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Objectives: The purpose of this in vitro study is to compare the compressive strength (CS) and diametral tensile strength (DTS) of the zirconia-reinforced restorative material (Zirconomer®) with conventional glass ionomers (Fuji 1X) and amalgam., Materials and Methods: Specimens (n = 120) were fabricated from silver amalgam, reinforced glass ionomer cement (GIC) (glass ionomer, Fuji 1X GC Corp.), and zirconia-reinforced glass ionomer (Zirconomer, Shofu Inc.) for testing the CS and DTS. The results were analyzed using analysis of variance, followed by a Tukey post hoc test., Results: Both CS and DTS were found to be significantly higher for the zirconia-reinforced GIC and silver amalgam compared with GIC (p < 0.001)., Conclusion: A newer class of restorative material like Zirconomer helps to overcome the potential hazard of mercury, but retains the strength and durability of amalgam as well as the sustained high-fluoride release of GICs. Furthermore, long-term studies are required to confirm its use as an alternative to the currently available posterior restorative material.

Purpose: This study evaluated the retention of dental post heads (No. 2 Flexi-Post) embedded in 5 core materials (1 automix resin composite, 2 hand-mixed resin composites, and 2 glass ionomers)., Materials and Methods: Samples were prepared by embedding post heads in 4.5-mm-thick disks of core material., Results: The resin composite materials provided significantly more retention than the glass-ionomer-based materials. The post head retention of the automix resin composite was comparable to that of the hand-mixed resin composites., Conclusion: Unlike the resin composite samples, all the glass-ionomer samples fractured during testing. This is an unacceptable condition for a clinically successful restoration.

Objectives: The purpose of this study was to evaluate the clinical performance of two adhesively retained composite core materials and compare them with a metal-added glass ionomer. The main objective evaluated was total or partial loss of build-ups during the treatment prior to crown cementation., Methods: In 187 patients, 315 vital and non-vital teeth were built up after randomisation with either Rebilda D (RD), Rebilda SC (RSC) or Ketac Silver Aplicap (KSA). The composites were applied in the total-etch-technique with the corresponding dentin bonding agent. The metal-added glass ionomer was used with a conditioner. One group of patients was treated by experienced dentists, the other by dental students, in order to evaluate the effects of different levels of experience. Data were analysed using Mann-Whitney-U-Test and binomial logistic regression., Results: The early failure rate (partial or total loss) of core build-ups before crown cementation was significantly higher for KSA (28.8%), as compared to RSC (15.3%, p=0.037) and RD (15%, p=0.025). Most failures were observed during the removal of the temporary crowns. The rate of replacements was between 3.0 (RD/dentists) and 20.4% (KSA/students). Furthermore, we found that build-ups made by students had a significantly higher risk of loss than those made by dentists (p=0.028)., Conclusions: Adhesively retained self-curing composites show a better clinical short-term performance and can be recommended as core build-up materials.

Objectives: Glass ionomer cements (GIC) have been modified in an attempt to improve their mechanical properties. The objective of the present paper was to compare the two-body and three-body wear of four modified GIC. The tested materials were Fuji IX (GC Corporation), Hi-Fi (Shofu) and Ketac Molar Aplicap (3M/ESPE). The cermet cement Ketac Silver Maxicap (3M/ESPE) was used as reference material., Methods: Two-body wear tests were carried out in the computer controlled 'artificial mouth' of the Munich Dental School, three-body wear was tested with the ACTA wear machine., Results: The resulting average two-body wear rates (in microm) were: Fuji IX 327 (SD +/- 82) < Ketac Molar 379 (SD +/- 94) < Hi-Fi 376 (SD +/- 90) < Ketac silver 449 (SD +/- 127). The differences between the materials were significant (P < 0.05, ANOVA, modified LSD-test) with the exception of Ketac Molar and Hi-Fi. The average three-body wear rates (in microm) were: Hi-Fi 30 (SD +/- 10) < Ketac Molar +/- 42 (SD +/- 12) < Fuji IX 49 (SD +/- 14) < Ketac silver 73 (SD +/- 23). The difference between Ketac silver and the three other materials was significant (P < 0.05, ANOVA, modified LSD-test). No significant difference was calculated between Hi-Fi, Ketac Molar and Fuji IX., Conclusions: As Ketac Molar, Hi-Fi and Fuji IX show better wear resistance compared to Ketac silver both in occlusal-contact and contact-free areas, it may be assumed that the wear resistance of a glass ionomer cement may be improved more by changing the powder: liquid ratio than by incorporating silver particles into the glass powder.

Objectives: Conventional and resin-modified glass-ionomer cements (GIC, RM-GIC) are available for clinical use as restorative materials or as liners and bases. This study was conducted to compare the effect of a 12-month storage period in water on the surface microhardness, measured in Vickers units (VH), between a GIC and a RM-GIC group and to determine if the addition of resins improved the GIC microhardness., Method: VH microhardness was assessed in three GIC: Ketac-Fil, Ketac-Molar and Ketac-Silver (KF, KM, KS) and three RM-GIC: Photac-Fil, Fuji II LC and Vitremer (PF, FU, VI) stored in distilled water at 37 degrees C for 12 months. Measurements were taken at 1, 7, 15, 30, 90, 180 and 365 days. The statistical evaluation was done by means of one-way analysis of variance (ANOVA) and Tukey's multiple comparison tests., Results: There are significant VH differences among the materials studied and within each material over storage time. GICs, except for KS, showed a higher VH throughout the study period. Among the RM-GIC, VI showed a significantly higher VH at 12 months than at 1 day. The VH of PF diminished in the final stage of the study, whereas that of FU stabilized., Significance: The results suggest that the addition of resins to the GIC did not appear to improve the surface microhardness of these materials. Furthermore, the surface microhardness of both the conventional and resin-modified glass-ionomers suffered variations over time. However, these materials should not be deemed inadequate for use in clinical applications. Probably, conventional and resin-modified GICs placed in the oral environment would not be affected to the same extent as in in vitro tests.

Objective: To compare the clinical and radiographic treatment outcome of retrograde root filling with either dentin-bonded resin composite (Retroplast, RP) or glass ionomer cement (Chelon-Silver, CS)., Study Design: A prospective, randomized clinical study of 134 consecutive patients with indication of retrograde root filling of an incisor, canine, premolar, or first molar. Either RP or CS was chosen at random as retrograde filling material. Either material was applied onto the entire resection surface after prepared slightly concave. This preparation technique makes a sealing of the entire resection surface possible and prevents marginal contraction gaps during polymerization. A total of 122 patients were available for 1-year follow-up., Results: After 1 year the proportion of successful cases was significantly higher in the RP group (73%) than in the CS group (31%) (p<0.001). Doubtful healing with a need for a longer observation period was seen in 17% of the RP cases and 19% of the CS cases. The proportion of failures in the RP group (10%) was significantly lower than that in the CS group (50%) (p<0.001). Most of the unsuccessful CS cases failed due to loosening of the retrograde filling., Conclusions: Dentin-bonded RP applied onto the entire, slightly concave resection surface is a predictable apical sealant characterized by a high success rate. In contrast, retrograde root filling with CS results in an unacceptably high failure rate due to insufficient bonding strength to the concave resection surface.

Statement of Problem: New glass ionomer cements exhibit better mechanical properties than their older counterparts. However, there is concern about their use as a core material in post-and-core applications., Purpose: This in vitro study evaluated the fatigue resistance of 2 new glass ionomer cements, Shofu Hi-Dense and Fuji IX GP, and compared their mechanical behavior as a core material under masticatory load with a silver-reinforced glass ionomer (ESPE Ketac-Silver) and a silver amalgam (Cavex Avaloy LC)., Material and Methods: A total of 100 commercial plastic teeth were divided into 4 groups of 25 specimens each. Titanium posts were placed in the prepared root canals, and cores were built up in amalgam, silver-reinforced glass ionomer cement, and the 2 new glass ionomer cements. The post-and-core specimens were prepared for full cast metal crowns, which were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator and cyclically loaded with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. The specimens were sectioned and observed macroscopically and microscopically to determine the number of defects (alterations) in each material. Observed defects were verified with the Kruskal-Wallis test, and the 4 core materials were ranked with the Tukey multiple comparisons test., Results: The mean rank sum values of the defects were as follows: Cavex Avaloy LC Amalgam (16.75), Fuji IX GP (38.50), Shofu Hi-Dense (39.53), and ESPE Ketac-Silver (67.22). The amalgam alloy was significantly different (P< .05) from the others., Conclusion: Under the conditions of this study, the 2 new glass ionomer cements used as core materials showed a higher number of defects than amalgam. These results suggest that their fatigue resistance may be inadequate for post-and-core applications.

This study investigated the wear resistance of three restorative reinforced glass ionomer cements (Fuji IX GP FAST [FJ], Miracle Mix [MM] and Ketac Silver [KS]). Microfilled (Silux [SX]) and mini-filled (Z100 [ZO]) composites were used for comparison. Six specimens were made for each material. The specimens were conditioned for one week in distilled water at 37 degrees C and subjected to wear testing at 20 MPa contact stress against SS304 counterbodies using a reciprocal compression-sliding wear instrumentation. Distilled water was used as lubricant. Wear depth (microm) was measured using profilometry every 2,000 cycles up to 10,000 cycles. Results were analyzed using ANOVA/Scheffe's test (p<0.05). After 10,000 cycles of wear testing, ranking was as follows: KS>ZO>MM>FJ>SX. Wear ranged from 26.1 microm for SX to 71.5 microm for KS. The wear resistance of KS was significantly lower than FJ, MM and SX at all wear intervals. Although KS had significantly more wear than ZO at 2,000 to 6,000 cycles, no significant difference in wear was observed between these two materials at 8,000 and 10,000 cycles. Sintering of silver particles to glass ionomer cement (KS) did not appear to improve wear resistance. The simple addition of amalgam alloy to glass ionomer may improve wear resistance but results in poor aesthetics (silver-black color). FJ, which relies on improved chemistry instead of metal fillers, showed comparable wear resistance to the composites evaluated and is tooth-colored. It may serve as a potential substitute for composites in low-stress situations where fluoride release is desirable and aesthetic requirements are not high.

Objective: Aim of the present study was to evaluate the clinical suitability of the condensable metal-reinforced glass ionomer cement Hi-Dense in classes I and II cavities of primary molars., Methods: Seventeen children received a total of fifty four Hi-Dense fillings (nineteen class I and thirty five class II). The restorations were clinically assessed at baseline, after one and after two years of clinical service according to modified USPHS codes and criteria. The restorations were replicated in each recall and representative samples were qualitatively analysed under a SEM., Results: Over the observation period of two years, five restorations failed due to total retention loss, two fillings needed replacement because of persisting hypersensitivity, one filling was lost because of an unsuccessful endodontic treatment, and four restorations remained intact until natural exfoliation (Two year survival rate: 92% for Class I and 66% for Class II). The SEM analysis of surfaces and marginal areas exhibited an inferior adhesive performance primarily in proximal areas, whereas a negative step formation due to wear was frequently observed in occlusal parts., Conclusions: The results clearly indicate that the condensable, metal-reinforced GIC Hi-Dense reveals no enhanced performance and lifetime expectancy for class II restorations in primary molars when compared to other non-resin-modified GICs.

Statement of Problem: Strength greatly influences the selection of core materials. Many disparate material types are now recommended for use as cores. Cores must withstand forces due to mastication and parafunction for many years., Purpose: This study compared the compressive and diametral tensile strengths of 8 core materials of various material classes and formulations (light-cured hybrid composite, autocured titanium containing composite, amalgam, glass ionomer, glass ionomer cermet, resin-modified glass ionomer, and polyurethane)., Material and Methods: Materials were manipulated according to manufacturers' instructions for use as cores. Mean compressive and diametral strengths with associated standard errors were calculated for each material (n = 10). Analyses of variance were computed (P <.0001) and multiple comparisons tests discerned many differences among materials., Results: Compressive strengths varied widely from 61.1 MPa for a polyurethane to 250 MPa for a resin composite. Diametral tensile strengths ranged widely from 18.3 MPa for a glass ionomer cermet to 55.1 MPa for a resin composite. Some resin composites had compressive and tensile strengths equal to those of amalgam., Conclusion: Light-cured hybrid resin composites were stronger than autocured titanium containing composites. The strengths of glass ionomer-based materials and of a polyurethane material were considerably lower than for resin composites or amalgam.

Objective: To compare a silver-reinforced glass ionomer material (cermet) with a resin-modified glass ionomer in minimal Class II preparations in primary teeth., Methods: Matched pairs of primary molars with approximal caries that required operative treatment were used. Each cavity was filled with either Vitremer or Ketac-Silver. The restorations were followed for at least 36 months and examined annually using bitewing radiographs and clinical inspections. Impressions were taken at each recall and models were examined microscopically., Results: After 36 months, one of the resin-modified glass ionomer (RMGI) restorations and 13 (26.5%) of the silver cermet restorations had failed. The RMGI failed because of secondary caries, while most of the failures of the silver cermet fillings were marginal defects alone or in combination with secondary caries. The median survival time (MST) for the silver cermet restorations was 37 months. The RMGI restorations had a MST exceeding 42 months, but MST could not be calculated exactly because of the low failure rate during the study period., Conclusions: The resin-modified glass ionomer had the overall best performance of the two materials under comparison. The silver cermet material cannot be recommended for Class II restorations in primary teeth.

Silver amalgam has become a less attractive dental restorative material for restoration of primary teeth. After many decades of scientific and nonscientific controversy, use of silver amalgam for primary teeth is waning, not because of its mercury content but because dentistry has come up with more suitable materials. This article reviews the development and use of glass-ionomer silver-cermet cements, resin-modified glass-ionomer cements, and polyacid-modified resin composites (compomers) for restoration of primary teeth.

The purpose of this in vitro study was to evaluate the influence of conditioners on the enamel and dentine margin sealing ability of three different reinforced glass-ionomer cements. Two Class V preparations were made on the buccal and lingual surfaces of 36 freshly extracted molar teeth. Preparations were solely in enamel or dentine/cementum. The teeth were randomly divided into three groups of 12 and restored with either Ketac Silver (KS), Hi-Dense (HD) or Miracle-Mix (MM) with and without (-C) their respective conditioners. All materials were capsulated and were manipulated according to the manufacturers' instructions. The restorations were finished as recommended by the manufacturers and then stored in saline at 37 degrees C for 1 week, polished, thermally stressed, subjected to dye penetration, sectioned and scored. Rankings in the order of decreasing leakage were as follows: enamel margin KS > KS-C > HD-C > HD > MM > MM-C; dentine margin KS > HD-C > KS-C > HD > MM-C > MM. At the enamel margins, only HD showed a significant increase in leakage when conditioner was not used. At the dentine margin, however, KS had significantly more leakage than KS-C and HD-C had significantly more leakage than HD. There was no significant difference in leakage for MM both with and without conditioner. The influence of conditioners on marginal leakage appears to be both product and tissue specific.

This in vitro study evaluated the amount of fluoride released from fluoride-containing materials over a period of 28 days. Six disk samples (2.06 +/- 0.06 cm2) were prepared of each material and divided at random into seven groups: Group 1: Chelon-Fil; Group 2: Chelon-Silver; Group 3: VariGlass; Group 4: Dyract; Group 5: Vitremer; Group 6: Vitremer + Scotchbond Multi-Purpose; Group 7: Fuji II LC. The cements were mixed according to the manufacturers' recommendations, placed in plastic molds, and pressed between two glass plates. Paraffined dental floss was incorporated into the cements during setting to serve as attachments. The materials in Groups 3, 4, and 5 were light cured (Heliolux) in two different positions for 40 seconds each. In Group 6, the adhesive was light cured in two different positions on both sides for 10 seconds each. The samples were stored at 100% relative humidity for 24 hours. Each sample was then suspended in individual plastic tubes containing 5 ml of deionized water and submitted to constant agitation at 25 degrees C. The water was changed every 24 hours. Fluoride release was determined at 1, 2, 3, 4, 5, 7, 14, and 28 days after buffering the solution with equal volume of TISAB. Fluoride release was measured with a fluoride ion-specific electrode (Orion 96-09) and an ionanalyzer (Orion EA 940) previously calibrated with standard solutions containing 0.05 to 5.00 micrograms F/ml. Fluoride release was expressed as ppm in solution and micrograms F/cm2. ANOVA and Student-Newman-Keuls tests were used to evaluate the data. The results revealed that Chelon-Fil released significantly (P < 0.001) more fluoride for the first 7 days than all the other products. This was followed by Fuji II LC, which exhibited significantly more fluoride release than the rest of the materials for the same 7 days. At days 14 and 28, Chelon-Fil, Dyract, and Fuji II LC released similar amounts of fluoride that were significantly greater than the other products. Group 6 (Vitremer + Scotchbond Multi-Purpose) released significantly less fluoride than the other materials at all time intervals. Fluoride release for all products at days 1 and 2 was significantly greater than the rest of the time intervals, except for Chelon-Silver, which released similar amounts of fluoride for days 2, 3, 4, and 5. Although significance for the remaining time intervals varied for all materials, all fluoride release decreased from day 1 to day 28.

The purpose of this in vitro study was to compare the marginal ridge fracture resistance and microleakage following restorations of partial tunnel preparations using glass ionomer and glass cermet cements. Sixty eight sound premolars were selected for this study and were divided randomly into six groups. A standardized partial tunnel preparation was done on all the teeth except specimens belonging to Group I. The partial tunnel preparations of Groups III & V were restored with glass ionomer and that of Groups IV & VI were restored with glass cermet. The teeth belonging to Groups I, II, III & IV were subjected to marginal ridge fracture resistance testing. The teeth of Groups V & VI were tested for microleakage after immersing them in 5% methylene blue solution for 4 hours. The results indicated that the teeth restored with glass cermet were marginally better than that with glass ionomer in terms of marginal ridge fracture resistance. Both the materials failed to reinforce the marginal ridge to the level of an intact tooth. The microleakage which occurred around both the materials were statistically insignificant, but on comparison glass ionomer showed better results. Hence, glass ionomer is preferred as a restorative material for partial tunnel preparations because of additional inherent advantages like superior esthetics and fluoride leachability.

Various studies have shown that glass ionomers are susceptible to brittle fracture and acid conditions and that they undergo long-term changes in their mechanical properties. Little information is available on how brittleness, acid susceptibility, and long-term changes are reflected in the wear characteristics of glass ionomers. The purpose of this study was to evaluate long-term changes in conventional glass ionomers, metal-reinforced glass ionomers (including a cermet), and (light-curing) resinmodified glass ionomers by wear experiments simulating the wear process in occlusal contact-free areas. The wear tests were conducted periodically over a period of one year. In addition, wear was determined after one year at a pH of 5 or 6, for assessment of acid susceptibility, and at a condition as found in the occlusal contact areas. All materials showed high early-wear rates which decreased significantly during the one-year test period. This long-term process may be related to a slow progression of the acid-base reaction extending over several months. At each stage, the resinmodified glass ionomers wore significantly faster than the acid-base setting glass ionomers. Most of these materials were not affected at a pH of 6.0, while at a pH of 5.0 only the conventional and the metal-reinforced glass ionomers showed increased wear. Direct contacts with the antagonist led to a significant increase in wear in comparison with contact-free wear, probably as a result of sub-surface fatigue phenomena. In view of the unfavorable wear characteristics of the resin-modified glass ionomers and the high early wear of the conventional glass ionomers, including the metal-reinforced glass ionomers, it was concluded that none of these materials can yet be recommended for use in high-stress-bearing situations.

The development of adhesive restorative materials has led to more conservative cavity design with greater reliance being placed upon the bond of a material with tooth tissue for retention of the restoration. Glass-ionomer cements may offer particular advantages but have yet to achieve the durability reported for amalgam. This study reports on the results of a 2.5-year prospective clinical trial comparing the durability of two glass-ionomer cements, a conventional material (Ketac Fil) and a metal reinforced cermet (Ketac Silver) in the restoration of Class II lesions in primary molars. Forty-six pairs of restorations were assessed in 37 children. The failure rate of Ketac Fil, 23%, was significantly lower than that of Ketac Silver, 41% (P < 0.05). The median survival time of the Ketac Fil restorations was significantly greater, 25.3 months, than that of the Ketac Silver restorations, 20.3 months (P < 0.05). These values may be an underestimate of the true longevity of both restoration types as many of the restorations survived intact at the censor date. Neither the age of the child nor the tooth restored influenced the durability of the restoration. The deterioration in both marginal integrity and anatomic form of the Ketac Silver restorations was significantly greater than the Ketac Fil restorations (P < 0.05). The durability of Ketac Silver was such that it cannot be recommended for use in restoring carious primary molars.

Inadequate adaptation of a filling material to a gold crown can promote the passage of bacteria; thus, recontamination of sound dentin and/or the pulp canal space is feasible. The aim of this study was to determine the marginal microleakage between two different amalgams (Tytin and Valiant PHD-XT), three different composites (Tetric, Charisma, and Polofil Molar), and one glass-ionomer cement (Ketac Silver) and gold cast crowns using a helium gas microleakage method. In order to standardize the research parameters, gold washers with standardized dimensions were used as study models together with a helium leakage testing device. Standardized cavities were filled according to the manufacturers' recommendations with the different materials. The amount of helium passing the marginal interface between the fillings and cavities was measured with a mass spectrometer 48 hours after the fillings were placed and 100, 1000, and 2000 thermocycles (5 degrees C-55 degrees C). The results showed that amalgam allowed the least microleakage. Ketac Silver showed the greatest microleakage. Statistically significant differences were found between the composites and both amalgams and Ketac Silver between the 48-hour and 100-thermocycling groups. Yet, Ketac Silver showed a significant ascending tendency when compared to the composites and amalgams after 100, 1000, and 2000 thermocycles.

The aim of this study was to investigate the microleakage around Class II glass ionomer restorations in primary molars. Two different glass ionomer cements and one amalgam control were assessed in vitro by acidified gel technique. Assessment of caries-like lesions was performed using polarized light microscopy. The traditional glass ionomer (Chemfil II) with dentin conditioner provided the highest protection against caries attack and the amalgam restorations provided the least.

A new generation of filling materials, the hybrid-ionomer cements, has been introduced recently. In many clinical situations these hybrid ionomers may be an alternative to conventional glass-ionomer cements and resins bonded with dentin bonding agents. During the past years research has focused on factors influencing bond strength of dentin bonding systems, but there is not much knowledge about the bond strength of hybrid- and glass-ionomer filling materials under different conditions. Bond strengths of four hybrid ionomers, one conventional glass-ionomer cement, and one cermet cement were determined in superficial and deep, dry and moist dentin using a simplified pulp chamber model. All materials showed significantly higher bond strength to superficial compared to deep dentin. Moisture showed no significant influence on any material neither in deep nor in superficial dentin. Bond strengths of Fuji II LC, Variglass, and Vitremer were distinctly higher than those of the conventional glass-ionomer cement (Ketac-Fil) and the cermet cement (Ketac-Silver), while that of Photac-Fil was not significantly different. Ionomer samples failed cohesively in superficial dentin in over 60% of the samples. The bonding interfaces between Fuji II LC and Variglass and the treated dentin surface showed tags but no distinct hybrid layer. Bond strength is not only dependent on the pretreatment of the dentin, but also on the glass-ionomer resin composition of the material.

The treatment of fractured teeth poses significant problems for the practitioner. However, once the treatment planning decision has been made to attempt to retain the tooth, various practical regimens are available to effect this goal. This paper addresses the specific use of glass ionomer in the restorative management of incompletely, vertically fractured molar teeth integrated with specific root canal treatment techniques.

Fifty-four pairs of restorations (one glass ionomer and the other amalgam) were placed in the mouths of 36 xerostomic head and neck cancer patients. Patients were either fluoride users or fluoride nonusers. In patients who used a daily application of a mildly acidic (pH 5.8) sodium fluoride gel, glass-ionomer cements failed and amalgam restorations did not (P < 0.0001). In patients who neglected to use their topical fluoride as directed, glass-ionomer cement restorations did not fail, but amalgam restorations did (P < 0.001). The mean time to restoration loss for both restorative materials was 8.5 months. In severely xerostomic patients these findings were exaggerated.

Proper restoration of endodontically treated teeth is a frequent challenge to many clinicians. The majority of restorations are using various types of vertical support that can be placed in teeth, these include different prefabricated post systems as well as cast posts and cores. Less emphasis, unfortunately, has been placed on the materials utilized for final build up. Unless the tooth being treated undergoes minimal loss of tooth structure some from of augmentation will be necessary to increase the tooth strength and provide adequate support and retention for the final cast restoration. It is generally accepted that the ideal methods of corono-radicular buildup for nonvital teeth is a properly fabricated cast post and core.

Three formulations of glass ionomer filling materials were finished with discs lubricated with either water or petroleum jelly. No changes in surface micromorphology or marginal adaptation were found which would indicate that petroleum jelly should be used as a lubricant during finishing instead of water.

Most commercial dental composites contain liquid dimethacrylate monomers (including BIS-GMA or variations of it) and silica-containing compositions as inorganic reinforcing filler particles coated with methacrylate-functional silane coupling agents to bond the resin to the filler. They also contain initiators, accelerators, photo-initiators, photosensitizers, polymerization inhibitors, and UV absorbers. Durability is a major problem with posterior composites. The typical life-span of posterior composites is from three to 10 years, with large fillings usually fewer than five years. Polymerization shrinkage and inadequate adhesion to cavity walls are remaining problems. Some pulp irritation can occur if deep restorations are not placed over a protective film. Some have advocated the use of glass-ionomer cement as a lining under resin composite restorations in dentin. The concept of glass-ionomer cements (GICs) was introduced to the dental profession in the early 1970's. Current GICs may contain poly(acrylic acid) or a copolymer. Higher-molecular-weight copolymers may also be used to improve the physical properties of some GICs. Stronger and less-brittle hybrid materials have been produced by the addition of water-soluble compatible polymers to form light-curing GIC formulations. The ion-leachable aluminosilicate glass powder, in an aqueous solution of a polymer or copolymer of acrylic acid, is attacked by the hydrated protons of the acid, causing the release of aluminum and calcium ions. Salt bridges are formed, and a gel matrix surrounds the unreacted glass particles. The matrix is adhesive to mineralized tissues. Provisions must be made for maintenance of the water balance of restorations for the first 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Metal reinforced glass-ionomer cements are said to possess superior mechanical properties when compared to non-metal reinforced glass-ionomer cements. However, the literature to date does not always support this view, owing to the variety of materials and test methods employed. In this study the mechanical properties of three reinforced and three standard materials were tested using the standard specification tests of compressive and diametral strength in addition to tensile strength using the four point bend test. The tensile strength was also measured using the shell test in order that this test, which on theoretical grounds is more suited to these materials, may be evaluated. Six specimens of each material were prepared for each of the test modalities resulting in the conclusion that the addition of metal to glass-ionomer cements can markedly increase the strength of the materials. However, the method of fusing the metal to the glass rather than by simple addition does not produce any advantages in strength. In this evaluation one reinforced material was significantly stronger than all other materials in all four test modalities. The compressive strength test which appears in most standards does not appear to be very discriminatory. Of the tensile tests, which have more clinical significance, the results of the diametral strength tests, which are included in some standards, appear to be at variance with the other two tensile tests, suggesting that the flexural or shell test would be more appropriate.

The aims of this study were to assess microleakage at the cervical margins of class 2 "sandwich" restorations placed with two glass-ionomer-silver cements in primary molars, to compare the quality of the occlusal margins of these restorations to those prepared with Miracle Mix and Ketac Silver, and to assess by scanning electron microscopy (SEM) the marginal micromorphology of those restorations. Fifty-two class 2 restorations were prepared in extracted primary molars and were restored as follows: 1) Ketac Silver + Estilux Posterior (sandwich), 2) Miracle Mix + Estilux Posterior (sandwich), 3) Ketac Silver only, and 4) Miracle Mix only. No or minimal leakage was evident in most of the occlusal margins, whereas severe leakage was observed in almost 70% of the cervical margins of the Ketac Silver groups. Scanning electron microscopy evaluation demonstrated good adaptation at the buccal and lingual margins of all the restorations. Sixty-seven percent of the Miracle Mix restorations had no defects at the cervical margins, as opposed to only 17% of those with Ketac Silver.

The use of glass-ionomer cements in clinical dentistry is now well established. They have a number of unique properties, including adhesion to moist tooth structure, biological compatibility, and anticariogenic properties due to their fluoride release. Their use in treating early carious or erosion lesions has been widely investigated. Established techniques include fissure filling and sealing, restoration of class 5 erosion lesions without cavity preparation, and the internal occlusal fossa or tunnel restoration. The "sandwich" technique using glass-ionomer cements as "dentin substitutes" has enabled composite restorations to be used with greater safety where pulpal damage may occur. The future probably lies in using a laminate technique where materials that attach to dentin and form a biological seal can be covered by tougher and harder enamel veneers, thus mimicking the structure of the tooth. The deficiencies of glass-ionomer cements are well known, including lack of toughness, early water sensitivity, low abrasion resistance, and porosity leading to poor surface polish. Solving these problems is formidable, since inherently the strength of these cements is related to their water content. The clinician should be aware of these deficiencies and stay within the parameters of the techniques outlined in this paper. In particular, clinical success depends upon early protection of the cement from hydration or dehydration, and the current use of light-cured bonding agents has largely solved this problem.

The present study compares the compressive strength after one week of some conventional glass-ionomer restorative materials with that of glass ionomers reinforced by the addition of ceramic-coated silver or dental amalgam alloy particles to the aluminosilicate glass powder. Apart from the commercially available Ketac Silver and Miracle Mix, experimental mixtures of Fuji II glass-ionomer powder, the old as well as the new version, with various amounts of either a spherical or lathe-cut amalgam alloy were investigated. For the conventional glass ionomers, the mean compressive strength based on all measurements amounts to 159.9 +/- 4.5 MPa. Both formulations of Fuji II have a comparable strength after one-week maturation. The compressive strength of Ketac Silver does not differ significantly from that of Ketac Fill or from that of the conventional glass ionomers investigated. The effect of admixing amalgam alloy on the compressive strength is found to be determined by the shape and the amount of the alloy particles. Moreover, both parameters are interactive with the formulation of the Fuji glass ionomer used for preparation of the mixture. The results indicate that when dental amalgam alloy is added to the glass ionomer, lathe-cut particles are to be preferred but only in an amount up to 20% by weight.

Comparison was made of the apical microleakage of retrograde fillings with amalgam and with silver glass ionomer cements using a modified dye penetration method. Forty instrumented human teeth were divided into four groups. Each group was characterized by a different retrograde filling material or technique: Group 1--silver glass ionomer (SGI); group 2--SGI with previous acid wash of the cavity; group 3--SGI in a previously acid washed cavity, protected with varnish; and group 4--zinc-free amalgam. A paper cone for dye adsorption analysis was placed in contact with retrofill and the main canal was obturated with thermoplasticized gutta-percha. All teeth were coated, immersed in methylene blue dye, and evacuated to assure complete penetration of the dye in any possible void. Later the teeth were cleared and evaluated under stereomicroscope. Statistical analysis showed that group 1 had the least microleakage of all. In addition, the biocompatibility of the SGI and varnish was compared with that of amalgam using the 51Cr release evaluation method. The results showed that SGI and varnish were less cytotoxic than amalgam. It was concluded that SGI cement can be considered an alternative retrograde filling material.

This in vitro study examined the marginal integrity of Class II lesions using three restorative techniques. Class II preparations (MO and DO) were placed in 30 teeth. Half had the cervical margin placed 1 mm below the CEJ, the remaining had cervical margins 2 mm above the CEJ. The preparations were randomly restored using three techniques: 1) Glass ionomer liner and posterior composite resin; 2) Glass ionomer silver cermet placed in the proximal box to the contact area and the remainder restored with posterior composite resin; 3) Glass ionomer silver cermet only. All 30 teeth were loaded with 17 kg, thermocycled and stored in 37 degrees C solution for 30 days. The teeth were again loaded, immersed in 2% basic fuchsin solution for 24 hours, sectioned and photographed. Microleakage was calculated, according to the depth of dye penetration. Results demonstrated Techniques 1 and 2 to have less marginal leakage than Technique 3 when preparations remained in enamel and Techniques 1, 2 and 3 when preparations were below the CEJ. The chi-square test indicated a statistically significant difference between restoration technique and marginal microleakage (P less than 0.001).

The surfaces produced by different finishing techniques at two different time intervals following placement of three glass ionomer cements are compared by SEM-evaluation. All finishing procedures impaired the surface texture obtained under a matrix strip. Finishing of glass-ionomer cement restorations is best performed with flexible discs at 24 hours after placement. Initial finishing after 15 minutes using water spray is detrimental to the glass-ionomer cement surface. A useful procedure is to apply a lubricant during finishing of the cement.

Chelon Silver (C), Ketac-Silver Aplicap (K), Miracle Mix (M) silver-reinforced glass ionomers, and Valiant PH.D were evaluated as in vitro repair materials for cores. The core materials were placed in a 6 x 3 mm mold and stored at 37 degrees C at 100% RH for 24 hours. The cores were roughened with a coarse diamond. Five samples were conditioned (T) with Dentin Conditioner for 20 seconds, whereas another 5 samples were untreated (U). The cores were then repaired with C, K and M and subsequently tested after additional storage for 24 hours. Bond strength (MN/m2) was measured in tension using an inverted cone bond test at a crosshead speed of 0.05 cm/min. Mean bond strengths (S.D.) for the three repair materials when averaged over the three glass ionomer cores were: K, 5.0 (1.2); M, 3.4 (1.2) and C, 2.7 (1.5) for condition U; and M, 4.2 (1.1); K, 3.4 (1.2); and C, 3.1 (1.0) for condition T, where M, K and C were the repair materials. The Tukey intervals at the 95% level were 0.7 among materials and 0.5 between treatments. Bond strength of repaired amalgam was only successful with M, 0.9 MN/m2. Bond strengths to untreated silver-reinforced glass ionomer cores were higher with K used as a repair material.

The objective of this study was to determine the shear bond strength of dental amalgam bonded to dentin with adhesives. Four groups of 15 permanent posterior teeth were used in this study. The occlusal enamel of the teeth was removed to produce a flat dentin surface. The teeth were embedded in phenolic rings with acrylic resin. Vinyl polysiloxane ring molds 4 mm thick with 4.5 mm circular openings were attached to the exposed dentin surface. Adhesives applied to the dentin surfaces prior to amalgam placement and condensation included: Amalgambond, a 4-META/TBB-MMA, HEMA based system (A), Panavia EX, a modified phosphate ester of Bis-GMA luting system (P), and Ketac-Cem, a glass ionomer luting cement (K). A dentin bonding agent and composite resin restoration system (Scotchbond 2/Silux Plus) was included for comparison. The specimens were stored in 37 degrees C water for 7 days prior to testing. Shear bond tests were done in an Instron machine at a crosshead speed of 0.02 inches per minute. The data were analyzed by ANOVA at 5% level of significance. The differences in shear bond strengths of the four test groups were not statistically significant (P = 0.115). Fracture patterns of the bonded amalgams, examined by SEM, were adhesive in appearance for Groups A and K and cohesive for Group P.

Although the glass-ionomer cements were developed in the 1970s, it is only recently that their clinical use has expanded internationally. Improvements in formulation have resulted in better mechanical strengths, increased translucency and, more importantly, faster setting times. Their use as 'dentine substitutes' has expanded the versatility of laminate restorations in anterior and posterior teeth and the introduction of the silver-cermet ionomers provided materials with increased abrasion resistance. Glass-ionomer cements have a number of unique properties, including adhesion to moist tooth structure, biological compatibility, and anticariogenic properties due to their fluoride release. One of the major roles is the treatment of early carious lesions using microcavity preparation. However, like all materials, glass-ionomer cements have their weaknesses, the prime ones being lack of toughness, early water sensitivity, and porosity leading to poor surface polish. Future research should concentrate on correcting these deficiencies.

The effect of acid etching on the surface appearance and flexural strength of four glass polyalkenoate cements was investigated. Specimens were etched for intervals of 10-60 s, both at the recommended time after mixing and after a 24-h delay. The surface texture was examined microscopically. Further specimens were subjected to a 4-point bend test following etching 1 h and 24 h after mixing. Deterioration of the surface appearance occurred as the etching time was increased beyond 10 s following immediate etching. Etching after 24 h reduced surface damage, but a 10-s etch still gave the most favourable surface appearance without loss of particulate material. Etching beyond 10 s significantly reduces flexural strength.

The aim of this study was to compare the abrasion resistance and surface hardness of four glass-ionomer cements. The effects of hydration and dehydration on wear resistance were also studied. A composite material, enamel, and dentin were used as controls. For wear testing, the specimens were abraded on abrasion discs under water. All glass ionomers showed greater wear than composite and enamel, but less wear than dentin. Ketac-Fil showed the highest and Ketac-Silver the lowest wear resistance. Hydration or dehydration of the specimens did not significantly influence the wear rate of conventional glass ionomers, but the wear resistance of Ketac-Silver was increased due to dehydration. Ketac-Fil had the highest and Ketac-Silver the lowest hardness rating of the glass ionomers. The cement material did not show abrasion resistance better than that of the conventional glass ionomers, as has previously been suggested.

The creep of microspecimens of five glass-ionomer filling materials and one glass-ionomer-cermet cement was studied by means of a torsional creep apparatus. The glass-ionomer specimens were aged one week and conditioned in 37 degrees C water. Shear stress of 2.47 x 10(-4) N.m was maintained for three h, and recovery was followed for 50 h. Creep curves were obtained at 21, 37, and 50 degrees C. The effect of temperature increase was studied. All the glass ionomers exhibited linear visco-elastic behavior at low deformations. Their shear moduli and resistance to creep were similar to those of some composites measured by the same method. The increase of temperature influenced the creep behavior and moduli of the materials (i.e., increased creep and residual strains and decreased shear modulus). Although the applied torque was very small, there was permanent deformation, the result of viscous flow in all experiments which was more pronounced at 50 degrees C.

Four different methods for finishing and polishing the surfaces of two different glass-ionomer cements were studied by measuring the roughness of specimens at different stages of the procedures. Method 1 consisted of the four 3M Sof-Lex XT discs. Method 2 included a round, fine-grit diamond and the Vivadent polisher. In method 3 a round Arkansas stone and the Vivadent polisher were used. Method 4 comprised medium and fine sand and fine cuttle paper discs. Petroleum jelly was always used, to prevent heating and desiccation of the specimens. The cements used were KetacFil and KetacSilver. The smoothest surface was found after removal of the strip. The Sof-Lex medium disc gave the least rough surface for KetacFil, whereas the fine cuttle disc gave the smoothest finish for KetacSilver. Discs in sequence are to be preferred to diamonds and stones.

This laboratory study evaluated the dimensional stability of two reinforced glass ionomers (Ketac-Silver and Fuji Miracle Mix) in comparison with amalgam. Ten core build-ups were prepared with each material on extracted human teeth. Four Minim pins were placed in each tooth for retention. A gold casting was made for each core build-up. The specimens were placed in a distilled water and the distance between the casting and the tooth was measured at 1 hour, 6 hours, and then every 24 hours for 7 days. After 7 days, the measured changes were small, ranging from 1 to 63 microns. The reinforced glass ionomers were found to be dimensionally stable in moisture over a period of 7 days.

Conservative dentistry in developing countries often poses a problem because of lack of expensive dental equipment. This survey was undertaken to test two more appropriate filling materials in vivo. In 94 secondary school students (in Mzuzu, Malawi) with two or more cavities, one cavity was prepared in the conventional way using drilling equipment and then filled with amalgam, and one cavity was prepared using hand instruments only and filled with either cermet ionomer or "miracle mix". Models of the filled teeth (99 amalgam, 53 "miracle mix", 54 cermet ionomer; all of them Class 1) were made and evaluated by three examiners after 6 months and after 1 yr. The fillings were given a score on a four-point scale. One year later all types of filling materials had significantly decreased in quality, but only five fillings (one amalgam, one "miracle mix", and three cermet ionomer) needed replacement. Compared to the amalgam filling in the same mouth, more cermet ionomer and "miracle mix" fillings performed poorly, but these differences were not statistically significant after 1 yr. Both cermet ionomer and "miracle mix" are very promising alternatives for Class I tooth cavities in areas without dental equipment.

The purpose of the study was to evaluate four materials (a glass ionomer (polyalkenoate) silver cermet, two composite resin restoratives and a high copper content dental amalgam) placed in either conventional Class I cavities or in modified odontotomy-enameloplasty-sealant (OES) fissure preparations. One experienced operator inserted 438 occlusal. Class I restorations in the posterior permanent teeth of 124 patients in a private dental practice. Restorations were assessed for bulk loss of material, surface voids and cracking, restoration margin fractures and staining, and surface staining and roughness, by using colour transparencies taken at baseline and at recalls for up to 3 years. The glass ionomer cermet was the most difficult material to handle and also gave the least satisfactory clinical result. Loss of material and surface voids were common in the cermet restorations with surface cracking or crazing being seen in 11.4 per cent of the restorations, especially in the larger, conventional Class I preparations. One posterior resin was more viscous and difficult to handle than the other resin and exhibited more surface voids. The amalgam alloy was used in Class I preparations only and showed more restoration margin fractures and surface staining than did the other three materials. However, there were no unsatisfactory clinical assessments given for either restoration margin fracture and staining, or surface staining and roughness for any of the materials. Patient acceptance of the modified OES fissure preparation was extremely good.

Fluoride was extracted by 1 or 50 ml deionized water from 0.3 ml samples of two conventional and three metal-reinforced glass-ionomer cements. The fluoride concentration was determined by electrode. It was found that the fluoride concentration around the glass-ionomer cements ranged 2-3 ppm after 15 min and 3-5 ppm after 45 min. The maximum fluoride concentration attained within 24 h varied from 15-21 ppm, while the total amount of fluoride released during 100 days varied from about 2 mg fluoride to 12 mg fluoride per ml glass-ionomer cement. An alloy reinforced cement and its conventional counterpart released the highest amount of fluoride whereas a glass-cermet type released the lowest amount. Within the premises of this study it was concluded that composition and handling of the cements are of importance for the release of fluoride, and that a caries inhibitory fluoride concentration can be established in the surroundings of all of the cements.

A technique is presented for the expedient placement of interim buildups of type II glass ionomer cement as an aid for endodontic isolation of broken down teeth. The bond strength of glass ionomer cement to tooth structure is sufficient to withstand the forces of endodontic manipulation without the need for reinforcing pins. The material also shows promise as an intermediate endodontic seal. Variations of this technique are presented to address some other common isolation problems and the esthetic needs of the patient.

In the study, scanning electronmicroscopy and x-ray microanalysis techniques were used to examine a silver-reinforced glass ionomer cement. Scanning electron microscopy was used to evaluate surface topography and microstructure. Microcracking and a bimodal pore distribution were observed. The cement consisted of unreacted glass particles surrounded by a silica gel "halo" and embeded in an organic salt matrix. Back-scattered electron microscopy and energy-dispersive spectroscopy detected discrete clusters of silver atoms within the material. Other elements, such as calcium and aluminum, were dispersed homogeneously. Wave-length dispersive spectroscopy was used to detect fluoride, which also appeared to be homogeneously distributed. Electron microscopy and x-ray microanalysis techniques could prove valuable in clarifying the microstructure and fluoride release mechanisms of glass ionomer cements. Refinement of some aspects, including sample preparation, will be necessary to obtain consistently reliable results.