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Results for “Prosthesis Retention”

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At least 1,207 records · Page 67Linked to original sources
PubMed1992

A 3-year clinical study of Astra dental implants in the treatment of edentulous mandibles.

A prospective study for the treatment of mandibular edentulism using the new Astra dental implant system was conducted on 54 patients. The clinical performance of 310 implants was monitored over 3 years. The survival rate was 100% for the prostheses and 98.1% for individual implants. Four implants failed during the first 3 months after placement, one was retained as a "sleeper," and two more were removed because of persistent discomfort. Both resorption and deposition of mandibular marginal bone were observed. Bone changes from baseline to the end of the first year ranged from -0.4 to +1.0 mm (median 0.00), from the first to the third year from -0.8 to +0.6 mm (median 0.04), and over the 3 years ranged from -1.1 to +1.0 mm (median 0.01). No marked mean bone resorption was observed during the first year compared to the two following years. A significant gain in marginal bone level was recorded in males, but in females the level was unchanged. There were no serious inflammatory reactions in the surrounding soft tissues during the 3-year follow-up period.

Adult↗
PubMed1992

Loads and designs of screw joints for single crowns supported by osseointegrated implants.

The problem of screw stability was approached in this study by calculating the maximum occlusal forces in vivo for patients with single implant restorations (which use only one screw to secure the prosthetic reconstruction to the implant). The measurements of occlusal forces together with geometric parameters for the individual patients were used to determine the necessary holding capabilities of the screw joint. Different screw designs were tried in bench test situations and the results were compared with clinical situations. A gold alloy screw with a flat head and high tightening torque (35 Ncm) produced the best results.

Bite Force↗
PubMed1992

Achieving ideal esthetics in osseointegrated prostheses. Part II. The single unit.

There are several advantages to the CeraOne single-tooth abutment. It seats directly onto the fixture, forming a nonrotating joint. A new type of gold alloy screw that can be tightened to 32 N/cm is used. In addition, the restoration is constructed on a prefabricated ceramic cap onto which porcelain is directly baked. A case report illustrates the technique and the highly esthetic results of such single-tooth replacement.

Adolescent↗
PubMed1992

Comparison of stress transmission in the IMZ implant system with polyoxymethylene or titanium intramobile element: a finite element stress analysis.

Using the finite element method, this study modeled a 4.0 x 13.0-mm IMZ implant, restored with a cast gold crown, to examine the influence of the polyoxymethylene (POM) intramobile element (IME) on the transmission of vertical and oblique forces. Stress concentrations in the bone and in components of the implant system were much greater under a 30-degree load than under an equal vertical load. Stress transmission to bone occurred chiefly in the crestal region, and these stresses were not reduced when the IME was modeled in POM rather than in titanium. Maximum stress concentrations occurred in the fastening screw.

Alveolar Process↗
PubMed1992

To vent or not to vent?

The complete seating of full coronal restorations during cementation is hindered by the inability of cement to flow from the internal surface of the crown, and possible binding of the crown on the tooth. Perforation venting is an effective technique to allow full seating but requires repair of the perforation. Provision of space between the crown and the tooth for cement flow is also an effective technique, and does not require repair of a perforation. Such spacing is commonly achieved with die spacer, and has the added possibility of decreasing crown deformation during cementation by diminishing binding between the crown and the tooth. A disclosing agent is effective in aiding complete seating by identifying areas of binding. These areas can subsequently be adjusted, which will allow more complete seating. The placement of an appropriate amount of cement in the crown or on the preparation is an important addition to cementation technique.

Cementation↗
PubMed1992

Fixture placement posterior to the mental foramen with transpositioning of the inferior alveolar nerve.

The results of 10 fixture placement operations with transpositioning of the inferior alveolar nerve are presented. Nerve transpositioning increased the operating time, but with experience this time should be reduced. Neurosensory dysfunction of the inferior alveolar nerve was found in 7 of 10 operated sites 1 week after surgery. Six months postoperatively, altered sensation was still present in 2 patients. Nerve function was normal in all patients 1 year postoperatively. The stability of fixtures was satisfactory throughout the examination period and the procedure should prove useful in treatment of the resorbed mandible posterior to the mental foramina.

Alveolar Bone Loss↗
PubMed1992

Clinical parameters of evaluation during implant maintenance.

This paper reviews investigations concerning the clinical parameters of evaluating dental implants during the maintenance phase of therapy. Clinical parameters that are discussed include mobility, gingival alterations, tissue movement, probing and attachment level measurements, bleeding upon probing, occlusion, and microbial monitoring. The role of implant radiology is discussed and encompasses radiographic interpretation, interval, and technique.

Alveolar Bone Loss↗
PubMedDate not supplied

Resonance frequency measurement of implant stability in vivo on implants with a sandblasted and acid-etched surface.

PURPOSE: To determine the changes in stability as a reflection of early healing around single-stage, roughened-surface implants in humans utilizing resonance frequency analysis (RFA). RFA makes use of a transducer, attached to an implant, which is excited over a range of sound frequencies with subsequent response analysis. MATERIALS AND METHODS: Twenty patients had 1 to 4 implants placed in the posterior maxilla or mandible. Bone type was classified into 1 of 4 groups according to the Lekholm and Zarb index (1985). RFA was used for direct measurement of implant stability on the day of implant placement and consecutively once per week for 6 weeks and at weeks 8 and 10. RESULTS: Twenty-seven ITI SLA implants placed in the premolar and molar regions of the maxilla and mandible were evaluated. Early failure occurred with 1 implant related to parafunction. The remaining 26 implants were distributed as follows: 29.6% in Type 1 bone, 37% in Type 2 or 3 bone, and 33.3% in Type 4 bone. The lowest mean stability measurement was at 3 weeks for all bone types. The percentage decrease in stability from baseline to 3 weeks was highest for Type 4 bone (8.6%), as was the percentage increase in stability from 3 to 10 weeks (26.9%). A Bonferroni adjusted Student t test comparison of bone groups at each time point revealed highly significant differences between implant stability in Types 1 and 4 bone at 3 weeks (P = .004) and a moderately significant difference between Types 2, 3, and 4 bone (P = .08) at 3 weeks. Implant stability did not change significantly during the 10-week period in Type 1 bone (P > .10). With the same test, by 5 weeks, no bone groups showed any difference in implant RFA measurements (P = 1.0). DISCUSSION: This study demonstrated the lowest values for implant stability at 3 weeks after placement for all bone types. This effect was statistically significant and most pronounced in Type 4 bone. CONCLUSION: There was no significant difference in the pattern of stability changes among different bone types after 5 weeks of healing.

Acid Etching, Dental↗
PubMed2003

Advanced crown and bridge design.

The present article describes the CAD construction procedure of copings, reduced crowns, anatomical crowns, hybrid bridges, and other construction software features contained in the Digident dental CAD/CAM system (Girrbach Dental, Pforzheim, Germany). The individual design of a crown or a bridge framework will, of course, influence the stability and the longevity of the final dental restoration. Especially an anatomically reduced crown framework possesses--in comparison to a simple coping design--several advantages, while for some materials, a full crown design is esthetically not suitable. An anatomically reduced crown design results in a mechanical support of the occlusal cusps, as the high strength framework is mechanically more favorable than the veneering ceramics or composites. Moreover, the reduced construction of the anatomical shape allows the creation of ceramic layers of approximately homogeneous thickness. This has the effect that the residual stresses in the veneering ceramic after the thermal treatment, i.e., several firing and cooling cycles, are minimized. A prerequisite for the computer-aided anatomical construction of crowns is the inclusion of adjacent teeth and the articulation of the opposing jaw. In these terms, the opposing jaw or a bite impression have to be scanned, digitized, and positioned virtually in bite relation. While taking patient-specific articulator parameters into account, a software-integrated "virtual articulator" allows simulation of dynamic occlusion and therefore a computer-aided reduction of interfering contact points.

Computer-Aided Design↗
PubMed2003

[A study on microstructures and heat reaction zone of laser-melted and cast post-keepers].

OBJECTIVE: In order to introduce the laser welding technology into root-cap making, this study compared the surface characters and internal structures of laser-melted and cast post-keeper to provide experimental data for clinical application of the technique. METHODS: Using untreated keeper as the control group, the surface characters and metallographic structures of the keepers were examined by stereomicroscope, metallographic microscope and SEM, and element analysis were conducted with EPMA. RESULTS: The laser-melted post-keeper basically kept the original smooth and the internal structure of the keeper, the heat reaction zone was extremely small and elements diffused mutually around the fusion zone obviously. While in the cast post-keeper, the surface was rough and had an oxide-layer. The internal structure changed and a fusion band formed between the base alloy and the keeper, but element diffusion was limited to the fusion zone. CONCLUSION: Compared with casting, laser welding technique demonstrated less influence on the surface and internal structure of the keepers.

Dental Alloys↗