Which device is more accurate to determine the stability/mobility of dental implants? A human cadaver study.

Non-invasive devices including resonance frequency (RF) analysis and mobility measuring (MM) damping capacity assessment are used to measure implant stability/mobility. The aims of the study were to compare the primary stability of implant inserted into extraction sockets by using RF with cable, RF wireless and new wireless MM device, to clarify the relation between these devices and to understand the correlations between peri-implant bone levels and implant stability. A total of 30 screw-type implants (3.75 x 11 and 4.2 x 11 mm) were inserted into extraction sockets of eight mandibular pre-molar regions of human cadavers. The primary stability of implants was measured by three devices after insertion. Peri-implant vertical defects were created in millimetre increments ranging between 0 and 5 mm, and stability/mobility of implants were analysed. At placement, the mean implant stability quotient of RF with cable, RF wireless and MM device values was 46 +/- 1, 57.8 +/- 9 and -5.4 +/- 1, respectively. Statistical correlations were demonstrated between these devices (P = 0.001). Statistically significant differences were presented for all peri-implant detects ranging between 0 and 5 mm for RF with cable and RF wireless at all increments. However, only a significant decrease was found between 0 and 1 mm defects, and 4 and 5 mm defects in MM device. Although RF with cable and RF wireless seem to be suitable to detect peri-implant bone loss around implants in 1 mm increments, the new MM device may not be suitable to detect the 1 mm peri-implant bone changes in human dried cadaver mandibles.

Total antioxidant levels of saliva in children related to caries, age, and gender.

AIM: The purpose of this study was to evaluate the relationship between the physicochemical properties of saliva such as flow rate, buffering capacity, pH, calcium level, total protein, total antioxidant status, and dental caries, age, and gender. MATERIAL AND METHODS: The antioxidant activity of saliva was investigated in 80 healthy children aged 7-15 years. They were divided into subgroups according to gender, age (7-10 years and 11-15 years), and caries activity (caries active=CA and caries free=CF). Unstimulated saliva samples were collected from all groups. Flow rates were determined, and samples analysed for pH, buffer capacity, calcium, total proteins, and total antioxidant status. Salivary total antioxidant activity (TAA) was estimated by an adaptation of the ABTS (2,2-azino-di (3-ethylbenzthiazoline-6-sulphonate)) assay. RESULTS: The results indicated that in general, although there was no linear association between salivary flow rate pH and buffering capacity values obtained from different groups, salivary calcium concentration values were found to be higher in caries free groups. Total protein and total antioxidant values were higher in caries active groups except those in the 11- to 15-year-old girls group. CONCLUSION: In general, total protein and total antioxidant insaliva were increased with caries activity. Calcium concentrations in saliva were higher in caries-free children. In addition, calcium concentration increased with age. Thus, it can be concluded that a linear association exists between calcium concentration age and caries activity. More clinical and laboratory studies are needed to determine the exact relationship between the physicochemical properties of saliva such as flow rate, buffering capacity, pH, calcium level, total protein, total antioxidant status, and dental caries, age, and gender.

Penetration of radiocalcium at the margins of resin and glass ionomer dentine bonding agents in primary and permanent teeth.

OBJECTIVES: The purpose of this study was to compare the leakage of three resin dentine bonding agents (Prime and Bond, Scotchbond Multi-Purpose, Probond) and a glass ionomer dentine bonding agent (GC Fujibond LC), in cervical cavities prepared in primary and permanent molar teeth restored with a hybrid composite resin (Tetric). METHODS: Cervical cavities without a bevel at the cavo-surface margins were prepared in the buccal and lingual surfaces of extracted primary and permanent molar teeth. After being restored, the teeth were stored for 1 week in a saline solution at 37 degrees C and then thermally cycled between 5 and 55 degrees C. Marginal leakage was determined subsequently using a radioactive isotope containing 45Ca and an autoradiographic technique. RESULTS: The results revealed that there were no statistically significant differences in microleakage of the bond between permanent and primary teeth dentine and Fuji Bond LC and Probond dentine bonding agents. The difference between permanent and primary teeth groups for gingival values of the Prime and Bond 2.1 group U=22.5, p=0.0355 and the Scotchbond Multipurpose group U=24.0, p=0.0406 were statistically significant. There were no significant differences between the occlusal and gingival microleakage values in either primary or permanent teeth with Prime and Bond 2.1, Fuji Bond LC and Probond except the difference at Scotchbond Multipurpose in primary teeth. For primary teeth gingival margins, none of the bonding systems were significantly different from the control group. CONCLUSIONS: These results indicate that although no statistically significant differences were found between test and control group values, the use of Fuji II LC in cervical cavities with cementum margins in primary teeth would provide the best resistance to microleakage among the test materials while the use of Scotchbond Multi-Purpose would provide the best resistance to microleakage in cervical cavities with cementum margins in permanent teeth.

Resin shear bond strength to porcelain and a base metal alloy using two polymerization schemes.

STATEMENT OF PROBLEM: Fractures in ceramometal restorations can occur and need to be repaired because replacements are not an economic solution. PURPOSE: This study evaluated the shear bond strengths of 4 porcelain repair systems (Metabond C&B [ME], Silistor [SI], Clearfil Lustre [CL], and Scotchbond Multipurpose Plus [SQ]) to a base metal alloy and porcelain in relation with the polymerization shrinkage of a visible light-cured composite superstructure and compared with the ceramometal bond strength (Vita VMK 68). MATERIAL AND METHODS: Thirty-two samples were prepared for each bonding system: 16 for resin-metal bond strength test, and 16 for resin-porcelain bond strength test. For each group, bonding agent was applied to 8 substructures and the resin superstructure was polymerized onto the bonding agent; and for the remaining 8 specimens, prepolymerized resin superstructures were bonded with bonding agent. All specimens were subjected to 500 cycles between 5 degrees C and 55 degrees C with 20 seconds dwell time. Tests were performed in a mechanical testing machine with a 0.5 mm/min crosshead speed. RESULTS: All materials showed an increase in shear bond strength when prepolymerized resin superstructures were used. However, the effect of polymerization shrinkage of resin superstructure was statistically significant only for CL group (P <. 05). The highest metal-resin bond was obtained from ME group with prepolymerized resin superstructures (35.27 +/- 2.40 MPa), and the lowest value was obtained for the SI group in which resin superstructures were polymerized in situ (8.71 +/- 1.03 MPa). The highest porcelain-resin bond was obtained from SC group with prepolymerized resin superstructures (20.71 +/- 1.13 MPa) and the lowest was obtained from SI group (9.99 +/- 1.52 MPa). CONCLUSION: Higher bond strength values were obtained with prepolymerized resin superstructures compared to in situ polymerized superstructures. Metabond C&B provided the best results for both prepolymerized and in situ polymerized resin superstructure preparation techniques at the failures where metal was exposed. The best results in situations in which the fracture is limited into porcelain were obtained with the use of Scotchbond Multipurpose Plus material. However, a variety of in vivo and in vitro tests are required before a final judgment is made.

Evaluation of colour and hardness changes of soft lining materials in food colorant solutions.

The aim of this study was to measure the colour stability and viscoelastic properties of three commercially available soft lining materials in vitro, by exposing them to 3% erythrosine, tartrazine and sunset yellow solutions. The colour changes were determined using a computer controlled spectrophotometer. The colour change of three soft lining materials--Molloplast B, Flexor and Coe Super Soft--were determined after 1, 3 and 6 months storage in three different food colorant solutions. The colour changes of Molloplast B was not noticeable. Only the initial colour value of Flexor was significantly different from the other time interval colour measurements. On the other hand, the colour difference of Coe Super Soft was found to be significantly different at all comparative time interval measurements (P<0.05). According to Shore A hardness values, Molloplast B had an initial hardness of 44 in all three solutions, and there was a slight increase after 6 months. Flexor had an initial hardness of 39, at the end of 6 months the hardness changed a little. Coe Super Soft was fairly hard after processing and Shore A hardness was initially 89 which increased to 95 later on. According to these results, only the hardness values of Coe Super Soft showed a statistically significant difference when compared using Wilcoxon signed rank test at the P<0.05 level. As a conclusion, silicon type soft lining material seems to be more resistant to colour change and hardness than the acrylic type soft liners.

Tensile strength and microleakage of the bond between a nickel-chromium alloy and a visible light-cured resin composite: effect of 4-META, silicoating, and bead retention.

Three retention systems, 4-META adhesive, Silicoating, and a conventional retention beads system, were used for resin-metal bonding. For each group, 40 standard specimens were prepared (20 for microleakage testing and 20 for tensile strength testing). Wax patterns were prepared, invested, and cast with a nickel-chromium alloy. The metal surfaces of the specimens were sandblasted with 250-microns aluminum oxide. Dentacolor Opaque was placed and set in a light curing unit for 90 seconds. Dentacolor resin composite was placed and set in the same unit for 90 seconds. The bonded specimens were subjected to thermocycling process in baths of 5 degrees C and 55 degrees C with 30-second dwell time. The tensile strength test specimens were stored in water, and the microleakage test specimens were stored in 5% basic fuchsin dye for 2 days. The means of the tensile strength test groups were not significantly different. However, the differences in microleakage among groups were found to be statistically significant. As a result, 4-META and Silicoating systems were found to be better than the conventional retention beads system, which allowed the greatest microleakage.

Effect of 4-META adhesive on the bond strength of different metal framework designs and acrylic resins.

The effect of relining the 4-META adhesive resin onto metal alloy of a partial denture framework was tested. Seventy-two metal frameworks with three different retentive patterns were designed. Half of the specimens were treated with 4-META, the other group was left untreated. Thirty-six specimens were first divided into three groups in which 12 samples had different designs of retention, i.e. mesh, ring-shaped and flat plane. Then, each different retentive design was divided into two groups and in one group Lucitone 199 and the other QC acrylic resin were processed. Finally they were subjected to shear test. While samples with adhesive exhibited greater bond strength than the others, samples without adhesive may be ranked in the order mesh, ring-shaped and flat planes with regard to shear bond strength. In samples with adhesive, the flat plane ones displayed better results. Statistically significant differences were observed in the relationships between the groups.