Posterior bridges retained by resin-bonded cast metal inlay retainers: a report of 60 cases followed for 6 years

WOS: A1997XX62400010PubMed ID: 9357751Between May 1989 and July 1994, 60 adhesive fixed partial posterior dentures retained by resin-bonded cast metal inlays were placed under controlled conditions. The influence of prognostic factors on the event free and service duration was investigated with univariate and multivariate analysis. The majority of the failures (16 of 18) were caused by loss of adhesion at the metal cement interface and were observed either as debonding of the restorations completely or dislodgement of a single retainer. The other two failures appeared as secondary caries. Univariate analysis demonstrated that, retainer type, approximal configuration and dentine exposition had no effect on the event free service duration. On the other hand, gingival finishing level and luting agent were found to have an effect. Univariate testing was also conducted for the overall service duration and none of the variables were found to have an effect. Multivariate Cox Regression Analysis was performed to estimate the influence of categorical covariates: type of retainer, approximal preparation modification, gingival finishing level, preparation depth and luting agent on survival rates of event free and overall service duration. Luting agent was found to be the single independent prognostic variate (P < 0.0001) for the event free service duration and the other covariates were rejected. For overall service duration, none of the variables were found to be effective

In vitro comparison of cuspal fracture resistances of posterior teeth restored with various adhesive restorations

WOS: 000170122700014PubMed ID: 11508095Purpose: This study compared the cuspal fracture resistances of posterior teeth restored with five different adhesive restorations. Materials and Methods: Eighty-four sound human molars were included in this study. Sample molars were divided into seven groups. The first five groups received mesio-occlusodistal cavity preparations and were restored with (1) amalgam combined with urethane dimethacrylate cement, (2) posterior composite, (3) direct composite inlay, (4) cast-metal inlay, and (5) complete ceramic inlay. The sixth and seventh groups were introduced in the study as controls. Samples of group 6 were prepared but were tested without restoration (prepared-only group). Samples of group 7 were intact teeth and were tested as unprepared. All samples were loaded axially until failure. Results: While the unprepared teeth had a significantly higher resistance than all other groups, the prepared-only teeth were the weakest. No significant differences were found in resistance to cuspal fracture among the restoration groups. Conclusion: The difference between the mean cuspal fracture resistance of the unprepared and prepared-only groups was statistically significant. Restoration groups were stronger than the prepared-only group. However, differences between the restoration groups were insignificant

Modified flasking technique for processing a maxillary resection obturator with continuous pressure injection

WOS: 000172075200018PubMed ID: 11677541It is not possible for the wax pattern of most large-volume maxillary resection obturators to be placed into a flask for conventional compression molding processing and positioning of the wax pattern. However, these wax patterns and their channel access design often can be modified and aligned in position for processing with the continuous pressure injection technique. This article describes the use of the continuous pressure injection technique to process the perpendicularly aligned wax pattern of a maxillary resection obturator. It also describes a modified channel design and a simple method to pull back the injection funnel to increase the volume of the flask

Effect of different bonding agents on shear bond strengths of composite-bonded porcelain to enamel

WOS: 000182326200013PubMed ID: 12690353Statement of problem. The use of bonding agents in the luting procedure for porcelain laminate restorations to enamel is not clear. Purpose. This study evaluated the shear bond strength differences between an enamel-luting composite and a heat-pressed ceramic with 6 different bonding systems. Material and methods. Seventy standardized heat-pressed IPS Empress ceramic discs (4-mm diameter, 3-mm height) were prepared. A vertical planar enamel-bonding surface was prepared on the buccal or lingual enamel of 70 freshly extracted sound human molars and premolars. The teeth were oriented to maintain a parallel relationship between the bonding plane and the shear loading axis of a universal testing machine. Tooth specimens were divided into 7 groups (n = 10) comprising equal numbers of molars and premolars. The enamel surfaces of specimens in groups 1 through 6 were prepared with 1 of 6 bonding agents (Scotchbond Multi Purpose Plus, Heliobond, PQ1, SE Bond, Prime&Bond NT, and Prompt L-Pop). Finally, the specimens were luted to the ceramic discs with the composite cement (Opal Luting Composite). Ceramic discs in the seventh group (Control) were luted to the etched enamel with the composite cement without using bonding material. Enamel-ceramic specimens were kept in distilled water at room temperature for 30 days after cementation. All specimens were shear loaded axially in a universal testing machine with a crosshead speed of 0.05 mm/min until fracture. Shear bond strength was measured and recorded for each group in MPa. To determine the statistical significance of the differences between the mean shear bond strength values, a 1-way analysis of variance was used (alpha=.05). Post-hoc multiple comparisons were made with Duncan's multiple range analysis. Fractured surfaces of each specimen were also inspected with a stereomicroscope to evaluate failure modes. Results. A 1-way analysis of variance revealed significant differences between the test groups (P=.00). Bond strength values (MPa) from the highest to the lowest were as follows: Prompt L-Pop, 25.46 +/- 5.6; Prime&Bond NT, 18.99 +/- 4.93; Heliobond, 17.28 +/- 4.0; SE Bond, 16.21 +/- 2.6; PQ1, 15.60 +/- 2.8; Scotchbond MPP, 14.82 +/- 2.4; and Control, 10.55 +/- 1.6. Duncan's multiple range post hoc analysis exhibited significant differences between the control group and the adhesive bonding agent groups (P<.05). There were also significant differences between the bonding agent groups (P<.05). Prompt L-Pop showed the highest bond strength values. Conclusion. Within the limitations of this study, bonding agents appear to have a strengthening effect on the shear bond strengths of the enamel/composite/porcelain interface of the materials tested. Bonding agents used in this study showed similar bond strength values except for Prompt L-Pop, which demonstrated the highest bond strength values