Occlusion of artificial teeth in partial dentures in the "chewing center"--first exploratory population-based evaluations.

Occlusal performance is a substantial determinant of the quality of dental prosthetic restorations. In the follow-up (SHIP 1) to the Study of Health in Pomerania (SHIP), a representative population of 3300 subjects was studied in the first exploratory evaluation of the occlusion of artificial teeth in the chewing center (first molar region) of partial dentures. A digital analysis of interocclusal records of habitual intercuspation position (ICP) was performed using the Greifswald Digital Analyzing System (GEDAS), a software package that identifies contact points as transparent areas. 562 subjects (280 men aged 61.7 ± 11.9 years and 282 women aged 60.7 ± 10.7 years) had maxillary removable partial dentures (RPDs), and 619 (271 men aged 65.0 ± 11.5 years and 348 women aged 62.4 ± 10.6 years) had mandibular RPDs. Most RPDs were retained with either attachment retainers (11.7% maxilla, 11.7% mandible), cast clasps (38.4% maxilla, 40.7% mandible), telescopes with double crowns (15.7% maxilla, 19.1% mandible), or wrought wire clasps (16.4% maxilla, 8.2% mandible). Some had a combination of different retention elements. The mean number of artificial teeth was 7.8 ± 2.9 in the maxilla and 7.5 ± 3.0 in the mandible. Only the artificial teeth (first molars) in mandibular partial dentures showed differences in the frequency of occlusal contacts between groups (chi-square test). Of these, telescopic crown-retained RPDs had the highest frequency of occlusal contacts (74.4% at tooth 36 and 77.1% at tooth 46), and wrought wire-retained RPDs had the lowest (48.4% at tooth 36 and 45.2% at tooth 46). The results for RPDs with a free-end saddle were comparable and analogous; contact frequencies for those with an interdental saddle did not differ significantly. Notably, the overall frequency of occlusal contacts was greater for tooth 46 (62.9%) than for tooth 36. In conclusion, when replacing teeth in the chewing center, particularly in the mandible, telescopic crown-retained RPDs offer a distinct advantage in terms of occlusal contacts and thus provide better occlusal stability.

Biodynamics of attachments used in overdentures: experimental analysis with photoelasticity.

Treatment with overdentures is an alternative to conventional complete prostheses. Different types of attachments can be placed in natural teeth that act as retainers for overdentures. The photoelastic relationship between the design of the attachment and the distribution of occlusal forces among the abutment teeth and the distal alveolar ridges was examined. The results were used to develop a classification for clinical cases so that the correct attachment design can be selected.

[The use of bar attachment in removable dentures]. / Primenenie zamkovogo krepleniia v s''emnom protezirovanii.

The results of treatment of 230 patients with dentition defects are presented. Plate, arch, and removable bridge dentures were used fixed with a special clammer suggested by the authors. The follow-up has shown good functional and esthetic characteristics of the suggested denture designs.

Incidence of various classes of removable partial dentures.

The purpose of a classification for removable partial dentures (RPDs) is to simplify identification and enhance its teaching. A classification also allows a longitudinal comparison of various classes of RPDs to determine whether the teaching of RPD design is consistent with the relative frequencies of RPD use. This study surveyed the types of removable partial dentures being fabricated in a regional dental laboratory and compared these findings with data from previous studies. Results indicate that mandibular RPDs are more common than maxillary RPDs and the class I mandibular RPD is the most common type of RPD for either dental arch. A palatal strap was the most frequently used maxillary major connector and a lingual bar was used three times more often than a lingual plate in the mandibular arch. Cast circumferential clasps were used twice as often as RPI clasp designs. The percentage of Kennedy class I RPDs was 40%, class II 33%, class III 18%, and class IV 9%. Comparisons with a previous study indicate the percentage of Kennedy class II has increased, whereas class I, class III and class IV RPDs have not changed significantly. Findings of the study indicate that the frequency of use of the various types of RPDs have changed in the past 30 years.