Accuracy of a proposed implant impression technique using abutments and metal framework

PURPOSE: This study compared the accuracy of an abutment-framework (A-F) taken with open tray impression technique combining cementon crown abutments, a metal framework and resin cement to closed tray and resin-splinted open tray impression techniques for the 3-implant definitive casts. The effect of angulation on the accuracy of these 3 techniques was also evaluated. MATERIAL AND METHODS: Three definitive casts, each with 3 linearly positioned implant analogs at relative angulations 0, 30, and 40 degrees, were fabricated with passively fitted corresponding reference frameworks. Ten impressions were made and poured, using each of the 3 techniques on each of the 3 definitive casts. To record the vertical gap between reference frameworks and analogs in duplicate casts, a light microscope with image processing was used. Data were analyzed by two-way analysis of variance and the Tukey test. RESULTS: The open tray techniques showed significantly smaller vertical gaps compare to closed tray technique (P .05). CONCLUSION: The accuracy of the A-F impression technique was superior to that of conventional techniques, and was not affected by the angulation of the implants.

Comparative accuracy of new implant impression technique using abutments as impression copings with an angulated implant model / 대한치과보철학회지

STATEMENT OF PROBLEM: A new implant impression technique which use abutments as impression coping, and use resin cement as a splinting material was described. Accuracy of this technique was compared with conventional closed tray and resin splinted open tray technique for a 15degrees angled 3-implant model MATERIAL AND METHODS: A dental stone master model with 3 linearly positioned implant analogue and a reference framework which was passively fitted to it were fabricated. The center analogue was perpendicular to the plane of model and the outer analogues had a 15degrees angulation forward or backward. 10 closed tray impressions, 10 resin splinted open tray impressions, 10 abutment-resin framework cementation impressions and 10 abutment-metal framework cementation impressions were made with additional silicone material and poured with dental stone. A light microscope with image processing was used to record the vertical gap dimension between reference framework and analogue of duplicated cast made with each 4 impression techniques. Statistical analysis used one-way ANOVA with post-hoc tests Tukey test of .05 level of significance RESULTS: Significant difference in the vertical gap dimension was found between closed tray technique; 74.3 (+/-33.4)micrometer and resin splinted open tray technique, and two other new technique. (P>.05) Abutment-metal framework cementation technique;42.5 (+/-11.9)micrometer was significantly different from resin splinted open tray technique. (P.05) CONCLUSION: Within limitations of this study, the accuracy of implant level impressions of resin splinted open tray technique was superior to that of closed tray technique. A new technique using abutment and metal framework cementation was more accurate than resin splinted open tray technique.

The level of residual monomer in injection molded denture base materials / 대한치과보철학회지

STATEMENT OF PROBLEM: The residual monomer of denture base materials causes hypersensitivity on oral mucosa and intereferes with the mechanical properties of the cured resin. The amount of residual monomer is influenced by materials, curing cycle, processing method, and etc. PURPOSE: The aim of this study was to investigate the residual methyl methacrylate(MMA) content of injection molded denture base polymer, and to compare this with the self-cured resin and the conventional compression molded heat-cured resin. MATERIALS AND METHODS: Disc shaped test specimens (50mm in diameter and 3mm thick) were prepared in a conventional flasking technique with gypsum molding. One autopolymerized denture base resins (Vertex SC. Dentimex. Netherlands) and two heat-cured denture base resins (Vertex RS. Dentimex. Netherlands, Ivocap. Ivoclar Vivadent, USA) were used. The three types of specimens were processed according to the manufacturer's instruction. After polymerization, all specimens were stored in the dark at room emperature for 7 days. There were 10 specimens in each of the test groups. 3-mm twist drills were used to obtain the resin samples and 650mg of the drilled sample were collected for each estimation. Gas chromatography (Agillent 6890 Plus Gas Chromatograph, Agillent Co, USA) was used to determine the residual MMA content of 10 test specimens of each three types of polymer. RESULTS: The residual monomer content of injection molded denture base resins was 1.057+/- 0.141%. The residual monomer content of injection molded denture base resins was higher than that of compression molded heat cured resin (0.867+/-0.169%). However, there was no statistical significant difference between two groups (p > 0.01). The level of residual monomer in self cured resin(3.675+/-0.791) was higher than those of injection molded and compression molded heat cured resins (p<0.01). CONCLUSION: With respect to ISO specification pass/fail test (2.2% mass fraction) of residual monomer, injection molding technique(1.057+/-0.141%) is a clinicaly useful and safe technique in terms of residual monomer.