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Biomedical subjects

P Pospiech

Publications and source records attributed to P Pospiech.

10 recordsLinked to original sources
PubMed2005

Effects of prosthetic treatment for shortened dental arches on oral health-related quality of life, self-reports of pain and jaw disability: results from the pilot-phase of a randomized multicentre trial.

A multi-centre randomized clinical trial is under way at 14 university dental schools in Germany to compare prosthodontic treatments for the shortened dental arch (SDA). One of the aims of this pilot-study was to measure the effect of two treatment options of the SDA on oral health-related quality of life and on the Research Diagnostic Criteria (RDC) for temporomandibular disorders (TMD). Thirty-four patients participated in the pilot-study. Inclusion criteria were: all molars were missing and the presence of at least both canines and one premolar in each quadrant. Participants were randomly assigned to receive either removable partial dentures including molar replacement (RPD_group) or retain a premolar occlusion (PROC_group). The Oral Health Impact Profile (OHIP-49) and the RDC for TMD were completed by participants before treatment (pre-treatment), 6 weeks (6 wks), 6 months (6m) and 12 months (12 m) after treatment. At the 12-month follow up, data of 10 women and 11 men (mean age: 62 +/- 10 years) were available. Medians of the OHIP total-scores were as follows: RPD (n = 10), 43.5 (pre-treatment), 18.2 (6 wks), 13.3 (6m), 14.7 (12 m). PROC (n = 11): 31.8 (pre-treatment), 27.1 (6 wks), 8.8 (6m), 8.3 (12 m). Significant differences were shown for RPD_group between pre-treatment and 6m/12 m and for PROC_group between pre-treatment and 6m. There were no significant differences between treatment groups at any time. Within each group, an improvement of life-quality was observed. No significant difference could be reported between the two therapy concepts. This may be due to the low sample size within the pilot study.

Aged↗
PubMed2000

Fracture resistance of posterior metal-free polymer crowns.

STATEMENT OF PROBLEM: Improved mechanical properties of contemporary composites has resulted in the extended use of composites for the restoration of posterior teeth. Although the indication of polymers was extended to metal-free individual crowns, the influence of tooth preparation design and cementation methods on the stability of these artificial crowns remains unknown. PURPOSE: This in vitro study evaluated the effect of axial tooth preparation design, occlusal dimension, and cementation technique on the fracture resistance of metal-free posterior Artglass crowns. MATERIAL AND METHODS: Seventy-two extracted human third molars, assigned to experimental groups by size, received standardized tooth preparation. Axial tooth preparation included an invasive approach with 1-mm deep shoulder and a less invasive 0.5-mm chamfer preparation, whereas occlusal reduction was either 0.5 mm or 1.3 mm. Artglass crowns that restored the original tooth contour were cemented with 3 cements: zinc phosphate cement (ZnP), glass ionomer cement (GIC), or a resinous cement in combination with a dentinal bonding agent. After 10,000 thermal cycles between 5 degrees C and 55 degrees C, artificial crowns were vertically loaded until compression to failure. Significant differences of fracture loads between experimental groups were assessed by paired Mann-Whitney U tests. RESULTS: Minimal fracture resistance for all combinations excluded 500 N. However, 9 of 24 Artglass crowns cemented with ZnP loosened after thermocycling. Adhesive cementation resulted in a significantly greater fracture resistance compared with GIC and ZnP (P=.02). Increased occlusal thickness (0.5 to 1.3 mm) resulted in greater stability, whereas a 1-mm deep shoulder tooth preparation did not improve durability compared with a 0.5-mm chamfer finishing line. CONCLUSION: A minimally invasive 0.5-mm axial chamfer tooth preparation combined with sufficient occlusal reduction and adhesive cementation recorded the greatest stability for posterior metal-free Artglass crowns.

Cementation↗
PubMed1996

Evaluation of diagnostic criteria from computerized axiography to detect internal derangements of the TMJ.

Objective of this study was to evaluate the diagnostic value of 3-D computed axiography to detect anterior disk displacements (ADD) of the TMJ. 65 patients with MRI confirmed ADD with reduction and 27 patients with ADD without reduction were examined by 3-D computed axiography. 44 healthy volunteers with normal disk position and joint function served as controls. A descriptive analysis of the axiographic opening/closing cycle revealed significantly higher rates of abrupt deviations, accelerations/decelerations, and crossings for ADD with reduction compared to healthy volunteers. A new axiographic index reduced the number of false positive to 10% and false negative to 14% of the diagnosis. ADD without reduction was characterized by significantly shorter opening curves. The optimum split point at 11 mm, resulted in 10% false positive and 20% false negative diagnosis. However, the diagnostic value of computed axiography was reduced by the significant influence of the clicking or limited joint on the contralateral TMJ.

Adolescent↗
PubMed1996

All-ceramic resin-bonded bridges. A 3-dimensional finite-element analysis study.

Resin-bonded fixed partial dentures (FPD) with a metal framework have some disadvantages: a grey shimmer of the metal wings through the abutment teeth, a higher corrosion rate, and an allergenic potential of the non-precious alloys used. The Al2O3 ceramic In-Ceram seems to be strong enough to serve as a framework for resinbonded all-ceramic FPDs. Because of the fact that ceramic wings often don't have enough inter-occlusal space, a new preparation design was developed. The objective of this study was to determine the influence of load orientation (45 degrees and 60 degrees) and the design of the interproximal connector on the stress distribution in the bridges. A 3-dimensional finite-element model was developed to simulate the anatomical situation. The biting force was assumed as 250 N and oriented in oro-buccal direction. The loading-point was palatal 1.5 mm beneath the incisal edge. It was found that stress generally increased with an angle of the biting force of 60 degrees. A small interdental connector (3 mm height) and/or strong interdental separation resulted in stresses of up to 455 MPa (45 degrees) or 534 MPa (60 degrees). Less separation with rounded edges and a higher connector (4 mm) reduced the stress to 122 MPa (45 degrees) and 143 MPa (60 degrees). Due to an average tensile strength of In-Ceram at 340-400 MPa, an all-ceramic resin-bonded FPD may only be recommended if the height of the connector could be minimum 4 mm. Rounded edges and little interdental separation are significant for stress reduction.

Allergens↗
PubMed1996

A new design for all-ceramic resin-bonded fixed partial dentures.

After 7 years of clinical experience, the alumina ceramic, In-Ceram, can be regarded as a well-proven material for all-ceramic crowns. Because of its high strength, this material can also be used for small all-ceramic fixed partial dentures. First attempts at using this material for resin-bonded prostheses revealed a high failure rate. The aim of this article is to present a new preparation design for all-ceramic resin-bonded fixed partial dentures that allows fabrication of highly esthetic and also tooth-saving adhesive prostheses. Clinical results over a period of 4 years revealed that they are strong enough to replace anterior teeth. Nevertheless, positive long-term clinical results are necessary before a general recommendation can be given for this kind of prosthesis.

Aluminum Oxide↗
PubMed1993

Clinical factors affecting adhesive fixed partial dentures: a 6-year study.

One hundred forty-one adhesive fixed partial dentures were placed under controlled conditions for a 6-year longitudinal study. The influence of location (anterior/posterior, maxilla/mandible), tooth preparation techniques (retentive/less invasive), and four different methods of metal conditioning (sandblasting/electrolytic etching and/or pyrolytic/tribochemical silane coating) on the survival rate was investigated. Failures (23 of 24) were caused by loss of adhesion at the metal-cement interface. The retentive tooth preparation reduced the risk of failure to almost one twentieth, but the intraoral location did not influence survival time. The effect of silane-coating on longevity was extremely positive and was not reflected by successful retainers.

Chi-Square Distribution↗
PubMed1991

[Clinical comparison of bonded bridges as a function of preparation and metal conditioning. Statistical analysis of failures].

A total of 107 bonded bridges could be re-evaluated after a mean period of 2.3 years and a maximum of 5 years. The preparation of mechanical retentive aids, such as grooves and bores resulted in a significant reduction of failure rates after one year. Electrolytical etching or silicoating of the CoCr restorations failed to have any effect on the failure rates of those bridges that were provided with adequate mechanical retention.

Adolescent↗
PubMed1991

[Success of implantation depending on the type of prosthetic superstructure].

53 patients with 120 endosseous implants could be re-evaluated after a mean period of 2.7 years (maximum 5 years). Using casts from the upper with transfer posts and lower jaw, we measured the deviation of the implant axes from their ideal direction and localisation. Furthermore, we tried to find out, whether an unfavourable localisation compromised the prognosis of osseointegrated implants. Ideal, axial load by the prosthetic construction was often impossible because of unfavourable localisation of the implants. In a rank correlation analysis we found a significant influence of unfavourable localisation on prognosis in the group of hinge bars. Further weak correlations were revealed between loss of attachment and gingiva index which in turn was correlated with the plaque index.

Adolescent↗
PubMed1989

[Occlusal surfaces of glass-ceramic (Dicor) and VMK-crowns compared by electron scanning microscopy].

The surface of painted and unpainted glass ceramic-crowns (DICOR) was compared with that of ceramometallic-crowns by the means of the Scanning Electron Microscope (SEM). If handled correctly and accurately glass ceramic presents a superiorly surface-quality. A disadvantage is the great thickness of the paint, that forces to make a compromise in the occlusal region: here we should prefer the advantage of the possibility to make a correct occlusal relation to the antagonist tooth with wax-pattern to a homogenous smooth surface. Ceramometallic crowns should get a real glazing finish and we have to set value on a correct modelation of the frame and an optimal veneer at the crown margin.

Ceramics↗