indiloy and tytin

The study aimed to validate the scoring of the degree of marginal degradation of amalgam restorations by using impressions, as an alternative to other indirect scoring methods using photographs or casts. Ten-year-old condensation silicone elastomer impressions and epoxy replicas made in 1979 were compared in a scanning electron microscope at 5 kV with different magnifications up to x200. The impression material was not distorted or degraded, and the dimensional stability was good after 10 years of storage in a dry environment. The inter-examiner agreement of the scorings of impressions and a six-point scale reference set was satisfactory as evaluated by kappa statistics, demonstrating that degrees of marginal degradation can be distinguished on impressions with relatively high accuracy. The rating distribution of the scorings of impressions showed good correlation to the rating distributions obtained with the clinical USPHS rating method and with photographs for recording marginal degradation. A slight difference between the photographic and impression ratings at the upper and lower levels of the six-point rating scale was observed. The difference varied with the type of alloy, possibly due to a bias depending on the surface quality--that is, whether the restoration kept the glossiness of high polishing or became heavily tarnished.

Topics: Dental Alloys; Dental Amalgam; Dental Impression Materials; Dental Restoration, Permanent; Dimethylpolysiloxanes; Epoxy Resins; Humans; Microscopy, Electron, Scanning; Models, Dental; Photography; Silicone Elastomers; Silicones; Surface Properties

The purpose of the study was to estimate the influence of different clinical variables on the replacement rate of class-II amalgam restorations in permanent teeth. The study included 210 patients who had 468 restorations placed by 7 Scandinavian dentists. The observation periods varied between 7 and 10 years. At the time of the last recording 188 restorations remained intact in 88 patients, whereas 68 restorations in 53 patients had been replaced. Eighty-six patients with 212 restorations had dropped out of the study. The most prevalent criteria for replacement were secondary caries (n = 30) and restoration bulk fractures (n = 24). Chi-square analyses of the relationship between the prevalence of replacements and the clinical variables indicated effects of the operator and the patients' age and caries activity (p less than 0.001). Similar results were observed when the functional time of the restorations was related to the clinical variables and analyzed by ANOVA and MCA analyses and by survival analyses using logrank and Wilcoxon tests (p less than 0.001). The survival analyses using the Lee-Desu statistic D showed in addition a slight difference between the restorations in the lower premolars and upper and lower molars. There were no differences in the clinical performance between four non-gamma-2 alloys and one conventional alloy. Furthermore, no differences were noted between the survival rates of MC, DO, and MOD restorations. In a Cox regression model the strongest effects on the estimated survival rates were associated with the patients' age and caries activity covariates (global chi-square = 23.5, df = 2, p less than 0.001), whereas the effects of the operator and the other clinical variables were insignificant.

Topics: Adolescent; Adult; Age Factors; Aged; Analysis of Variance; Chi-Square Distribution; Child; Cross-Sectional Studies; Dental Alloys; Dental Amalgam; Dental Caries; Dental Restoration, Permanent; Female; Humans; Life Tables; Longitudinal Studies; Male; Middle Aged; Recurrence; Regression Analysis; Reoperation; Surface Properties; Survival Analysis; Time Factors; Tooth Fractures

Mercury vapor release from amalgams during setting significantly decreases when the amalgams are prepared with binary Hg-In liquid alloys. The objective of this study was to compare the cytotoxicity of amalgams made with experimental Hg-In alloys with that of amalgam without In and a commercial In-containing amalgam.. Amalgam specimens were prepared by triturating a high-Cu alloy powder (Tytin, Kerr) with pure Hg or Hg-In liquid alloy containing 5, 20 or 50% In and also by triturating an In-containing high-copper alloy powder (Indiloy, Shofu) with pure Hg. After the specimens were aged for 2 wk, a cylindrical specimen of each amalgam was immersed consecutively in cell culture medium for 0-8, 8-48 and 48-72 h. The cytotoxicity of the extracts was determined by placing them in contact with Balb/c 3T3 mouse fibroblasts for 24 h, after which the succinic dehydrogenase (SDH) activity was measured and expressed as a percentage of the Teflon negative controls. The results were statistically compared using ANOVA and Tukey's test (alpha = 0.05). The concentration of elements released into the extracts was determined by atomic absorption spectrophotometry and evaluated by Kruskal-Wallis and nonparametric multiple comparisons.. For the 0-8 h and 8-48 h intervals, the 20% In amalgam was significantly (p < 0.05) less toxic than the other amalgams, and not different from the Teflon control. Results for the other amalgams were only slightly depressed compared to the Teflon control. For the 48-72 h interval, all amalgams were essentially no different from the control. Copper was the element dominantly released into the medium from all the amalgams tested.. For amalgam tested after aging, alloying indium to mercury did not deleteriously affect the cytotoxicity of the resultant amalgam compared to the amalgam without indium.

Topics: 3T3 Cells; Analysis of Variance; Animals; Copper; Dental Alloys; Dental Amalgam; Indium; Mercury; Mice; Mice, Inbred BALB C; Statistics, Nonparametric; Volatilization

This study examined the Hg evaporation behavior during the early setting of amalgams that contain In in the alloy powders. Two different types of commercially available In-containing alloys were tested: an In-particle admixed powder (Indisperse, D) and an In-containing single-composition powder (Indiloy, S). Mercury evaporation from specimens (4 mm in dia, 8 mm tall) was monitored 10 min after trituration to 180 min using a mercury vapor analyzer according to the methods used in a previous study. The amounts released from 10 min to 180 min were compared with the results of our previous study on a single-composition amalgam (Tytin, T) with pure Hg and with Hg-In liquids (5 or 10%). Amalgam S and In-containing T terminated Hg evaporation within 180 min. There was no significant (p > 0.05) difference in the amount released between T amalgam made using pure mercury and D, and between T amalgam made with 5% In-containing mercury and S amalgam. Mercury release from amalgam D was significantly (p < 0.05) higher than from S or both types of In-containing T amalgam. Adding In to mercury or alloying In into the alloy particles appeared to be more effective in reducing the mercury vapor than admixing pure In particles into the amalgam.

Topics: Analysis of Variance; Copper; Dental Alloys; Dental Amalgam; Indium; Mercury; Volatilization

The release of mercury vapor was determined from eleven different amalgams exposed to externally induced corrosion by galvanic contact with a dental casting gold alloy. The electrolyte was an artificial saliva solution at 37 degrees C. The corrosion rates of the amalgams could be divided into two groups corresponding to the grouping into conventional and high-copper materials. The mercury release rate decreased during the 24 h test period for all the amalgams except one containing indium. There was no significant difference in the total mercury release between the conventional and high-copper amalgams as groups. The same applied for the individual products, except the one containing indium, which released significantly more mercury vapor than the two products with the lowest release.

Topics: Analysis of Variance; Copper; Corrosion; Dental Alloys; Dental Amalgam; Electrogalvanism, Intraoral; Gold Alloys; Indium; Mercury; Silver; Statistics, Nonparametric

The effect of width of the restoration, tooth position, and amalgam type on the fracture of the margins of 13- to 14-year-old, high-copper, amalgam restorations was evaluated. The evaluation assessed 193 photographs of restorations by use of ridit analysis and a rank-ordering test. The results indicated that the width of the restoration was the predominant factor and that tooth position and the different high-copper alloys were less significant. Interactions between tooth position and width indicated that lower premolars with conservative restorations exhibited the least fracture at the margins, and upper premolars with a wide preparation exhibited the most. It is postulated that tooth deflection under mastication may play a role in long-term fracture at the margins of amalgams.

Topics: Analysis of Variance; Dental Alloys; Dental Amalgam; Dental Restoration, Permanent; Evaluation Studies as Topic; Humans; Odontometry; Risk Factors; Surface Properties

Fracture of the margins is the most common cause of failure of dental amalgam restorations. Both corrosion and creep have been identified as possible contributors to this type of failure. The stresses that induce creep may arise from the continued setting expansion of the amalgam, the formation of corrosion products, mastication, or from the thermal expansion of the amalgam during ingestion of hot foods. The latter two are low-frequency cyclic stresses. The amalgams used in dentistry have fusion temperatures only about 40 degrees C above mouth temperature, and they experience grain boundary sliding during creep deformation. Since grain boundary sliding, low-frequency cyclic stresses, and a temperature near the fusion temperature of the alloy are prerequisites for so-called "creep-fatigue fracture", this type of fracture may contribute to amalgam margin failure. Amalgam made from seven different alloys was condensed into stainless steel dies. After being allowed to set for seven days, the specimens were thermally cycled between 4 degrees C and 50 degrees C for 500 and 1000 cycles. Amalgam margin integrity was evaluated by scanning electron microscopy both before and after each cycling period. The amount of margin fracture was calculated after 1000 cycles. Thermal cycling of amalgam restorations placed in stainless steel dies resulted in predominantly intergranular fracturing of the amalgam margins, indicating that creep-fatigue failure may be a significant contributor to in vivo margin fracturing.

Topics: Chemical Phenomena; Chemistry, Physical; Dental Alloys; Dental Amalgam; Microscopy, Electron, Scanning; Stress, Mechanical; Surface Properties; Temperature