Search PubMed⌕ Search

Biomedical subjects

A H Geering

Publications and source records attributed to A H Geering.

At least 19 recordsLinked to original sources
PubMed2001

Long-term evaluation of non-submerged hollow cylinder implants. Clinical and radiographic results.

From 1974 various types of hollow cylinder ITI-implants were placed before the new generation of Bonefit ITI-implants was developed in the mid-eighties. The aim of this study was the clinical and radiographic evaluation of hollow cylinder implants that were inserted during the time period of 1978-1987 in partially and completely edentulous patients to support overdentures, fixed partial prostheses and single crowns. Altogether, 71 patients with a total of 132 hollow cylinder ITI-implants still in situ had been followed regularly during the entire observation period of 11.4 to 19.7 years (mean 14.1). Thirteen implants had to be removed before an observation period of 10 years was completed, 4 additional implants were lost after being in function for over 10 years and two further implants were considered to be failures at the time of the examination. Thus 91.4% of the implants were still in situ after 10 years and the survival rate for a mean observation period of 14.1 years was 84.6%. Periimplant parameters were used to assess the clinical conditions of the implants. On the radiographs, horizontal bone loss or angular defects could be detected on 40% of all implants if compared to the base-line situation. The probing depths around these implants were significantly increased compared to implants with an unchanged bone level, however the mean probing depths did not exceed 3.5 mm and 2.8 mm respectively. From this clinical evaluation one may conclude that with the early generation of hollow cylinder ITI-implants favorable long-term results were achieved.

Adult↗
PubMed1998

Open reduction without fixation of dislocated condylar process fractures: long-term clinical and radiologic analysis.

PURPOSE: This study evaluates the long-term results of open reduction without fixation for displaced fractures of the condylar process. PATIENTS AND METHODS: Clinical and radiologic examinations were performed on 27 patients with 29 operated joints an average of 6.7 years postoperatively. The postoperative result was evaluated on the basis of occlusal and joint function, as well as radiographic assessment of condylar changes. RESULTS: Clinically, satisfactory results were achieved. Radiologically, despite correct intraoperative alignment of the fractured segments, a slight medial deviation of the condylar process was found on the posteroanterior radiograph. However, in only two cases was a 20-degree deviation observed. On final follow-up, 48% of the cases had a normal condylar configuration radiologically, and in the remaining cases, normal function was established even though there were condylar changes. Fully exposed and devascularized condylar processes generally showed more severe changes than those in which partial vascularization was maintained. CONCLUSION: The surgical management described enables a satisfactory outcome to be achieved with dislocated condylar process fractures.

Adolescent↗
PubMed1995

A review of masticatory ability and efficiency.

Masticatory function can be assessed by chewing tests and questionnaires or personal interviews. Whereas the chewing tests allow the assessment of masticatory efficiency with some objectivity, questionnaires help evaluate a person's subjective responses about chewing ability. Epidemiologic studies indicate a subjective decrease in chewing ability with increasing degree of tooth loss, a trend that was confirmed in the literature. Of interest was that the subjective measures of masticatory ability are often overrated when compared with the functional tests. Masticatory function is a patient factor rather than a parameter that prosthetic treatment can qualify. It depends on a variety of personal and subjective factors that can hardly be influenced by the practitioner. This article describes and discusses scientific sociophysiologic and biomedical approaches to evaluating masticatory function.

Bite Force↗
PubMed1994

Degenerative temporomandibular joint disease: surgical treatment and long-term results.

PURPOSE: In this study, the long-term evaluation after surgical treatment of temporomandibular joint with manifested degenerative changes and internal derangement is described. The surgical procedure, including extensive exploration and remodeling of the joint, with interposition of lyophilized human costochondral cartilage, is described. MATERIALS AND METHODS: Thirty-two cases (37 joints) were evaluated at a mean follow-up time of 3.1 and 8.6 years after the surgical treatment. RESULTS: A significant reduction of dysfunction and pain symptoms was achieved in most cases.

Adolescent↗
PubMed1994

Peri-implant mucosal aspects of ITI implants supporting overdentures. A five-year longitudinal study.

Sixty-six ITI implants placed in the mandible of 33 edentulous elderly patients (mean age: 69 years) were observed longitudinally for 5 years. The implants served as overdenture anchorage either by means of a connecting bar or single spherical attachments. During the study period, 2 implants failed (one because of a peri-implant lesion and one because of a fracture) and had to be removed. At the beginning of the study, all implants were osseointegrated and had successfully been in function for 3-5 months. Oral hygiene practices and the peri-implant mucosal status were assessed according to the criteria of conventional periodontal parameters. Approximately 50% of the implants had been installed into lining mucosa and hence were to surrounded by keratinized mucosa. The peri-implant mucosal tissue was maintained healthy during the whole observation period, and no or only minimal loss of attachment was observed. The probing depths averaged approximately 3 mm. At the end of the study, orthopantomographic radiographs were obtained from all patients to assess the peri-implant bony structures. Small local angular bony defects were detected on 16 implants (22%) in 12 patients. Slightly increased probing depths were observed when angular bony defects were present. Loss of attachment was significantly less frequent when the implants had been placed following a prolonged period of edentulousness (> 5 years). This study demonstrated that advanced age, reduced dexterity of elderly patients and environmental conditions of overdentures do not represent a higher risk for the development of peri-implant lesions.

Aged↗
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↗
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↗
PubMed1991

[The periodontal status of the population of 12 cantons in Switzerland].

An epidemiological survey in 12 cantons of Switzerland yielded a high percentage of all the sites examined with signs of gingivitis. Nevertheless, only 4% of all the sites showed periodontal breakdown of 7 mm or more; however, those sites were distributed in larger proportions of the population sample. Further frequency analysis revealed that more than 75% of the persons examined yielded no or only few sites with periodontal breakdown. The results of this study indicate that despite the high percentage of inflamed gingival units in the population, periodontal breakdown is less frequent than commonly estimated.

Age Factors↗
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↗
PubMed1990

[A comparison of the adhesive strength of unaged and aged metal-resin bonding systems. An in vitro study].

The tensile strength and shearing strength of six bonding systems for the acrylic resin to metal bond were tested, unaltered and after cyclic thermal shock. The methods were 1) sandblasting with 50 mu and 2) 250 mu aluminium oxide granules, 3) electrolytic etching, 4) the RBS system, 5) the Sebond-MKV system, and 6) silicoating with the Kulzer Silicoater system. The materials to bond were Paladur, an autopolymerizing methacrylate, and the cobalt chromium alloy Wisil M. It was found that sandblasting gave good constant results depending on the size of the Al2O3 granules. RBS did not improve the tensile strength. The other tested systems improved the average values by a factor 3.5 in comparison to sandblasting. Silicoating showed a wide scattered range. The values of Sebond were increased and constant. After thermocycling the values were up to 30% better, but only when the recommended opaquer was not used. Sandblasting could give a good reference as baseline for comparative studies.

Acid Etching, Dental↗
PubMed1990

Comparison of clinical periodontal parameters with the Community Periodontal Index for Treatment Needs (CPITN) data.

The purpose of this analysis was to assess the ability of the CPITN system to rate severity and prevalence of periodontal diseases in a population, in comparison with full mouth scorings using conventional clinical parameters (Plaque Index, Gingival Index, Retention Index, Pocket Probing Depth and Loss of Attachment). These parameters were collected in a randomly selected sample in Switzerland. The data were then transformed to fit the definitions of the CPITN. Furthermore, a comparison of the data set from Switzerland with data obtained from the Oral Global Data Bank of the WHO was made. By conversion of the Swiss data into the CPITN format, many details were lost, which were considered to be relevant to assess severity, prevalence and localization of periodontal diseases within a population. In addition, the transformed data generally overestimated the prevalence of periodontal destruction when compared with data from surveys in other industrialized countries in which the CPITN was used to evaluate the periodontal status. The comparison of the data before transformation into the CPITN, however, corroborated results from epidemiological studies in which conventional periodontal index systems were used. This indicates that data obtained to determine defined treatment needs (CPITN) may be of questionable value for the assessment of the true prevalence and severity of periodontal disease in a population.

Dental Health Services↗
PubMed1988

Periodontal conditions in a randomly selected population in Switzerland.

The aim of the present study was to evaluate the periodontal conditions of a randomly selected population in the Canton of Berne, Switzerland. From a total of 350 selected persons, 206 (59%) attended the examinations. The Plaque Index (PlI), Gingival Index (GI) and Retention Index (RI), the width of the keratinized gingiva, pocket probing depth (PD) and loss of probing attachment (LA) were recorded on four surfaces per tooth in the entire dentition of the subjects. The statistical analyses were performed using the Statistical Analysis System (SAS). A total of 4253 teeth were scored. On average the patients had 20.7 teeth. The mean PlI of this population was 1.16, the mean GI was 1.34 and the mean RI was 0.81. All three indices were higher in older age groups. 72% of all measurements for pocket probing depths were less than or equal to 3 mm, 26% were between 4 and 6 mm, and only 2% were more than 6 mm. 76% of all sites had lost less than or equal to 3 mm of probing attachment, 21% of the sites had lost between 4 and 6 mm and only 3% had lost more than 6 mm. There were no statistically significant differences either between females and males or between the rural and the urban populations. These results indicate that only a relatively small percentage of the sample representative for the respective area in Switzerland suffered from advanced periodontitis, while the great majority may be treated by rather conservative approaches to periodontal therapy.

Adult↗