Search

Purpose: This retrospective study investigated the frequency and time history of chipping and facing failures, recurrent caries (RC), periodontitis (PE), and loss of retention (LR) of porcelain-fused-to-metal (PFM) single crowns., Materials and Methods: A total of 997 PFM single crowns had been inserted according to a standardized treatment protocol from January 1984 to May 2009. The frequency and time history of chipping and facing failures were evaluated, as were possible risk factors from historical clinical data. Risk factors were bruxism, the type of antagonist, and the location of crowns (mandible, maxilla, anterior, posterior). The survival times of crowns were estimated using Kaplan-Meier (KM) analysis., Results: The median follow-up time calculated with the inverse KM method was 4.33 years. Anterior and posterior PFM crowns showed 5-year survival rates (time to crown replacement) of 96.4% and 97.5% and 10-year survival rates of 92.3% and 95.9%, respectively. Chipping was found in 17 (1.7%) of the 997 PFM crowns. According to the KM method, the 5- and 10-year free-of-event-rates for chipping of anterior crowns were both 98.9%, and the rates for posterior crowns were 98.2% for 5 years and 97.3% for 10 years. Thirteen patients showed RC (1.3%) and 144 (14.4%) PE. The 5-year free-of-event-rate for RC was 98.7% and the 10-year free-of-event rate was 97.2%. For PE, the 5-year free-of-event-rate was 85.8% and the 10-year free-of-event rate was 72.2%. The 5- and 10-year free of- event-rates for LR were 92.2% each for anterior teeth and 97.1% each for posterior teeth., Conclusions: Patients with PFM crowns may expect long-term survival for their restoration. Clinical complications are rare. Chipping of the veneer or loss of retention may occur during the first few years. While chipping of the veneer may occur during the first few years, the frequency of caries or periodontitis increases with the length of oral service and with age.

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.

Removable partial denture production in western Germany was studied by analyzing 1,082 photographs taken in consecutive series at five large dental laboratories. The photographic technique was standardized, enabling evaluation of the casts as well as the design of the dentures. Of the casts, 47.2% were maxillary and 52.8% were mandibular. The mean number of teeth present was 6.29 in the maxilla and 6.57 in the mandible. In the maxilla, 52.9% of the molar regions were edentulous; i.e., they had distal-extension free-end spaces. The corresponding figure for the mandibles was 72.7%. Most of the maxillary removable partial dentures had a palatal strap or a palatal plate, and most of the mandibular dentures had a lingual bar. Of the removable partial dentures, 53.1% were retained by telescopic crowns, 15.3% had precision attachments, and 36.1% were retained by clasps only.

The prevalence of prosthetic reconstructions among 1534 German recruits (mean age 21.8 years) was evaluated. Of the total number of single crowns (n = 552), 72% were found in the upper jaw. Forty-one per cent of the crowns were situated in the upper incisor region. Four per cent of the probands received mostly three-unit-bridges and 0.9% removable partial dentures. In 3.7% of the cases all missing molars of a quadrant were not prosthetically replaced. The number of single crowns and bridges was not associated with the final school education, which in its term is closely associated with the social stratum. Between the level of school education and the need of prosthetic treatment a highly significant association was found.