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PubMed1990

Tensile and shear strength of orthodontic bracket bonding with glass ionomer cement and acrylic resin. An in vitro comparison.

The tensile and shear strength for a polyalkeonate luting cement (AquaCEM) and a no-mix acrylic resin (Unite) in orthodontic bracket bonding were compared in an in vitro test. Brackets bonded/cemented to extracted premolar teeth were subjected to loads in a universal testing apparatus and the dislodging forces were recorded. The possible influences of setting time and of bracket base design were also studied. No significant differences between the cement and the resin were found after allowing 24 hours of setting time. This in contrast to the significantly stronger tensile strength but inferior shear strength for the polyalkeonate cement when stress was applied after 15 minutes. A significantly higher tensile strength value was recorded for a foil-meshed bracket base type compared to an integral base type with cut grooves after 15 minutes, but not after 24 hours. While the polyalkeonate cement adhesion mostly fractured within the cement layer, the acrylic bond more often failed in the enamel-adhesive interface. The results support the use of the fluoride-containing cement as an alternative to acrylic adhesives in orthodontic bracket bonding, especially in high-risk caries patients.

Acrylic Resins↗
PubMed1990

[Bonding of visible light cured composite resins to glass ionomer and Cermet cements].

The "sandwich" technique involves combination of composite resins to etched glassionomer cements, is used today in restorative dentistry. The purpose of this study is to evaluate the bond strength between several composite resins and glass ionomer or cerment cements. Cylindrical specimens of the cements Ketac-Silver, Ionobond and GC-Lining Ce-ment were inserted in a mold and their flat free surfaces were etched for 30". Cylindrical plastic tubes were set upon each one of these surfaces and filled with the Composite resins Durafill, Brilliant Lux, Estilux posterior, Estilux posterior CVS and Herculite XR. Half of the specimens transferred in tap water for 24 hours and the others after thermocycling in the first month, kept for 4 months. Shear bond strengths were determined in Monsanto Testing Machine and some fractured surfaces were examined under SEM. The results of this investigation indicate that this technique produces bond strengths between composite resins and glassioners and the combination type of resin and type of cement, affects the values of the strength. Glass cermeet--small particle resin provides the most effective strength and glass ionomer--microfill resins the least. Storage time and thermocycling don't significantly effect the bond strength. SEM examination showed that all fracture failures were obtained in the cement while the opposite resin surfaces were covered with particles of the cements.

Cermet Cements↗
PubMed1995

[Improvement in the primary stability of the dynamic hip screw osteosynthesis in unstable, pertrochanteric femoral fractures of osteoporotic bones by a new glass ionomer cement].

Internal fixation of unstable intertrochanteric fractures of osteoporotic femurs often leads to complications, which are primarily caused by the mechanically weak bone. The aim of this study was to test whether a new glass-ionomeric cement could reinforce the weak trabecular bone of the femoral head and thus improve the preliminary stability of dynamic hip screws (DHS) used for internal fixation. As a standardized model, a intertrochanteric osteotomy was performed on eight pairs of human, female, cadaver femora; a bony defect was also created medially to diminish support of the femoral neck. To stabilize the osteotomy a 135 degrees DHS was inserted. In one femur of each pair the glass-ionomer cement was applied to see whether this would enhance stability. The elastic and irreversible deformation of the internal fixation was measured at the osteotomy level under a cyclic load of 1400 N applied to the femoral head. In both the cemented and the uncemented cases, the femoral head shifted irreversibly in the caudal direction and tilted into a varus position. Movements of the femoral head in other directions were mainly reversible and small. The irreversible movement of the femoral head was significantly larger, approximately twice as great, following uncemented DHS fixation than after cemented fixation. Most movement occurred during the first ten load cycles; higher load cycles did not increase the irreversible deformation in the cemented group, but in the uncemented group a further increase in deformation was detected. These results indicate that internal fixation of unstable intertrochanteric femoral fractures can be significantly improved by the use of cement.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Access and the cementation of indirect restorations: a case report.

Through the pictorial presentation of a case study, this paper examines the role of rubber dam isolation in accommodating and maintaining the exacting access requirements of cementing indirect restorations. Technical tips to optimise the stability of the rubber dam for the duration of the procedure are introduced. Most educators will concede that cotton-roll-assisted isolation provides compromised but satisfactory access when dealing with non-resin cements. However, the relatively insoluble resin cements demand a more assiduous cementation procedure. The use of a customized matrix is offered as an example of the exacting demands of resin cementation, thus highlighting the distinction between the access requirements of traditional cementation as opposed to bonded restorations.

Cementation↗
PubMedDate not supplied

Effect of triturator speed variation on physical properties of encapsulated glass-ionomer luting cements.

This in vitro study evaluated the effect of variation of triturator mixing speed on the physical properties of two encapsulated glass-ionomer luting cements. Physical properties evaluated were working time, setting time, film thickness, and 24-hour and 7-day compressive strengths. Encapsulated glass-ionomer luting cements were mixed at 3000, 3500, 4000 (control), and 4500 cycles per minute (cpm). An oscillating rheometer was used to determine working and setting times. Film thickness and compressive strength were determined using methods described in ANSI/ADA Specification No 66 for dental glass-ionomer cements. Results of the study indicated that decreased mixing speed may prolong working and setting times for Ketac-Cem Maxicap and Fuji Cap I. Within the range of 3500 to 4500 cpm, variations in mixing speed do not significantly affect compressive strength or film thickness values for either cement. Excessively slow mixing speed (3000 cpm) often resulted in the presence of unmixed powder expressed from the capsule nozzle prior to the expression of mixed cement. The presence of this unmixed powder results in a decreased powder/liquid ratio, which may have an adverse effect on the physical properties of the set cement.

Analysis of Variance↗
PubMedDate not supplied

The effect of cement volume on crown seating.

This in vitro study examined the effect of cement volume on the seating of complete crowns. A spaced complete crown was made to fit a nickel-chromium replica mounted in a cementation jig that allowed static and dynamic seating. The crown was luted 10 times for each group using zinc phosphate cement under an initial static load followed by a dynamic load of 1,500 Hz. Seating was measured by a linear variable differential transducer. Mean vertical discrepancies for the three cement volumes were: completely filled (90.0 +/- 15.2 microns); half filled (42.1 +/- 8.6 microns); and brushed on (27.4 +/- 7.2 microns). Means differed significantly (P < .0005). This study indicated that a thinly brushed-on layer of luting cement gave smaller vertical seating discrepancies than greater volumes of luting cement.

Cementation↗
PubMed1997

A new resin-reinforced glass ionomer cement for use with orthodontic attachments.

Resin cements are commonly used to bond orthodontic appliances. However, etching enamel and bracket bonding is an extremely technique-sensitive process. Moisture and saliva control, particularly in the gingival third of posterior teeth, is difficult and time-consuming, but is critical to success. Recently, a light-cure resin-reinforced glass ionomer cement was shown to perform with equal bonding capacity. This is accomplished in a wet field, without etching, and with the glass ionomer feature of fluoride release. Now, a self-cure resin-reinforced glass ionomer cement has been introduced. The self-cure cement will provide equal clinical success in areas where light curing is not possible or desired. This article compares traditional resin cements and glass ionomer cements for bonding orthodontic appliances.

Acrylic Resins↗
PubMed1997

Bond strength and interface micromorphology of an improved resin-modified glass ionomer cement.

PURPOSE: To evaluate the influence of surface treatment with 20% polyacrylic acid containing 3% aluminum chloride (AlCl3) on the shear bond strength of an improved resin-modified glass ionomer cement to enamel and dentin, and to analyze the micromorphology of the cement-tooth interface. MATERIALS AND METHODS: Flat enamel and dentin surfaces of bovine incisors were ground up with sequentially finer abrasives to 1000-grit silicon carbide paper. Each surface was treated with 10% polyacrylic acid (Dentin Conditioner: DC) for 20 seconds or with 20% polyacrylic acid containing 3% aluminum chloride (Cavity Conditioner: CC) for 10 seconds, rinsed, and gently air-dried. A resin-modified glass ionomer cement (Fuji II LC) and its improved version (Fuji II LC-I) were applied to the tooth substrate, and bond strengths measured at periods of 5 minutes, 1 day, and 1 week after light curing. As a control, the resin-modified glass ionomer cements were applied to untreated surfaces and were tested at 1 day. To evaluate the interface micromorphology, specimens were prepared following the adhesive-sandwich technique, cut in equal halves, and observed under a scanning electron microscope (SEM). Additionally, in order to observe the effect of surface pre-treatment of each conditioner on dentin, pre-treated dentin disks were freeze-dried, fractured, and the morphology of the treated and fractured surfaces were observed. RESULTS: Shear bond strength of CC+ Fuji II LC-I to enamel was significantly higher than that of DC+ Fuji II LC at 1 day and 1 week (P < 0.0001). As for dentin, the improved system showed significantly higher bond strength at 5 minutes after light curing (P < 0.001), but bond strengths were not statistically different at 1 day and 1 week. Fracture patterns, examined with a stereomicroscope, were mixed adhesive/cohesive within the cement for all groups. Interface micromorphology, observed with an SEM, suggested the formation of a resin-rich layer and an indistinct zone between the resin-modified glass ionomer cements and the underlying dentin.

Acid Etching, Dental↗
PubMedDate not supplied

Effect of eugenol-containing temporary cements on bond strength of composite to enamel.

The purpose of this study was to find out the degree to which eugenol-containing temporary cements or temporary filling materials affected shear bond strength of a dual-cure resin luting cement to acid-etched enamel. For this purpose 56 human caries-free third molars were embedded in acrylic resin and cross sectioned mesiodistally. One of the corresponding halves was covered with Temp-Bond (eugenol-containing, Group 1), Provicol (eugenol-free, Group 2), ZOE (Group 3), and eugenol (Group 4). The other half of each sectioned tooth was kept clean and served as a control. After 1 week the cements were removed; the pure eugenol group (Group 4) was terminated after 24 hours. Plastic cylinders were filled with Dual Cement and placed on the etched enamel and light cured. Shear bond strength data were recorded using a Zwick Universal Testing Machine, and the mode of failure was diagnosed using a light microscope. Significant differences in shear bond strength could neither be found between the treated halves and the controls nor among the four groups pretreated with eugenol-containing or eugenol-free temporary cements. Based on the results of this study, no adverse effects of eugenol on shear bond strength of a resin luting cement to enamel could be found.

Acid Etching, Dental↗
PubMed1988

Long-term monitoring of microleakage of dental cements by radiochemical diffusion.

Radioactive 14C sucrose was found to be an ideal marker for microleakage because it did not penetrate tooth tissue, dental cement, or mounting resin. The main finding is that the adhesive cements--the glass-ionomer and polycarboxylate--are significantly more effective at preventing microleakage than are the traditional phosphate cements--silicate and zinc phosphate. The differences can be as high as two orders of magnitude. The adhesive cements provide almost perfect and reliable seals. By contrast, the nonadhesive cements are erratic sealants with most of the restorations leaking.

Carbon Radioisotopes↗
PubMed1978

A study of temperature changes occurring in setting dental cements.

A study has been made of the rise in temperature associated with the setting of dental cements. Results are discussed in terms of the chemistry of the cement systems and are related to specification testing and clinical usage. Zinc oxide cements evolve more heat than those based on ion-leachable glasses, and phosphate bonded cements evolve more heat than polycarboxylate cements.

Acrylic Resins↗
PubMed1989

A laboratory and clinical evaluation of three dental luting cements.

The loss of material from specimens of three luting cements was measured after continuous erosion cycling in the laboratory. The glass ionomer luting cement showed significantly less material loss than the zinc polycarboxylate and zinc phosphate luting cements. Two hundred and fifty restorations cemented with one of the three materials were studied clinically for marginal integrity and retention over 3.5 years. The data were tested using survival analysis. Zinc phosphate cement gave the best clinical performance. Possible explanations for the poor correlation between the findings in the laboratory and clinical study are discussed.

Dental Cements↗
PubMed2000

Marginal integrity after fatigue loading of ceramic inlay restorations luted with three different cements.

PURPOSE: To evaluate the effect of fatigue loading on the quality of the cement around the margins of adhesive ceramic MOD inlays. MATERIALS AND METHODS: Non-metal IPS Corum porcelain inlays were made and cemented either with the resin-based composite Variolink, the compomer Dyract-Cem or the glass-ionomer cement Ketac-Cem. For each system, half of the specimens were subjected to thermal and mechanical load cycling to simulate fatigue loading. All teeth were then sectioned and evaluated by SEM on topography and by optical microscopy for dye penetration. RESULTS: Before loading, all systems showed good marginal integrity. After loading, inlays cemented with Variolink and Dyract-Cem showed no significant (P > 0.05) increase in marginal break down, however restorations cemented with Ketac-Cem, showed a significant (P < 0.05) deterioration at the margins.

Cementation↗
PubMed1978

Intracoronal pressure during crown cementation.

A model system was developed which recorded the intracoronal pressure during crown cementation at three locations simultaneously. Peak pressures and residual pressures were greatest with zinc phosphate cement. The zinc oxide-eugenol cement generated the smallest amount of peak and residual pressures. The polycarboxylate cement exhibited an intermediate pressure intensity. The uneven intracoronal pressure in the cement suggests a complex flow pattern capable of developing the separation of phases that earlier work reported. However, the small residual pressure indicates that these internal back pressures appear to play a limited role in preventing a complete seating of a crown.

Cementation↗
PubMed1990

Bond strengths of luting cements to potassium oxalate-treated dentin.

Potassium oxalate is gaining popularity as a dentin treatment to prevent the development of dentin sensitivity. Because treated dentin surfaces are covered with calcium oxalate crystals, the bond strength of cements to oxalate-treated dentin required investigation. This study determined the tensile bond strengths of glass-ionomer, polycarboxylate, and zinc phosphate cements used to cement castings to dentin treated with either water or potassium oxalate. The results indicate that oxalate-treated dentin did not affect the bond strength of glass-ionomer or polycarboxylate cements, but produced a large decrease in the bond strength of zinc phosphate cement.

Dental Bonding↗
PubMed1995

Seating accuracy and fracture strength of vented and nonvented ceramic crowns luted with three cements.

Methods to facilitate the seating of artificial crowns can improve the gingival margins and ensure longevity. This study examined the effects of venting and different luting agents on the seating accuracy and compressive strength of Dicor ceramic crowns. Vented and unaltered anterior restorations were tested using zinc phosphate cement (ZnPO4), glass ionomer, and composite resin cement. Rexillium metal dies of a tooth preparation of a maxillary canine were provided and standardized crowns were fabricated. The artificial crowns were evaluated for adaptation of the finish line before and after cementation, then were compressively loaded to failure. Under the conditions of this study, neither the design of the artificial crown nor the luting agent had a significant effect on the compressive strength. Composite resinous cement appeared to enhance seating of the crown, whereas ZnPO4 cement inhibited seating.

Cementation↗
PubMed2000

Corrosion susceptibility of titanium covered by dental cements.

OBJECTIVES: The aim of this study is to determine the influence of acidic fluorinated cements (as glass ionomer (GI) cements) on the passivation of titanium, using electrochemical investigations. METHODS: We realized experimental electrodes that associate titanium and dental cements. Polarization resistance of titanium electrodes has been determined for uncovered metal and electrodes covered with three dental cements. Student's t-tests proved the reproducibility. We also compared successive voltammograms for uncovered titanium and GI covered titanium. RESULTS: Correct passivation was observed with zinc eugenate, but fluorinated GI or zinc phosphate coverage increased the corrosion susceptibility. SIGNIFICANCE: However there is no evidence of titanium depassivation when covered with cement. No clinical contraindication can be held.

Coated Materials, Biocompatible↗
PubMedDate not supplied

An in vitro evaluation of the integrity of stainless steel crown margins cemented with different luting agents.

The elderly population is retaining more teeth which require extensive restorations. The purpose of this study was to identify a luting agent which had the least marginal breakdown when used with stainless steel crowns. Thirty-six caries-free molars were selected, prepared for stainless steel crowns, and embedded in acrylic to support the crown and tooth. The crowns (Unitek/3M) were cemented with 4 different luting agents: (A) Fleck's Cement, (B) Ketac-Cem, (C) All-Bond C & B Cement, and (D) Panavia EX Cement. All the restored teeth were thermocycled and divided into 3 experimental groups. Twelve teeth were stained. The remaining teeth were occlusally loaded and stained. The remaining 12 teeth were thermocycled and stained again. The stainless steel crowns were then sectioned and photographed at 7.5x mag. The dye penetration was evaluated by measurement of the percentage of dye penetration from the crown margin to the cusp tip on each side. Statistical analysis found that the least dye penetration was with All-Bond C & B Cement (p = 0.0001). The most extensive penetration was observed in Ketac-Cem Occlusal loading was a significant factor (p = 0.0001) increasing the dye penetration, but the crown-tooth gap was not.

Aged↗