[Retention of the complete upper prosthesis: "the posterior joint"].
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Cheek↗
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[Results of the double J catheter as an internal urinary bypass].
A catheter in double J was used as an endoureteral prosthesis for internal urinary shunt in 118 patients (136 catheters), including 35 with malignant and 83 with benign affections. Catheterization was unilateral in 100 cases and bilateral in the remaining 18. The catheter was left in situ for between 1 and 645 days (mean 93 days), introduction being endoscopic in 72 cases, surgical in 50, percutaneous in 11 and combined endoscopic/percutaneous in 3. Complications related to introduction of prosthesis were ureteral perforation (1 case) and absence of bypass of obstacle (4 cases). Complications related to retention of prosthesis were mictional symptomatology or lumbar pain in 18 cases and urinary infection in 11. Results were rated as good in 99 cases (84%) the catheter fulfilling its mission of tutor and drainage, while in 19 cases (16%) results were poor due to bad insertion or obstruction.
Adolescent↗
The fate of osseointegrated implants in patients following oral cancer surgery and mandibular reconstruction.
BACKGROUND: The feasibility of implant treatment in patients after oral ablative tumor surgery and defect reconstruction has not yet been investigated in terms of the requisite high standards of success assessment. A report on this topic must address not only implant survival but implant health, bone response, soft tissue health, failure pattern, and time of failure, as well. METHODS: From June 1990 through December 1997, 90 patients received 320 dental implants after oral tumor resection and immediate soft tissue reconstruction. Included in the study were 45 patients with 162 implants loaded for at least 1 year. Regular follow-up for 6 years consisted of detailed medical history and evaluation of periodontal parameters. Out of this population, 10 vascularized iliac bone grafts for mandibular reconstruction containing loaded implants were selectively evaluated for bone loss. RESULTS: The assessment of pocket probing depths, plaque accumulation, bleeding disposition, implant mobility by means of the Periotest method applied to the restoration type, horizontal and vertical (peri-implant) bone loss according to x-ray findings, causes and time of implant loss, and subjective statements offered results comparable to those found in healthy subjects examined with periodontal success parameters. CONCLUSION: Prosthetic restoration of patients after oral ablative tumor surgery followed by hard and soft tissue reconstruction can be achieved with dental implants with similar long-term efficacy as found in healthy subjects adhering to internationally established requirements.
Adult↗
Long-term changes of hydroxyapatite-coated dental implants.
There are many controversies about the long-term prognosis of hydroxyapatite (HA)-coated implants. Failure may be related to compositional and structural changes of the coating occurring during implantation. Two retrieved and two unused HA-coated blade-type implants were examined by stereomicroscopy, secondary electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electron probe microanalysis. The objective was to investigate the HA morphology, composition, and structure, and to characterize the changes that occurred in the retrieved implant coatings. Retrieved implants presented partial loss of the coating, especially at the apical and mesiodistal edges. Remaining HA was thick and flattened in the cervical and central areas and gradually thinner and rougher towards the apical and mesiodistal edges. Increase of Cl and Mg, decrease of OH, and X-ray diffraction peak broadening were found in the retrieved implant coatings, in comparison with the unused implants. Morphological changes of the retrieved implants seem to depend on stress values in the surrounding bone and on implant mobility. Compositional changes and increased amount of lattice imperfections appeared in the retrieved implant coatings, as a result of ion substitutions in the apatite lattice. However, the present study could not confirm the influence of these changes on implant failure.
Coated Materials, Biocompatible↗
Effect of surface treatment on retention of glass-fiber endodontic posts.
STATEMENT OF PROBLEM: The effects of surface treatment on the retention of prefabricated fiber-reinforced epoxy resin posts are not well understood because most studies measure retention shortly after cementation, without artificial aging. PURPOSE: The purpose of this study was to evaluate the effect of surface treatment on the retention of glass-fiber endodontic posts luted with resin cement and subjected to artificial aging. MATERIAL AND METHODS: Thirty-two single-rooted teeth were selected, the coronal aspect of each tooth was removed, and the remaining root received endodontic therapy. Specimens were then divided into 4 groups (n = 8). Post spaces were prepared to a depth of 10 mm by using ISO 90 rotary instruments. The tapered posts received 1 of 4 surface treatments: cleaning with alcohol (Alc), cleaning with alcohol and conditioning with ED-Primer material (Alc-ED), airborne-particle abrasion (Air), or airborne-particle abrasion and conditioning with ED-Primer material (Air-ED). All posts were luted with a composite resin luting agent (Panavia F) after conditioning the canal dentin with autopolymerizing dentin primer (ED-Primer) and without acid etching of the canal dentin. After cementation, the specimens were stored in water at 37 degrees C for 30 days and subjected to simulated aging conditions consisting of 7500 thermal cycles (5 degrees C/55 degrees C) and 300,000 mechanical loading cycles with 30 N. Retention (N) of the posts was measured with a universal testing machine with a crosshead speed of 2 mm/min. The data were analyzed using 1-way ANOVA and the Tukey HSD test (alpha = .05). The dislodged posts were also examined microscopically at x8 and x20 magnification to evaluate the mode of failure. RESULTS: The mean retentive values (N) and SDs of the test groups were as follows: Alc, 375.9 +/- 85.0; Alc-ED, 421.2 +/- 46.8; Air, 534.8 +/- 65.8; and Air-ED, 555.8 +/- 86.9. Airborne-particle-abraded posts had significantly higher retention compared with nonabraded posts (P < .001). Treating the post's surface with ED-Primer material prior to cementation had no significant effect on retention. The failure mode was purely adhesive at the resin cement-post interface for all nonabraded posts. A mixed failure mode, adhesive at the resin cement-dentin interface, at the resin cement-post interface, and cohesive in the resin cement, was observed for airborne-particle-abraded posts. CONCLUSION: Treating the surface of the posts with ED-Primer material before cementation with Panavia F cement produced no significant improvement in the retention of the posts. Airborne-particle abrasion of the surface of the post significantly improved the retention.
Air Abrasion, Dental↗
Sectional prosthesis for total maxillectomy patients: a clinical report.
Total maxillectomy is a relatively uncommon surgical procedure and usually results in a surgical and prosthetic reconstructive challenge. The goals of prosthetic treatment include separation of oral and nasal cavities, which allows for adequate speech and deglutition, along with restoration of esthetics. Treatment of a patient with total maxillectomy due to verrucous carcinoma was presented in this clinical report. Clinical and laboratory procedures of the prosthetic treatment were described. The sectional prosthesis retained by magnets eliminated long-term use of a nasogastric tube, rehabilitated the patient's speech, and restored proper midfacial esthetic contour.
Aged↗
An evaluation of fit in osseointegrated implant components using torque/turn analysis.
PURPOSE: The accurate and passive fit of dental prostheses supported by endosseous implants is of primary importance in securing long-term restorative success. In the clinical setting, adequate visual and radiographic assessment of joined implant components can be limited. Mechanical engineering principles show a linear relationship between tightening and the degree of rotation of a precision bolted assembly. At a constant torque, with certain variables controlled, a threaded fastener should return to the same rotational end position on repeated tightenings. This study evaluated the terminal screw positions of joined implant components as a potential aid to the clinician in confirming the fit of a fixed and removable prosthesis. There were three areas of experimental inquiry: (1) How reproducible are the various clinical means by which torque is applied to the fastening screws, both in absolute and relative value? (2) How reproducible are the rotational end positions of the gold (attachment) and titanium (center) screws when a controlled torque is applied? (3) Do changes in screw position occur as a function of the magnitude of artificially introduced discrepancies? MATERIALS AND METHODS: Three different torque delivery devices were evaluated: a hand-held screwdriver (DIB 048; NobelpharmaUSA, Chicago, IL), a manual torque wrench (DIA 250; NobelpharmaUSA), and an electronic Torque Controller (DEA 020; NobelpharmaUSA), using a calibrated torque measuring dynamometer (Magtrol, Inc, Buffalo, NY). The reproducibility of turning limits were determined for both the titanium and gold screws contained in five Brånemark implant assemblies. Each assembly was subjected to six trials, tightening to recommended torque. The position of each screw head was recorded with a special scribe on acetate sheets and transferred to graph paper. Five implant assemblies were invested in dental stone within a die form mold. A casting was made supported by three implant analogues. Stainless steel shims of 12.7-microns, 25.4-microns, 38.1-microns, and 50.8-microns thickness were used to create impingement and space discrepancies. Controlled trials were conducted, and changes in rotational limits for each screw were recorded. RESULTS: The following values were measured, intending to achieve a torque of 10 Ncm, based on 10 trials for each implement: hand driver, 6.48 (+/- 0.85) Ncm; torque wrench, 7.77 (+/- 0.56) Ncm; and the Torque Controller, 8.54 (+/- 0.19) Ncm. The electronic Torque Controller proved to be the most reproducible instrument and was selected as the delivery vehicle for the remainder of the study. The titanium center screws had a rotational limit that was reproducible to within 0.6 degrees (+/- 0.2 degrees). For the gold screws, it was found that at least two trials had to be conducted for each assembly before the rotational limits conformed to a reproducible position within 1.85 degrees (+/- 1.87 degrees). A linear relationship of approximately 0.9 degrees/micron was observed between the changes in rotational limit and each subsequent shim thickness. CONCLUSIONS: This study suggests that screw position can be an indicator of fit in dental implant prostheses if the end point of screw rotation is adequately indexed, specific to each assembly and screw.
Analysis of Variance↗
Prosthetic rehabilitation of the oral cancer patient: a clinical report.
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Carcinoma, Squamous Cell↗
Retentive properties of three post-core systems.
The retention in root canals of Flexi-Posts, Para-Posts and Brasseler/Vlock-Posts was measured using tensile and compressive/shear forces. Forty-two extracted maxillary anterior teeth were embedded in self-curing acrylic resin and treated endodontically. Each root canal was prepared with the appropriate matching drills for the post-core system chosen. Each post-core was cemented in the canal with zinc phosphate cement. A tensile force was applied along the long axis of each tooth and the force needed to dislodge the post-core was recorded. There was no difference in retention between the small diameter posts, but the difference between the medium and the large diameter posts, however, was significant. In the medium diameter post group, the Flexi-Post was approximately twice as retentive as the other two post-core systems evaluated. In the second series of tests compressive/shear force was applied at an angle of 130 degrees to the long axis of the tooth. The retention difference between the small diameter posts was found to be statistically significant, Flexi-Posts being more retentive than Para-Posts and B/V-Posts.
Dental Prosthesis Retention↗
The passive fitting implant restoration.
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Bisphenol A-Glycidyl Methacrylate↗
Loose gold screws frequently occur in full-arch fixed prostheses supported by osseointegrated implants after 5 years.
The possible occurrence of loose gold and abutment screws retaining full-arch osseointegrated prostheses has been investigated. The prostheses had been in use for at least 5 years. The findings were related to clinical parameters such as accuracy of the superstructure, operator dependence, and clinical and radiological diagnosis of implant status after 5 years. The principles of the California Dental Association's (CDA) quality evaluation criteria were modified and applied in the study. Gold screw loosening was found to be related to framework misfit and was considered to be operator dependent to some extent. It is recommended that full-arch fixed prostheses be retightened after 5 years.
Aged↗
Comparison of titanium dowel retention using four different luting agents.
STATEMENT OF PROBLEM: Luting material, surface properties, and loading conditions affect the retention of prefabricated dowels to varying degrees. PURPOSE: The purpose of this study was to evaluate the effect of roughening of the dentinal walls and artificial aging on the retention of prefabricated tapered titanium dowels, using 4 different luting materials. MATERIAL AND METHODS: One-hundred twenty-eight single-rooted teeth were selected, the coronal aspect of each tooth was removed, and the remaining root received endodontic therapy. All specimens were divided into 4 groups (n=32). Dowel spaces were prepared to a depth of 10 mm using ISO 90 rotary cutting instruments. Tapered titanium dowels were luted with the following luting materials: zinc-phosphate cement (Harvard cement), glass-ionomer cement (Ketac Cem EasyMix), resin composite luting agent (Panavia 21) with autopolymerizing dentin primer (ED-Primer), or a self-adhesive composite luting agent (RelyX Unicem). Both composite luting agents were used without acid etching of the canal dentin. Each luting agent was used under 2 conditions: in 1 subgroup (n=16) the dentinal walls were not roughened, and in the other subgroup (n=16), walls were roughened with a diamond rotary cutting instrument. Eight specimens from each subgroup were stored in water at 37 degrees C for 3 days; the other 8 specimens were stored for 150 days and subjected to simulated aging conditions using 37,500 thermal cycles (5 degrees C/55 degrees C) and 300,000 mechanical loading cycles with 30 N. Dowel retention (N) was measured using a universal testing machine with a crosshead speed of 2 mm/min. Data were analyzed using 2- and 3-way ANOVAs and the Tukey HSD test (alpha=.05). RESULTS: The dislodged dowels were examined microscopically to evaluate mode of failure. The nonroughened dentinal walls showed no significant differences between the different luting agents. Roughening the dentinal walls increased the retention significantly for all groups. This increase was significantly higher for the resin composite groups (P=.0001). Storage for 150 days with thermal cycling and mechanical loading caused a significant decrease in dowel retention (P=.001). The failure mode was purely adhesive at the luting material-dentin interface for all dowels cemented in nonroughened root canals. A mixed failure mode, adhesive at the luting material-dentin interface and cohesive in the luting material, was observed for dowels cemented in roughened root canals. CONCLUSION: Roughening the dentinal walls and the use of resin luting cements provided statistically significant increases in dowel retention values.
Analysis of Variance↗
The anchorage quality of mini-implants towards translatory and extrusive forces.
AIM: The objective of the present experimental animal study was to investigate the stability of mini-implants (submersion depth 4 mm, Ø 3.3 mm) for orthodontic anchorage. Additionally the histomorphologic effects of orthodontic loading were to be analyzed, especially with regard to the activity and location of periimplant osteodynamic reactions. MATERIAL AND METHOD: 16 titanium implants (Orthosystem, Straumann, Waldenburg, Switzerland) were inserted in edentulous areas of the upper and lower jaw of four foxhounds. After a 6-month healing period the fixtures were loaded with extrusive forces (50 cN) in group 1, and with translatory forces (200 cN) in group 2. The osteodynamic changes during the 6-month force application period were documented using stains with calcium affinity (polychrome sequential labeling). The histologic analysis comprised: microsection method, fluorescence microscopy, toluidine blue staining, histomorphometry. RESULTS: All osseointegrated implants were stable throughout the test period. With respect to the apposition lines, the histomorphometric analysis showed more distinct osteodynamic activity in extrusively loaded than in translatorily loaded implants. The activity was more pronounced in the marginal area than in intermediate and apical implant areas. The extent of peri-implant remodeling activity was up to 980 micro m after extrusive loading and 300-700 microm after translatory loading. CONCLUSIONS: The results suggest that even mini-implants are suited to orthodontic anchorage tasks. The question of the required minimum size of orthodontic anchorage implants remains unanswered.
Alveolar Process↗
[Occlusion in osseointegrated prosthesis].
Occlusion plays a significant role in the successful restoration of natural teeth and in replacing missing teeth. Over the decades, standards for occlusion have been established. Implants, osseointegrated, have provided a rigid, usable abutment for restorations of occlusion and for the replacement of missing teeth. The natural tooth, due to it's mobility dynamics, presents problems related to occlusion. The osseointegrated, rigid implant, due to it's lack of mobility, presents in many respects problems related to occlusion. Substantial amounts of research has been presented on implants as it relates to success of osseointegration and acceptance by bone, and the acceptance of oral mucosal tissues to penetration of the implant. Failures of implant fixtures and their parts have been experienced. Not much information has been presented on the causes of failures. The question becomes obvious What is the role of the forces of occlusion? The purpose of this article is to present some aspects of occlusion that are important in restoring natural teeth and complete dentures. The problems in applying these aspects to the osseointegrated, rigid implant will be presented. The factors to consider in the control of the forces of occlusion in using implants will be established. It is not possible to cover all the possibilities of occlusion for implantation. However, the factors to consider in making intelligent choices will be presented.
Bite Force↗
Elongation and preload stress in dental implant abutment screws.
A common problem associated with dental implant restorations is loosening of screws that retain the prosthesis to the implant. A method was developed to determine initial preload on UCLA-type abutment screws by measuring elongation after applying known tightening torques with a digital torque gauge. Loosening torque was also measured after tightening to 32 N-cm torque for gold alloy abutment screws and 20 N-cm for titanium abutment screws. Gold alloy and titanium abutment screws were each used to secure a gold UCLA hexed abutment to a titanium implant. Stresses and forces were calculated from the elongation measurements for three regions of each screw. Elongation of the screws after applying the manufacturer's recommended tightening torques were within the elastic range. Induced stresses were 57.5% and 56% of the yield strengths for gold alloy and titanium, respectively. Tightening of screws beyond recommended levels may be possible without producing plastic deformation. At manufacturer's recommended torques, mean preload was 468.2 (+/- 57.9) N using gold alloy screws and 381.5 (+/- 72.9) N with titanium screws.
Dental Abutments↗
Mechanical state assessment of the implant-bone continuum: a better understanding of the Periotest method.
The aim of this study was to obtain a better understanding of the Periotest method when used to detect subclinical mobility of osseointegrated implants. Four hundred two screw-shaped implants were tested with the Periotest device at the time of abutment connection. Several factors, including jaw location, implant and abutment length, and gender, were related to Periotest values (PTVs). Implants located in the anterior region of the mandible showed the lowest mean PTV (-3.2). The influence of abutment and implant length upon PTVs could be detected in the maxilla. In the mandible, only abutment length had influence on PTVs. Women showed higher mean Periotest scores in the maxilla compared with men. This difference was not found in the mandible. The Periotest method, its clinical limitations, and the meaning of a given PTV are also discussed.
Adult↗
Fractures of the fixture component of an osseointegrated implant.
The cause of mechanical failure of the fixture component of an osseointegrated dental implant was investigated. The surfaces of five clinical specimens that had fractured were compared to those of new specimens fractured in the laboratory under monotonic and cyclic loads. Scanning electron microscopy revealed striations on the fractured surfaces of the clinical specimens, similar to striations on the laboratory-fatigued specimens and in contrast to the dimpled surfaces on the overloaded specimens. The investigation demonstrated that fractures of the fixture component of this dental implant occurred by fatigue under physiologic loads, with marginal alveolar bone loss around the fixture.
Alveolar Bone Loss↗
Gaining crown or bridge retention. An alternative to surgical crown lengthening.
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Cementation↗