A new method for fabrication of metal crowns has been developed by one of the authors (M.A.). There are two principles involved: machine duplication of models and electric discharge machining. The metal used is pure unalloyed titanium, which is processed as a coping and later covered by a composite resin. In 1986, 205 separate titanium crowns were made on 149 patients. One year later 192 crowns on 137 patients could be examined. Five crowns had been replaced by new ones owing to fracture of the composite resin. In accordance with the CDA quality evaluation system the following results were obtained for the remaining 187 crowns: margin integrity, 186 excellent or satisfactory (99.5%); anatomic form, 185 excellent or satisfactory (98.9%); and surface and color, 181 excellent or satisfactory results (96.8%). The 1-year results are promising, and further follow-up studies will be made.

No abstract

In 1986, 149 patients were provided with titanium crowns. The method used for fabrication of the titanium copings involved two principles: machine duplication of models and electric discharge machining. For the veneering of the copings, Isosit was used for the first 90% of the crowns in the series, and the Dentacolor-Silicoater technique for the last 10%. Of 205 individual crowns cemented in 1986, 167 could be examined after 2 years. The crowns were rated by four independent examiners using the CDA quality evaluation system. Bleeding Index and Margin Index were also used. The Margin Integrity score was recorded as satisfactory for all crowns examined over the period studied. A vast majority of the margins were rated as excellent. Isosit (n = 145) disclosed shortcomings including fractures and substantial deteriorations of Surface and Color and of Anatomic Form. With Dentacolor as veneering material (n = 18) the results with the factors Surface and Color and Anatomic Form were still rated satisfactory after 2 years, and no fractures of the veneering material were registered. Bleeding Index and Margin Index showed comparatively small changes after 2 years.

Bergman B, Ericson G: Cross-sectional study of padents treated with removable partial dentures with special reference to the caries situation. Scand J Dent Res 1986; 94: 436-42.Abstract -Thirty-four padents provided with removable partial dentures (RPDs) were reexamined after 3 yr. Garies that had developed during the period were analyzed with regard to the following potential caries risk factors: Lactobacilli, Streptococcus mutans, flow rate and buffer pH of paraffin stimulated saliva, oral hygiene and daily sucrose intake. Of 436 initially intact surfaces 31 (7.1%) had decayed and/or were restored during the 3-yr period. Caries recurred in 26 (6.2%) out of 422 initially restored surfaces during the same period. The development of new or recurrent caries had no correlation to whether or not the surfaces affected were in contact with the RPDs. No single caries risk factor seemed to he sufficiently closely correlated to the number of caries lesions developed to be used alone in the selection of patients at risk. When the sum of assumed negative factors was used a correlation was found for the group as a whole hetween the number of negative factors and the development of caries. However predicting the development of caries in any individual case seems to be more complicated.

– The caries situation among 30 patients with fixed partial dentures was examined 3 yr after cementation of the constructions. The fit of the crowns on the abutment teeth, the size of the interproximal areas and the relation between the crown margin and the gingival margin were registered. Risk factors for caries development, such as salivary factors, microbiologic factors, oral hygiene and diet were evaluated for each patient. During the 3‐yr period 54 caries lesions occurred in 25 patients. Eleven lesions were found on abutment teeth. Two were located on the root surfaces unconnected with the crown margin (>2mm from the gingival margin), three were recurrent lesions, where the crown margin was located above the gingival margin but closer than 2 mm and six were recurrent lesions where the crown margin was located under the gingival margin. No single caries risk factor seemed to be so closely correlated to the number of caries lesions developed that it could be used alone to select of patients at risk. When the sum of the assumed negative factors was used, more caries was found among the patients with three or more factors with negative values in the group as a whole. However, predicting the development of caries in an individual case with a high degree of probability seems to be complicated. Generally speaking there was no indication that caries disease development was caused by the presence of the fixed partial denture per se.