obtained and statistically analysed with One-way anova and a Tukey's test. The results of the means and standard deviations of the fracture resistance during static loading were: 497.5 +/- 61.94 (1), 474.61 +/- 96.84 (2), 494.61 +/- 104.67 (3), 581.34 +/- 105.36 (4), 420.42 +/- 127.48 (5). There were statistically significant differences between groups 4 and 5. Glass fibre-reinforced posts and composite cores (group 3) showed the most catastrophic failure. Consequently, zirconia ceramic posts can be used in clinical practice.

Analysis of Variance↗

PubMed2004

Various conditioning methods for root canals influencing the tensile strength of titanium posts.

Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, manufacturers' instructions for this purpose differ widely from one another. The aim of this study was to compare the tensile bond strengths of passive, tapered, titanium root posts that were luted with four different resin composite cements (Compolute Aplicap, Flexi-Flow cem, Panavia 21 EX, Twinlook) in the root canals at three conditions, namely (i) no conditioning, (ii) etching with 37% phosphoric acid, and (iii) etching + bonding agent application. Panavia 21 EX was further tested after using the primer for the post-surface according to the manufacturer's recommendations. The posts luted with zinc phosphate cement (Tenet) acted as the control group. Following endodontic preparation of 140 intact anterior teeth with hand instruments, the post-spaces were prepared using the opening drills of the corresponding size of the posts. The samples were first stored in water at 37 degrees C for 24 h and then thermocycled (5000 cycles, 5-55 degrees C, 30 s). The tensile strength values were measured with the universal testing machine at a crosshead speed of 0.5 mm min(-1). The data were analysed statistically using anova and corrected with Scheffé test due to the significance levels (P < 0.05). The tensile bond strengths of the titanium posts after luting with various cements and thermocycling were affected by the conditioning systems used for the root canals. Tensile bond strengths were the highest with Flexi-Flow (475 +/- 78 N) followed in descending order by Panavia 21 EX (442 +/- 97 N), Twinlook (430 +/- 78 N) and Compolute Aplicap (352 +/- 76 N) after conditioning the root canal. The use of primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia 21 EX group (375 +/- 77 N) (P < 0.001). Tensile bond strengths obtained after luting the posts with zinc phosphate cement (414 +/- 102 N) were not significantly different (P < 0.05) than those of resin composite cements. Although the importance of conditioning the root canal was evident for Panavia 21 EX, it was not the case for the other luting cements tested.

Acid Etching, Dental↗

PubMed2002

Effect of length and diameter of tapered posts on the retention.

The force transmission of tapered unthreaded posts along the root has been reported to be homogenous but their retentive strength was found to be lower compared with those of parallel unthreaded or other kinds of threaded posts. The purpose of this in vitro study was to investigate the effect of length and diameter on the retentive strength of sandblasted tapered prefabricated titanium posts (Erlangen post system). Posts with constant taper angle but with three different lengths (9, 12, 15 mm) and apical diameters (0.5, 0.9, 1.1 mm) were cemented using zinc phosphate cement into the prepared and roughened post spaces of 90 intact anterior teeth. The post retention concerning length and diameter, being independent from each other, was measured by a tensile force test. The retentive strength was found to be proportional to the length as well as to the diameter of the posts. The mean minimum strength (181 +/- 14 N) recorded for the thinnest and shortest post was significantly lower than that of mean maximum strength (612 +/- 85 N) obtained from those of the thickest and longest post. Proportional bond strengths of the posts comprising their surface areas ranged between 6.8 and 7.9 N mm(-2) which were not significantly different between any group. The retention was effected strongly with the increase in the length (approximately 100%) than with the increase in the diameter (approximately 60%). Concerning the posts tested in this study, it is concluded that some caution should be exercised in the choice of post with appropriate length rather than diameter for the tooth concerned.

Cementation↗

PubMed2002

Bond strengths of five tapered root posts regarding the post surface.

The advantage of tapered passive root posts is their homogenous force transmission without creating stress peaks on the root surface because of their anatomical root form. However, their expected retentive strengths are low compared with the other post systems. The objective of this in vitro study was to determine the retentive strengths of five tapered post systems from different manufacturers using tensile tests. For this purpose, all posts were cemented with zinc phosphate cement (Tenet) into the roots of 50 intact anterior teeth according to the manufacturer's instructions for each system. The contact surface area between the root canal wall and the post was taken into account in the calculations in order to obtain comparable results for different post configurations. The highest bond strength values were achieved for the Erlangen post system (10.8 N mm(-2)) and MP Pirec post system (10 N mm(-2)). These values were more than three times those of the Velva-Post (3.2 N mm(-2)) and the Cylindro-Conical system (3.5 N mm(-2)) and five times more than those of the Dr Mooser post system (1.7 N mm(-2)). The bond strength values of the Erlangen post system, Cylindro-Conical system and Dr Mooser post system showed statistically significant differences compared with the other groups. The results of this study indicated that the bond strengths of tapered posts were not only affected by the contact surface but also by the taper angle, shape of the post system, the width of the cement joint, surface roughness of the posts as well as the form of the canal wall. In clinical practice, in case of choosing tapered posts with similar shapes, retention may still vary because of other factors.

Dental Bonding↗

PubMed2000

A case of localized ridge augmentation from using a titanium membrane: a pilot study.

The aim of this investigation was to histologically compare the effects of new titanium membranes with those of proven expanded polytetrafluoroethylene (ePTFE) membranes on alveolar ridge augmentation. The study was carried out using a canine mandible where the right and left premolar teeth were previously extracted. At the second month of healing following extraction, a total of seven similar defects were created on both sides of the mandible. Three defects received the titanium membrane, one of which was in the right side of the mandible. Two defects, one on each side, received the ePTFE membrane. The remaining two defects, both on the right side, served as control. Fixation and stabilization of the membranes were accomplished by using the Frios Augmentation System. After three months of healing, the animal was sacrificed, block sections were taken and processed for histological examination according to the cutting and grinding technique. The results revealed that the ePTFE and titanium-treated defects, and the controls, showed complete bone fill with the exception that there was a more pronounced and thicker connective tissue formation in titanium-treated sites as compared to the ePTFE treated and control sites.

Alveolar Ridge Augmentation↗

PubMed2000

Effects of different exposure values on diagnostic accuracy of digital images.

OBJECTIVE: The aim of this in vitro study was to compare the effects of different exposure values on the image clarity of 3 digital radiographic systems and 1 conventional direct-exposure emulsion x-ray film. METHOD AND MATERIALS: Three digital radiographic systems, Digora, RVG, and Sidexis, were compared with the conventional dental x-ray film, Ektaspeed Plus. A medullary bone fragment and human teeth were radiographed with varying voltage, exposure time, and focus-receptor distance. Clinical criteria to evaluate image clarity were detail resolution, sharpness, contrast resolution, and artifacts of the different tooth and jaw structures. RESULTS: The optimal exposure times for digital imaging varied between 0.02 and 0.13 seconds and depended on the objects and the imaging systems. Optimal resolution was obtained when a voltage of 60 kV was used. The focus-receptor distance of 33 to 40 cm resulted in the best contrast and sharpness. Digital images did not always provide the detail resolution or sharpness achieved by conventional radiographs. CONCLUSION: The recommended exposure time for digital images amounted to approximately half the time needed for conventional film. Digital images had to be modified by adjusting the contrast and brightness to optimize the visibility of the areas to be diagnosed.

Artifacts↗

PubMed1999

Comparison between manual and mechanical methods of interproximal hygiene.

OBJECTIVE: The aim of this study was to compare the effectiveness of the automated Interclean Interdental Plaque Remover with that of interdental brushes and Ultrafloss. METHOD AND MATERIALS: The interdental hygiene effectiveness of 35 healthy patients suffering from gingivitis was studied by an examiner daily over a period of 1 week. The sizes of the interdental spaces were classified and corresponding-sized interdental brushes or floss was selected. In a random, split-mouth design both interdental cleaning methods, mechanical and manual, were applied while the patients continued to use standard brushing techniques. Disclosed proximal plaque, the papillary bleeding index, and interdental bleeding tendency on stimulation were evaluated. RESULTS: The papillary bleeding index was reduced from an average value of 40% to 25%. Only 5% of interproximal plaque remained after manual interdental cleaning, whereas 40% of plaque was still present after use of the Interclean device. Cleaning efficiency of manual and mechanical methods was comparable in only 1 interproximal space size. At the end of the study, the interdental bleeding on stimulation was significantly higher in the automatically cleaned interspaces than in the manually cleaned spaces. CONCLUSION: Manual interproximal cleaning was more effective than the automated device.

Adult↗

PubMed1998

Reactions of peri-implant tissues to continuous loading of osseointegrated implants.

Functional and morphologic reactions of peri-implant bone surrounding screw implants (Bonefit) were studied in three dogs by loading the implants with continuous forces of 2 (about 204 gm) and 5 N (about 510 gm). Eight implants were inserted to an endosseous length of 12 mm and placed about 10 mm apart in the region of the lower premolars. The fixtures healed in a closed environment for 12 weeks, after which they were uncovered and loaded with abutments and orthodontic devices to produce horizontal distraction with a force of 2 N (about 204 gm) for 12 weeks. Subsequently they were loaded with 5 N (about 510 gm) for another 24 weeks. The distance between and the mobility of the implants were determined before and after each phase of experimental loading. Fixtures of the same type that were osseointegrated and not exposed, or osseointegrated and loaded by mastication, were used as a control. Animals were euthanized and specimens sectioned. The result was that continuously loaded implants showed no significant displacement for any force level. The mobility of the fixtures increased slightly by about 1 Periotest-value (PTV) at the end of the experiment. No significant peri-implant pocket could be seen in implants loaded by continuous or masticatory forces. Histologic and morphometric evaluation indicated compaction of bone as a result of loading. Osseointegrated implants have potential as a firm osseous anchorage for orthodontic treatment and can resist continuous horizontal forces of at least 5 N (about 510 gm) during a period of several months.

Absorptiometry, Photon↗

PubMed1998

A brief history and current status of metal-and ceramic surface-conditioning concepts for resin bonding in dentistry.

The bond strength of resin to metal or ceramic surfaces has been increased with the introduction of various surface-conditioning techniques. The principles of currently used conditioning methods and clinical trials with these methods are summarized. The advances in surface-conditioning methods have increased bonding to a high level; however, interpretation of the literature review indicates that chemical bonding by means of recently introduced techniques provides better results than does mechanical bonding.

Aluminum Oxide↗

PubMed1997

Interdisciplinary concepts in treating adult patients.

Pre-prosthetics, as a part of orthodontic treatment in adults has gained increasing importance during recent years. Through coordinated orthodontic, prosthetic and periodontal treatment plans, patients with partial dentition can be offered further treatment possibilities. Such planning would allow for fixed prosthetic treatment possibilities and the survival of critical teeth. They would provide for better aesthetics and avoid functional disturbances. The aim of the present study was to present reports of patients treated by coordinated work at the Dental School of Hamburg University. In patients with partial dentition, premolars were uprighted and distally moved and molars were extruded to be used as abutments for fixed prosthetic reconstructions. Following trauma, the position of the remaining anterior teeth was improved to provide for optimal aesthetics after prosthetic treatment. Extraction of a subalveolarly fractured tooth is avoided through root extrusion and post-core reconstruction. The results demonstrate the advantages of pre-prosthetic treatment as regards stability, aesthetics and function. With the help of pre-prosthetic orthodontic treatment, complicated treatment situations could be handled more successfully than would have been the case without such treatment.

Adolescent↗

PubMed1997

Effect of different surface textures on retentive strength of tapered posts.

STATEMENT OF PROBLEM: Tapered posts allow for the preservation of tooth substance in the fragile apical area and are advantageous in clinical situations where they conform to the root and canal configuration of endodontically treated teeth. However, their lower retention compared with passive parallel-sided or active threaded posts is a disadvantage. PURPOSE: This study determined the retentive strength of tapered titanium posts with different surface textures and examined the effect of roughening dentinal walls of the prepared post space. MATERIAL AND METHODS: Posts with four surface configurations (smooth, with and without grooves, and sandblasted, with and without grooves) were examined when cemented in extracted anterior teeth. RESULTS: The smooth post showed the lowest retentive strength. Sandblasting the smooth post more than doubled its retentive strength. The retentive strength of both smooth and sandblasted posts could be further increased by the addition of circumferential grooves. Roughening the dentinal walls of the prepared post space increased the retentive strength of sandblasted posts with and without grooves even more. CONCLUSIONS: These findings indicated that, when a tapered post is used, roughening the dentin canal wall, as well as sandblasting and grooving the post, can provide statistically significant additional resistance to dislodgment.

Analysis of Variance↗

PubMed1996

Shear bond strength of a new polycarbonate bracket--an in vitro study with 14 adhesives.

Shear bond strength and failure location were used to evaluate the effectiveness of plastic bracket primers for bonding diacrylate adhesives on a new fibre-reinforced polycarbonate bracket. Maxillary incisor polycarbonate and mesh-based brackets as control were bonded to human incisors with 14 different adhesives (four filled diacrylate two-paste, six diacrylate one-step and four power-liquid acrylic adhesives), and after thermo-cycling for 2000 cycles between 5 degrees and 55 degrees C, tested in shear. A non-parametric test (Mann-Whitney U test) was used to compare the shear bond strength of the polycarbonate brackets with the mesh based brackets and a One-way test (according to Scheffe) to compare the shear bond strength of different adhesives. The following conclusions can be made: 1. Seven of the 14 adhesives used in this study with both types of brackets demonstrated adequate shear bond strength values for the clinical application. The exceptions were: Achieve Mix, No-Mix:30 Silkon, Lee Insta-Bond, Ortho-Loc and Bond-Eze, all with too low a shear bond strength for one or both types of brackets, and finally Quasar, which used with the plastic brackets sometimes caused enamel fractures, due to high bond strength. 2. The adhesives with their own plastic primer demonstrated higher blood strength values than those without plastic primer, and two-paste adhesives used with plastic primer displayed a higher bond strength than the other adhesives. 3. Generally, the shear bond strength values of the one-step adhesives were lower compared with the two-paste adhesives. 4. The liquid-powder adhesives demonstrated very different values for bond strength.

Composite Resins↗

PubMed1995

[The shearing strength of titanium brackets depending on the coating procedure].

It has long been recognized that corrosion of the metal alloys used in the different fields of dentistry can cause intra-oral problems such as allergic reactions. Titanium, a metal all but impervious to corrosion, presents an alternative to the metal alloys used in the fabrication of orthodontic brackets. The purpose of this study was to test the bonding strength between titanium brackets treated with 5 different opaque and non-opaque coatings and a 2-phase adhesive. Five coating methods were tested: N1 (Dentaurum), N2 (Dentaurum), Rocatec (Espe), Sebond (Schütze), Silicoater Standard (Kulzer). After bonding the brackets with a mix adhesive, they were thermocycled and then the shear bonding strength established. Silicoated titanium bracket bases showed clinically acceptable bonding values with the exception of those coated with Sebond without opaquer layer. While the silicoating methods N1, N2, and Rocatec demonstrated minimum bonding strength using the opaquer Visio-Gem, the bonding strength of the bracket bases coated with Sebond MKV, Silicoater Standard and the opaquer appropriate to each was significant increased. Among all the coated surfaces, methods N1, N2, and Rocatec appear to establish the optimum bonding strength values. In addition, the thin opaquer layer (Visio-Gem) used together with these methods offers a good surface adaptation of the bracket to the tooth surface.

Dental Bonding↗

PubMed1993

[The bonding strength of silane-coated metal brackets with different adhesives].

The aim of this study was to test under thermo stress the effect of various adhesives on the bonding strength of brackets with a new retention mechanism in comparison to brackets with a conventional retentive basis. In the test 17 different adhesives and metal brackets with two different retention mechanisms were used. One group of metal brackets was coated by means of the Kulzer silane coating procedure and the other had a mesh basis. The latter served as the control group. Both were held in place by adhesives and their bonding strength tested. The following conclusions were drawn: 1. Both of the bracket types demonstrated the highest bonding strength with the mixed composites (paste/paste). 2. The silane coated bracket bases demonstrated altogether higher bonding strength than the mesh brackets, but the difference with the light-cured and the epoxy-adhesives was only statistically significant.

Dental Bonding↗

PubMed1992

[The effect of the different metal components on bracket adhesive strength in the Silicoater procedure].

This study was undertaken to test the theory that different kind of metal alloys can influence the bond strength of the silane treated bracket bases. Seven different types of brackets, each with different metal properties, were tested. 20 brackets of each type were used, half of them were silanated with a special Silicoater treatment. The following conclusions can be made: 1. The silane coated plain bracket demonstrated a higher bond strength than all the tested untreated brackets; 2. the brackets of the company Dentaurum demonstrated a statistically significant higher bond strength than the brackets of all the other companies.

Dental Alloys↗

PubMed1991

[Bonding strength of brackets with and without silane coating].

This study was undertaken to show that a silane treated bracket base can provide a better bonding to the enamel than conventional bonding bases commercially available. Five different types of metal brackets, each with different retentive properties, were tested. 20 brackets of each type were used, half of them silanated with a special silicoater treatment. The brackets were bonded to the surface of the teeth with Concise Enamel Bond and were then tested to failure in an Instron testing machine after 28 days. The following conclusions can be drawn from the study: 1. Silane-coated bracket bases demonstrated a higher bonding strength than the conventional bases, 2. silane treatment of plain bases is an effective method for the bonding of brackets to teeth, similiar to non-silane-boated brackets with additional mechanical retentive devices.

Acrylic Resins↗