Search PubMed⌕ Search

Biomedical subjects

R Mericske-Stern

Publications and source records attributed to R Mericske-Stern.

At least 37 records · Page 2Linked to original sources
PubMed1993

In vivo measurements of maximal occlusal force and minimal pressure threshold on overdentures supported by implants or natural roots: a comparative study, Part 1.

Numerous investigations give evidence of improvement of masticatory performance when edentulous patients have had implants placed. A comparative study was carried out to investigate the oral function and tactile sensibility of patients restored with implant-supported overdentures. Twenty-six patients with ITI implants and 18 patients with natural-tooth roots were selected. The minimal pressure threshold perceived in vertical and horizontal directions was registered with dynamometers. Maximal occlusal force was recorded with a miniature bite recorder placed between each pair of antagonistic teeth on both jaw sides separately. All measurements were repeated three times and the average was calculated. The records of minimal perceived pressure revealed a significantly higher threshold (factor 100) for the implant group. In both test groups, values registered in the vertical direction were slightly increased. A tendency for test subjects with implants to reach higher maximal occlusal force was observed, but not at a statistically significant level. In both test groups, the average maximum was found on the second premolar. The minimal pressure threshold seems to depend on the presence of receptors in the periodontal ligament. The records of maximal occlusal force, which were similar in both test groups, lead to the assumption that the limitation in maximal occlusal capacity of overdenture wearers is multifactorial and does not depend on the presence of a periodontal ligament.

Aged↗
PubMed1993

Forces on implants supporting overdentures: a preliminary study of morphologic and cephalometric considerations.

It is usually suggested that loading forces be transmitted to implants in the vertical direction. In 44 subjects treated with mandibular implants and overdentures, the inclination of the implant axis relative to the occlusal plane of the corresponding prostheses was measured by means of cephalometric radiographs. The degree of mandibular atrophy was also assessed. Peri-implant parameters such as plaque index, bleeding scores, and probing depths were registered on four implant sites. About 70% of the implants showed a buccal inclination, 11% showed a lingual inclination, and only 19% were found with an angle of 90 degrees. After an observation period of 5 years, no positive relationship between inclination of the implant axis, mandibular atrophy, and peri-implant findings could be established. Aspects of facial morphology and the interalveolar relationship of both jaws should be considered additional parameters and should be included in investigations concerning functional dynamics of removable dentures.

Aged↗
PubMed1993

Overdenture abutments and reduced periodontium in elderly patients. A retrospective study.

Among elderly patients attending a private office, a large number was seen having only few remaining teeth with advanced reduction of periodontal support. The long-term effect of overdenture rehabilitation within a mean observation time of 5.9 years (2 to 10 years) could be assessed in 109 patients (average age 74.1 years) wearing a total of 125 overdentures. After completion of treatment, 76% had regularly followed the maintenance care program. The degree of bone loss of the selected abutment teeth was assessed by means of radiographs. 56% showed a highly reduced periodontal support with bone loss of more than 50% of the root length. No, or moderate loss of periodontal support was found in only 9.5%. The overdentures were initially retained by 359 cast gold copings. Biologic and technical failures were registered for 54 copings and examined with regard to the reduction of periodontal support of the abutment teeth. Repair and treatment were prescribed for 30 copings, including guided tissue regeneration for 6 abutments. Twenty-four abutment roots with copings were extracted. Although most biologic failures were encountered in abutment teeth with severe reduction of the periodontium, the failure rate was not statistically higher for these abutments.

Aged↗
PubMed1992

Three-dimensional force measurements on mandibular implants supporting overdentures.

The purpose of this study was to determine masticatory and functional forces in three axes on mandibular implants supporting overdentures. Five edentulous test subjects were selected, each having two mandibular implants. Three-dimensional piezoelectric force transducers were mounted on the two-part ITI Bonefit implants and rigidly connected to the denture. Forces in vertical, lateromedial, and anteroposterior directions were measured by means of electrostatic plotter records. The test modalities were light tapping, grinding, maximal occlusal force, and chewing test food. Results showed that the five subjects developed similar stress patterns but quantitatively different occlusal and chewing forces. In all but one subject, reduced maximal occlusal force was found compared to dentate subjects and edentulous subjects with fixed partial prostheses supported by implants. The recordings of chewing cycles when eating test food resulted in very regular rhythmic strokes, similar to those of dentate subjects but with slightly reduced speed. All stress patterns showed that occlusal and chewing forces were mainly directed in vertical, medial, and anterior dimensions. The dominating component was vertical.

Aged↗
PubMed1990

Microbiological features of stable osseointegrated implants used as abutments for overdentures.

The microflora associated with osseointegrated implants used as abutments for overdentures was investigated in 18 edentulous patients, 2 years after implantation. 52.8% of the organisms cultured were facultatively anaerobic cocci and 17.4% were facultatively anaerobic rods, while Gram-negative anaerobic rods accounted for only 7.3%. Fusobacterium sp. and Bacteroides intermedius were both found in 8.8% of the samples. B. gingivalis and spirochetes were not found. Repeated microbiological and clinical data were collected in 9 patients during the 3rd, 4th and 5th year after implantation. No significant time trends were noted. Separate samples taken within the same patient from different sites were similar. Therefore, bacteriological independence of sites could not be assumed for the conditions investigated.

Dental Abutments↗
PubMed1990

Clinical evaluation of overdenture restorations supported by osseointegrated titanium implants: a retrospective study.

This paper reports the results of using osseointegrated titanium implants as abutments for overdenture restorations in the mandibles of 62 edentulous patients. All of these patients were edentulous for several years and required complete dentures. Six months after prosthodontic treatment, two implants (ITI, Straumann) were placed with consideration of the denture base and morphologic aspects of the mandibular residual ridge. The retention devices consisted of a bar connector or single ball-shaped precision attachments. Three or four implants splinted with a bar were placed in a control group of 11 patients. Attached keratinized gingiva (greater than or equal to 2 mm) surrounded approximately 48% of the buccal and 55% of the lingual implant sites. Evaluation after periods of 6 to 66 months postoperatively revealed good clinical results with five patients lost to recall in 1989. Two implants were lost after overdenture insertion. The findings suggest that two implants may adequately serve as retention for a mandibular complete denture and that attached gingiva surrounding the implants does not seem to be prerequisite for healthy function.

Adult↗
PubMed1990

[The aftercare findings and recall behavior of older patients with removable dentures].

Data were collected from 285 patients (average: 63.8, range: 23 to 87) who received prosthodontic treatment at the Clinic for Removable Prosthodontics of the University of Bern during the years of 1981 through 1987. 62 edentulous patients received two osseointegrated implants in the lower jaw. For the partially edentulous patients, removable partial dentures (RPD-89 patients) or overdentures (OD-134 patients) were prescribed. These two groups received recall care for a period of 2 to 3 years after insertion of the dentures. Due to limited capacity of the university clinics, a great part of these patients were then referred to private practitioners. All patients from the student course, however, were carefully checked during the year after insertion of the denture. Implant patients received a regular recall throughout the observation time. The patients' behaviour was not up to the dentists' expectations: less than 50% of the RPD and OD patients followed the recall appointment regularly. In contrast, the implant patients participated 100% in the recall. The plaque and bleeding indexes were much higher in the partially edentulous than in the implant patients. RPD and OD patients with regular recalls scored significantly better, but never reached the same level of results as the implant patients. Nevertheless, the probing depths on implants were a bit higher compared to those of the natural teeth, but not significantly.

Adult↗
PubMed1989

[The elderly patient in private practice].

The aim of this study was to get an overview on therapeutic measures and recall compliance of elderly patients treated in a private dental office. Data regarding the dental treatment und prosthodontic rehabilitation were collected from a total of 429 patients who were 65 years old and older (average: 75.8 years). 94 patients (23%) were edentulous and had dentures in both jaws, whereas 335 patients still had remaining teeth in one or both jaws. Only 8 patients had a full complement of teeth. 239 patients (55%) had complete oral rehabilitation. Few fixed partial prostheses and mainly removable partial und complete dentures were inserted. 190 patients did not get new reconstructions, because 1) they did not need it, or 2) they did not want it. In some cases, existing prostheses could be adapted or repaired. Almost all patients with remaining teeth were in need of periodontal treatment. 54% of them underwent periodontal therapy. Maintenance care was supported by regular recall. 65% of the patients appeared regularly according to their individual interval. A strong correlation could be established between regular recalls, the extent of rehabilitation and the number of remaining teeth.

Aged↗
PubMed1989

[Osseous integration].

Explore the source record for details and available documents.

Dental Implantation, Endosseous↗
PubMedDate not supplied

Life table analysis and clinical evaluation of oral implants supporting prostheses after resection of malignant tumors.

Seventeen mostly elderly patients, 13 men and 4 women, were consecutively admitted for implant-prosthodontic treatment after they had undergone resection of malignant tumors in the oral cavity. A total of 53 dental implants (ITI-Straumann) was placed, 12 in the maxilla, 41 in the mandible. The prosthetic rehabilitation consisted of overdenture therapy in 15 patients, and 2 patients were treated with fixed partial prostheses. Thirty-three implants were prescribed for patients who received radiotherapy either before or after implant placement. The average dose varied between 50 and 74 Gy. Eighteen implants were located in grafted bone from the fibula, scapula, or hip. For 2 patients, hyperbaric oxygen therapy was also prescribed after osteoradionecrosis had developed. One implant was lost before prosthetic loading. During an observation period of up to 7 years after loading, 3 more implants were removed. All implant losses occurred in the mandibles of patients who had received radiotherapy. A life table analysis was performed, and the cumulative survival rates, calculated for 2, 3, and 5 years, were 93%, 90%, and 90% respectively. No failures or complications were observed with technical components of the implants or prostheses. All prostheses could be maintained during the entire observation time. Although in the present investigation the survival rate of implants was slightly lower than under standard conditions, the treatment with implant-supported prostheses seemed to be advantageous for patients who had undergone intraoral resections.

Adult↗
PubMedDate not supplied

Effectiveness of maxillary overdentures supported by implants: maintenance and prosthetic complications.

PURPOSE: The aim of this study was to evaluate the prosthetic complications with implant-supported overdentures in the maxilla. MATERIALS AND METHODS: Forty-one patients (mean age 61 years) were consecutively admitted for treatment from 1991 to 1998. A total of 173 ITI implants were placed. Four to six implants either connected with a bar (34 overdentures) or with single anchors (seven overdentures) supported the denture, and only a few parties had fewer than four implants. The overdentures had a horseshoe design and were reinforced by a cast-metal framework. The mean observation time was 3.2 years. Oral hygiene and periimplant parameters were regularly assessed, and records were kept of prosthetic maintenance service. All prosthetic complications encountered were classified related to (1) implant components and anchorage devices, (2) mechanical and structural failures of dentures, or (3) denture-related adjustments. RESULTS: Three implants did not osseointegrate, and five implants were lost after loading. Thus, the overall survival rate of the implants was 95.5%. Altogether, 85 prosthetic complications were encountered. The most frequent finding was retightening of the bar screw and adjustments of the bar retainers. Repair of dentures was not frequent and was mostly related to broken teeth. No fracture of dentures was observed. Renewal of dentures occurred twice, once after loss of all implants in one patient. Thirty-nine overdentures had been continuously worn; thus, the overall denture stability was 95%. Mucosal irritation and need for occlusal adjustment were the most frequent findings in the first year. Over time, a decrease of complications was observed. CONCLUSION: Planned maxillary overdentures supported by implants are a successful treatment modality on a short-term basis.

Acrylic Resins↗