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Biomedical subjects

P Ottl

Publications and source records attributed to P Ottl.

9 recordsLinked to original sources
PubMed2002

Fracture characteristics of carbon fibre, ceramic and non-palladium endodontic post systems at monotonously increasing loads.

A carbon fibre post system, three non-palladium and one palladium metal post systems, two ceramic post systems, and a metal post system with a ceramic core were studied in vitro. The control group consisted of root-filled test teeth without posts. The test teeth were identical artificial roots of an upper central incisor made from a posterior composite whose module of elasticity was similar to that of natural dentine. All posts were cemented in the roots using Panavia 21 TC. Subsequently, standardized full crowns were cemented onto all roots. On a universal testing machine, the test teeth were loaded palatally at monotonously increasing loads until root fracture. The highest mean fracture loads were found for the carbon fibre post system (312.5 +/- 58.8 N). The fracture load of non-palladium metal posts (242.3-300.4 N) did not differ significantly from that of the Perma-dor post (265.9 N), which does contain palladium. Values of 300.3 +/- 89.3 N (aluminium oxide ceramics) and 193.5 +/-57.0 N (zirconia ceramics) were found for the ceramic posts. The control group exhibited a fracture load of 228.8 +/- 35.7 N. The mean distance between the vestibular end of the fracture gap and the point of force application was between 10.1 +/- 2.3 and 14.7 +/- 1.2 mm.

Carbon↗
PubMed2001

Laboratory strength of glass ionomer and zinc phosphate cements.

PURPOSE: The present in vitro study examined 3 mechanical properties, namely compressive, flexural, and diametral tensile strength, of various commercially available cements and core materials as a function of time after mixing. MATERIALS AND METHODS: The examined materials were 2 cermet cements (Ketac Silver [ESPE, Seefeld, Germany] and Chelon Silver [ESPE]), 1 metal-reinforced glass ionomer cement (Miracle Mix [GC Dental Industrial Corp, Tokyo, Japan]), 2 conventional glass ionomer cements (Ketac Bond [ESPE] and Ketac Cem [ESPE]), 1 standard cure zinc phosphate cement (Harvard Cement [Richter and Hoffmann, Berlin, Germany]), and 1 zinc phosphate cement with the addition of 30% silver amalgam alloy powder (Harvard Cement 70% with Dispersalloy 30% [Richter and Hoffmann/Johnson and Johnson, East Windsor, NJ]). Properties were measured using a universal testing machine at 15 minutes, 1 hour, and 24 hours after first mixing. RESULTS: Compressive strengths varied widely between the 3 times of measurement from 5.8 +/- 6.6 MPa for Ketac Cem to 144.3 +/- 10.2 MPa for Ketac Silver. Twenty-four hours after mixing, the Bonferroni test showed significant (p <or= .01) differences between Ketac Silver and all other materials tested. Diametral tensile strengths ranged widely from 4.4 +/- 0.9 MPa for Ketac Cem to 11.5 +/- 2.2 MPa for Chelon Silver. At 15 minutes, 1 hour, and 24 hours after first mixing, the analysis of variance did not show any significant differences between Ketac Silver, Chelon Silver, and Miracle Mix. The 3-point flexural strength of Ketac Silver showed, at 15 minutes with 13.5 +/- 3.9 MPa and at 24 hours with 27.2 +/- 7.4 MPa, the highest values. CONCLUSIONS: Setting time influences the mechanical properties of the materials tested in this study. Ketac Silver, a glass ionomer cement reinforced with sintered glass-silver particles, showed the highest mechanical properties of the examined materials.

Analysis of Variance↗
PubMed2000

Organotypic cultures of gingival cells: an epithelial model to assess putative local effects of orthodontic plate and occlusal splint materials under more tissue-like conditions.

This article explores whether organotypic cultures of immortalized gingival keratinocytes constitute a suitable model for assessing the epithelial cell compatibility of two groups of dental resins, each of them representing one group used in orthodontics and temporo-mandibular disorders (TMD) therapy under conditions more closely resembling the actual tissue situation. The resins were tested with the agar diffusion assay (ADA) in conventional monolayer and organotypic cultures. Compared to the control exhibiting a neutral red destaining index of 3, the index of 4 obtained after exposure of monolayers to one soft permanent resin (Durabase) indicated the presence of a non-lytic but physiologically active substance. In contrast, the adaptation of the ADA to organotypic cultures revealed no apparent lesions at the epithelial surface by performing scanning electron microscopy, while histoarchitecture indicated the development of stratified surface epithelia. This was substantiated by undamaged cells in the uppermost cell layers and by the preservation of cell-to-cell contacts. Furthermore, indirect immunofluorescence for Ki-67 and the cytokeratins ck 14 and ck4 revealed that cell proliferation and epithelial structure were maintained, while differentiation was enhanced, possibly increasing epithelial resistance. The results obtained from the organotypic cultures suggest that (i) cell-affecting effects of materials visible in monolayer cultures may not be seen in epithelia resembling that in vivo and that (ii) enhanced differentiation may be associated with increased stability of the epithelial cells. Thus, organotypic cultures of gingival cells constitute a tissue model allowing short-term tissue compatibility studies of dental materials and rendering a potential candidate also for long-term studies.

Acrylic Resins↗
PubMed2000

The Procera AllCeram system.

The Procera AllCeram system is indicated for manufacturing all-ceramic crowns for single-tooth restorations in the anterior and posterior regions. In addition, it is possible to create metal-free superstructures on CeraOne abutments from the Brånemark implant system or crowns on individually prepared aluminum oxide abutments (CerAdapt). The Procera copings, which are manufactured using computer-aided design/manufacturing technology, are characterized by very good mechanical properties. Ceramic veneers tailored to the copings offer excellent esthetics, favorable abrasion behavior, and an ideal surface structure for non-inflammatory apposition of the periodontal or periimplant tissues. The present article offers an overview of previous scientific studies, describes clinical and laboratory procedures, and presents case reports.

Aluminum Oxide↗
PubMed1998

Temperature response in the pulpal chamber during ultrahigh-speed tooth preparation with diamond burs of different grit.

STATEMENT OF PROBLEM: Ultrahigh-speed tooth preparation can traumatize the hard dental tissues and the dental pulp. PURPOSE: This in vitro study examined the relationship between different grits of diamond burs on the temperature response within a pulpal chamber during tooth preparation with a turbine. MATERIAL AND METHODS: Newly extracted, undamaged third molars were secured by a rapid-tensioning device mounted on an air-supported slide. NiCrNi thermocouples were inserted apically and used to determine the temperature within a pulpal chamber. The grinding tests used cylindrical fine, coarse, and ultracoarse diamond burs. RESULTS: The maximal temperature elevation within the pulp was 3.2 degrees C, and the most pronounced rise in temperature occurred with ultracoarse burs. Temperature increases in the pulpal chambers and grinding times or temperatures of the cooling water were approximately proportional. Residual dentinal thickness was inversely proportional to temperature elevation within the pulpal chamber. CONCLUSIONS: This study demonstrated that coarse diamond burs resulted in more pronounced temperature increases within the pulpal chamber during tooth preparation. In addition, the benefit of short intervals between grinding steps and a cooling water temperature between 30 degrees C and 32 degrees C was confirmed. A cooling temperature of 38 degrees C to 43 degrees C did not afford actual cooling.

Body Temperature Regulation↗
PubMed1998

Success rates for two different types of post-and-cores.

The objective of our follow-up study was to evaluate the success of two different types of partially prefabricated post-and-core systems following crown placement. Two hundred and thirty-seven Permador posts and 49 Radix posts were evaluated clinically. Radiological follow-up was performed for 230 Permador posts and 47 Radix posts. The restorations had been in situ for an average of 3.9 years (Permador posts) and 2.3 years (Radix posts), respectively. Root canal fillings were evaluated as to their length, their homogeneity and their flushness with the walls of the root canal. The post-and-cores were evaluated for their orientation in the root canal and for the length of the inserted post relative to the length of the root. The position of the post was classified as centric in 78.0% of the restorations followed, and eccentric in 19.5%, while 2.5% showed a root perforation. The minimal requirement that the length of the post-and-core should at least be equal to the length of the clinical crown was met in 85% of the cases. Eighteen (6.3%) of the 286 teeth examined had to be extracted. There were significant correlations between insertion periods, horizontal bone loss, length of the root canal filling, and position of the post on one hand and tooth loss on the other.

Adult↗