The International Journal of Prosthodontics, 05/1996

The design and engineering characteristics of the Spline dental implant were investigated. Compressive strength were evaluated. The results of the mechanical test indicated that this implant/abutment complex is mechanically stable, has minimal rotational movement, improved resistance to screw loosening, and good interface fidelity. The data for the new design are compared with published data for other implant/abutment connections.

The failure stresses in flexural tests of a densely sintered high-purity alumina (Procera AllCeram) were evaluated using three-point bend, ring-on-ring, and piston-on-three-ball tests. Glass-infiltrated presintered alumina (In-Ceram) and leucite-reinforced porcelain (IPS Empress) disks with the same dimensions were also tested using ring-on-ring and piston-on-three-ball tests. The failure stresses for all materials were substantially different (up to 50%) with different testing methods, and cannot be directly compared. However, by considering the effective specimen area under the maximum tensile stress, thes e failure stress data could be compared. The results emphasize the importance of knowing the test method and the method of calculation when comparing data. These three testing methods were also subjected to Weibull analysis. The Procera AllCeram had a consistently higher failure stress than the other two materials.

Progressive systemic sclerosis, or systemic scleroderma, is an autoimmune multisystemic disease associated with vascular abnormalities, connective tissue sclerosis, atrophy, and autoimmune changes. The complex oral problems that may develop in patients with the disease and the difficult oral access necessitate extreme care in preventing d ental disease. The oral management of a patient with an edentulous mandible and progressive systemic sclerosis, using an overdenture supported by osseointegrated implants, is presented and discussed.

This in vitro study examined the effect of cement volume on the seating of complete crowns. A spaced complete crown was made to fit a nickel-chromium replica mounted in a cementation jig that allowed static and dynamic seating. The crown was luted 10 times for each group using zinc phosphate cement under an initial static load followed by a dynamic load of 1,500 Hz. Seating was measured by a linear variable differential transducer. Mean vertical discrepancies for the three cement volumes were: completely filled (90.0 ± 15.2 um); half filled (42.1 ± 8.6 um); and brushed on (27.4 ± 7.2 um). Means differed significantly (P .0005). This study indicated that a thinly brushed-on layer of luting cement gave smaller vertical seating discrepancies than greater volumes of luting cement.

The surface roughness of Vita VMK porcelain following oven glazing and eight grinding/polishing treatments was analyzed qualitatively using scanning electron microscopy and quantitatively using a profilometer. Techniques were selected to simulate clinical practice. Scanning electron microscopy evaluation found oven glazing produced a better surface than other polishing methods. On the basis of the profilometric examination, the best roughness average value was obtained using diamond instruments with progressively smaller particle sizes (30, 15, and 8 um). Scanning electron microscopy analysis showed that all the treatments left the surfaces partially prous and cracked; however, the glazed surface yielded the best result. Although no significant differences were detected for the different treatments, the use of a 30-um diamond instrument pr oduced a rougher surface. No correlation was found between scanning electron microscopy and profilometer results. This study suggests that several procedures may be used to effectively finish ceramic surface

This study compared plaque accumulation on glazed and nonglaze d metal ceramic porcelain surfaces with shaded and nonshaded Dicor cast ceramic surfaces. plaque accumulation on natural teeth was also measured at 4, 12, 24, and 48 hours. Bacterial cultures were prepared from each sample to establish the aerobic and anaerobic charge. Plaque accumulation between 12 and 24 hours was measured on different materials. No significant differences were discovered between the plaque-retaining capacities of metal ceramic porcelain and Dicor ceramic surfaces. There was less plaque accumulation on glazed surfaces than on nonglazed surfaces.

This study compared the superficial tissue responses to titanium and ceramic surfaces of transmucosal elements of established IMZ implants. In a split-mouth study on 14 patients with two mandibular implants and a bar-retained complete mandibular denture, a conventional titanium and a newly developed ceramic-coated transmucosal element were placed. A range of clinical parameters were recorded before transmucosal-element replacement and at 1, 4, and 12 we eks postplacement. A comparison of the recorded soft tissue responses revealed no significant differences between a group of implants fitted with ceramic-coated transmucosal elements and a group of contralateral implants fitted with titanium transmucosal elements. Further analysis suggested that the peri-implant soft tissues adjacent to titanium and ceramic surfaces may differe in features that are not apparent when routine clinical parameters are used. The plaque accumulation scores for ceramic-coated transmucosal elements were significantly lower than those recorded in titanium transmucosal elements. These results suggest that the further development of a ceramic implant transmucosal collar may assist plaque control at the soft tissue-implant interface and may favourably influence the tissues in this region. This investigation should be considered a pilot study in view of the duration of the observations and a number of patients involved.

The successful rehabilitation of a patient with severe vertical overlap resulting from the loss of posterior occlusal support and excessive wear of the mandibular incisors is described. The treatment plan necessitated extraction of the remaining periodontally compromised mandibular teeth and placement of eight implants. Lost occlusal vertical dimension and morphologic facial height were restored using a fixed detachable implant-supported mandibular prosthesis, and the maxillomandibular relationship was transformed from Class Ii to Class I.

This cross-sectional study examined the strength of association between systemic osteoporosis and periodontal status in postmenopausal non-Hispanic white women. Twenty subjects with low bone density and a spine bone density of 0.753 ± 0.039 dual-energy x-ray absorptiometry units (g/cm2) and 22 subjects with high bone density and a spine bone density of 1.032 ± 0.028 dual-energy x-ray absorptiometry units )g/cm2) were randomly selected from a cohort of 565 women. Periodontal assessment included Plaque Index, Gingival Index, pocket depth, gingival recession, and periodontal attachment level. There were no significant differences in Plaque Index, Gingival Index, and probing depth in both groups; however, there were significant differences in gingival recession components of pe riodontal attachment level in both groups. This study suggests that systemic osteoporosis may contribute to periodontal attachment loss in the form of gingival recession.

The retention in root canals of serrated carbon fibre Composiposts and stainless steel Paraposts was tested under tensile load. Twenty unrestored human roots were endodontically prepared and root filled. Two groups of 10 roots received 1.4-mm Composiposts or 1.25-mm Paraposts luted with a resin cement. The specimens were then embedded in acrylic resin and mounted in an Instron machine. The tensile force (kg) required to dislodge the posts was recorded and analysed with Student's t test. The results revelaed that there was no significant difference in the retention of either post (P .05). The rigidity of 10 1.4-mm serrated Composiposts was tested in a three-point bend test in an Instron machine, and the retention of composite cores to 10 of these posts under tensile force was also tested. The results from these tests were compared to previous data from the authors' laboratory and revealed that the serrations significantly reduced the rigidity of the post (P .001) and increased the retention of a core material (P .001).