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Biomedical subjects

A H Geering

Publications and source records attributed to A H Geering.

At least 19 recordsLinked to original sources
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↗
PubMed1985

Cultivable microflora of plaque from full denture bases and adjacent palatal mucosa.

Anaerobic cultural techniques and rapid biochemical identification tests normally employed for periodontal plaque were utilized for the analysis of plaque samples taken from denture bases and corresponding adjacent mucosa. Results were compared with those or more comprehensive microbiological investigations. Forty four samples were obtained from the denture bases and adjacent palatal mucosa of 12 patients wearing full upper dentures. The specimens were then collected in Reduced Transport Fluid and processed in the anaerobic glove box. Samples were plated on Enriched Trypticase Soy Agar (ETSA) and cultured under both aerobic and anaerobic conditions. In addition plaque samples were plated on Sabouraud medium. Facultative bacteria predominated in both denture and palatal plaques. Significantly greater numbers of cocci were recovered in the samples from palatal mucosa. More rods were found in denture plaque. Anaerobes were present in both instances. Among the anaerobes, saccharolytic Bacteroides were identified with the highest frequency, while Veillonella species were present in the greatest quantity. Recovery of yeasts was similar for both ETSA and Sabouraud media incubated aerobically. As has been found in other microbiological studies Candida albicans represented only a minor part of the total cultivable flora.

Actinomyces↗