Dalkiz, Arslan, Tuncdemir, Bilgin, Aykul surface with finger pressure. Following trial clo- sures for removing excess resin, the flasks were closed, pressed and heated in a previously de- scribed manner. Preparation of specimens reinforced with rov- ing type glass fibers For specimen preparation of groups ROUND- ED/ROF, U/ROF and V/ROF containing roving type glass fibers (Vetrolex RC, 14-800-P-109, Ciba Composites, Birmingham, UK), fibers were cut 0.5 mm in length with a lancet. The fiber content was calculated from the initial weight of the specimens to an accuracy of 0.01 mg using a digital device (Mettler, Zurich, Switzerland).15 The weight of fi- bers was determined with a ratio of 10% by weight of the polymer matrix and impregnated with ap- propriate matching to polymer/monomer mixture. Prepared roving glass fibers were directly mixed with the polymer. The acrylic resin dough was prepared in a previously described manner and packed into the flask with finger pressure. Follow- ing trial closures for removing excess resin, the flasks were closed, pressed and heated in a previ- ously described manner. Measurement of interfacial distances Reference points A, B, C and D were marked as previously described onto each acrylic resin base specimen and distances between these reference points were measured to evaluate the probable linear dimensional change (Figure 2). Measure- ments were performed at these reference points using a metal gauge and a binocular stereo light microscope, under 20x magnification, 24 hours after the polymerization process. A second mea- surement was performed after the storage of the specimens in water for 30 days at room tempera- ture. Obtained data were recorded in millimeters. To determine the adaptation or the interfacial gap between acrylic resin bases and the stone casts after water storage, the specimens were sagittaly sectioned with a precision rotary micro- tome (Slee Cut, 6062, NIC Medikal, Izmir, Turkey) in an anteroposterior direction along the imagi- nary line passing between reference points A and D (Figure 2 and 3). A second frontal cross section - perpendicular to the sagittal section - was per- formed along a path passing between right and left first molar regions (Figure 2 and 3). To mea- sure the interfacial distance between the cast sur- face and the inner surface of acrylic resin bases, seven reference points were marked along the resin base/stone cast interface in sagittal sections and five reference points were marked at frontal cross sections (Figure 3). Measurements were performed at these reference points as previously described, 24 hours after the polymerization pro- cess. A second measurement was performed after the storage of the specimens in water for 30 days Figure 2. Linear distances between marked reference points A, B, C and D mea- Figure 3. Sagittal (a) and frontal (b) sections of test specimens and interfacial refer- sured with a metal gauge. ence points. Table 1. Main experimental groups representing palatal vault shapes and subgroups representing the fiber types used. (Vault shape) ROUND U-SHAPED V-SHAPED Subgroups (n=10) January 2012 - Vol.6 No fiber (NOF) ROUND/NOF U/NOF V/NOF Woven (WOF) ROUND/WOF U/WOF V/WOF Roving (ROF) ROUND/ROF U/ROF V/ROF 73 European Journal of Dentistry Total 30 30 30