A clinical evaluation of cobalt-chromium metal-ceramic fixed partial dentures and crowns: A three- to seven-year retrospective study

STATEMENT OF PROBLEM: In severely compromised dentition, loading of long-span and cantilever metal-ceramic fixed partial dentures (FPDs) could result in framework deformation and porcelain fractures. The use of cobalt-chromium (Co-Cr) alloys may be advantageous, but there is little information on the longevity of, and complications with, prostheses made with these alloys. PURPOSE: The aim of this retrospective study was to report the survival and complication rates of Co-Cr metal-ceramic FPDs and crowns followed over a 3- to 7-year period. MATERIAL AND METHODS: The study included 42 patients with a total of 51 FPDs and 12 single crowns assigned to 1 of 3 groups. The 3 groups comprised patients with abutment teeth with a questionable prognosis (n=10), advanced chronic periodontitis (n=19), or abutment teeth with a positive prognosis (n=13). The FPDs had a mean of 9.7 units (range of 3-14). Of the FPDs, 32 were provided with a cantilever on 1 side (n=24) or both sides (n=8). The mean observation time was 51 months (range of 28-82). All patients were examined by 2 independent prosthodontists using the California Dental Association (CDA) assessment system for evaluation. One-way ANOVA with Fisher's LSD post hoc test and the Mann-Whitney U test were used for statistical analyses (alpha=.05). RESULTS: Seventeen (34%) of the FPDs had biological and/or technical complications. Six (12%) FPDs were completely or partially removed during the observation period, 1 framework fractured, and 9 (17.6%) FPDs had ceramic fractures. Fifteen of the 21 fractured FPD units were related to FPDs that were placed in 3 patients with bruxing habits. The CDA rating for marginal integrity was "excellent" for more than 98% of the abutments. No patients reported adverse reactions to the material. CONCLUSIONS: Metal-ceramic FPDs made of cobalt-chromium alloy performed acceptably in the questionable prognosis and advanced chronic periodontitis groups.     

Comparison of factors potentially related to the occurrence of dental erosion in high- and low-erosion groups

Soft drink intake, method of drinking, pH variations, plaque topography, and various salivary, microbial and clinical factors were compared in Saudi men with high (n = 10, mean = 20.5 yr) and low (n = 9, mean = 20.3 yr) dental erosion. pH-measurements were carried out with a microtouch electrode at six different intraoral locations after the subjects had consumed 330 ml of regular cola-type drink in their customary manner. The results showed that higher intake of cola-type drinks was more common in the high- (253 l yr(-1)) than in the low-erosion group (140 l yr(-1)). High erosion was associated with a method of drinking whereby the drink was kept in the mouth for a longer period (71 s vs. 40 s). pH after drinking did not differ between the groups for any of the six measuring sites. Plaque accumulation on the palatal surfaces of maxillary anterior teeth and urea concentration in unstimulated saliva were lower in high-erosion subjects. Aside from these, there were no differences in salivary and microbial factors between the groups. First molar cuppings, buccal cervical defects, and mouth breathing were more common in the high- than in the low-erosion group. In summary, consumption of cola-type drink, method of drinking, amount of palatal plaque on anterior teeth, and salivary urea concentration are factors associated with dental erosion.     

Oxygen-dependent modulation of release and activity of polymorphonuclear leukocyte granule products

Polymorphonuclear leukocytes are important in the defense against the anaerobic microflora of infected gingival pockets. One part of this defense is release of antibacterial granule products by polymorphonuclear leukocytes into the pockets. The aim of the present study was to compare the efficiency of polymorphonuclear leukocytes in releasing granule products under aerobic and anaerobic conditions. Polymorphonuclear leukocytes were exposed to serum-opsonized zymosan under aerobic and anaerobic conditions. The levels of released granule products were determined by combining measurements of activity with enzyme-linked immunosorbent assays. The level of released elaslase was twice as high in anaerobic as in aerobic reaction mixtures. A similar difference was not detected for mycloperoxidase. However, mycloperoxidase was inactivated after its release under aerobic conditions. The release of lactoferrin was as efficient under aerobic as under anaerobic conditions. The effect of aerobic conditions on the release of elastase and the inactivation of myeloperoxidase could be ascribed to oxidants formed in the mycloperoxidase-H₂O₂-chloride system. Also, the activity of the released cytoplasmic enzyme lactate dehydrogenase was inactivated by oxidants formed in the myeloperoxidase-H₂O₂-chloride system. These findings suggest that, in the anaerobic environment of the gingival pocket, elastase and possibly also other azurophilic granule products are released in higher amounts than under fully oxygenated conditions. In this environment, the released products may also escape inaclivation by the myeloperoxidase- H₂O₂-chloride system.     

Galvanic currents between dental alloys in vitro

The galvanic current densities between gold, amalgam and cobalt-chromium, three different classes of dental alloys, were determined in vitro in artificial saliva kept at 35 degrees C. The maximum current density of 200 microA/dm2 was obtained between the conventional amalgam and a type III gold alloy. Galvanic currents of lesser magnitude could also be measured between amalgams high in copper and the other alloys. No measurable current densities were obtained between gold alloys and between gold and cobalt-chromium alloy with the exception of a casting and a solder gold alloy commonly used in combination.     

The incidence of a first major osteoporotic fracture in Iceland and implications for FRAX

Summary

Based on an extensive cohort study over 25 years, the present study supports the assumption that major osteoporotic fractures can be reasonably predicted from hip fracture rates.

Introduction

The construct for FRAX models depends on algorithms to adjust for double counting of fracture outcomes in some models and in others, to estimate the incidence of a major fracture from hip fracture rates. The aim of the present study was to test the validity of these algorithms in a large prospective cohort.

Methods

The incidence of hip, clinical spine, distal forearm, and humerus fracture was determined in the prospective and ongoing population-based Reykjavik Study with follow up of 257,001 person-years. The incidence of a first major fracture was compared with the correction factors used in FRAX to adjust the incidence of several fracture outcomes for double counting. In addition, the incidence of a major osteoporotic fracture estimated from the Icelandic hip fracture rates was compared with the Malmo ratios used in FRAX.

Results

The adjustments necessary to account for multiple fracture outcomes were similar to those previously derived from Sweden. Additionally, incidence of a first major osteoporotic fracture was similar to that derived for FRAX models.

Conclusion

The findings of the present study support the algorithms used in FRAX to estimate the incidence of a first major fracture and the predictive value of hip fracture for other major fractures.     

Perioperative blood transfusion does not decrease survival after surgical treatment of spinal metastases

Purpose

To assess whether perioperative allogenic blood transfusions in patients undergoing surgical treatment for spinal metastases independently influence patient survival.

Methods

A retrospective study including 170 consecutive patients undergoing surgical treatment for spinal metastases in 2009 and 2010 at a tertiary referral center. Variables related to postoperative survival were all included in the same multivariable logistic regression analysis with either 3- or 12-month survival as the dependent variable. The independent variables were: transfusion of allogenic red blood cells, age at surgery, gender, preoperative hemoglobin, revised Tokuhashi score and no. of instrumented levels.

Results

Perioperative allogenic blood transfusion of 1–2 units was associated with increased 12-month survival [p = 0.049, odds ratio 2.619 (confidence interval 1.004–6.831)], but not with 3-month survival. Larger transfusion volumes did not significantly influence survival.

Conclusion

The results of the present study support that perioperative blood transfusion of <5 units does not decrease survival in patients operated for spinal metastases. Transfusion of 1–2 units seems to be associated with increased 12-month survival. Future studies should assess if a liberal transfusion regime can be applied to this group of patients; thereby, prioritizing early postoperative mobilization.