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PubMed1999

Volumetric microleakage assessment of glass-ionomer-resin composite hybrid materials.

OBJECTIVE: This study was intended to quantify the marginal leakage of three glass-ionomer-resin composite hybrid materials and compare it with the leakage exhibited by a glass-ionomer cement and a bonded resin composite system. METHOD AND MATERIALS: Standardized Class V cavities were prepared on root surfaces of 105 extracted human teeth, randomly assigned to five groups of 21 each, and restored with either Ketac-Fil Aplicap, Z100/Scotchbond Multi-Purpose Plus, Vitremer, Photac-Fil Aplicap, or Dyract. The teeth were thermally stressed for 500 cycles and stained with methylene blue. The microleakage was quantified spectrophotometrically, and the data were statistically analyzed with Friedman's test. RESULTS: There were no significant differences in microleakage among the five groups. Restorations of all tested materials showed some marginal leakage in Class V cavities. CONCLUSION: The microleakage performance of glass-ionomer-resin composite hybrid materials was similar to those of a conventional glass-ionomer and a bonded resin composite system.

Chi-Square Distribution↗
PubMedDate not supplied

In vitro comparison of the shear bond strength of amalgam to tooth structure using two bonding agents--lutting glass ionomer and 4-META.

Bonding dental amalgam to tooth structure using 4-META has become an accepted clinical procedure. Glass ionomer cements possess the ability to bind to tooth structure as well as to the components of dental amalgam. The present in vitro study evaluates the shear bond strength of amalgam to tooth structure using luting glass ionomer as a bond mediating agent, and compares with that obtained using 4-META. Results indicate that it is possible to bond amalgam to tooth structure using a thin layer of glass ionomer cement. The shear bond strength of glass ionomer cement mediated bond is significant and may be adequate for clinical application.

Bicuspid↗
PubMed1999

The glass spherical hollow orbital implant: a prospective study.

OBJECTIVE: Various types of orbital implants are in use in the rehabilitation of anophthalmic patients. The latest is the expensive hydroxyapatite implant. The study objective was to evaluate the effectiveness of low cost glass spherical hollow implants, as primary and secondary implants. SETTING: St Michaels and Frazer Private Hospitals, Colombo. STUDY DESIGN AND METHOD: 65 patients had glass sphere orbital implants between 1987 and 1995; 51 primary (evisceration 46, enucleation 5) and 14 secondary (evisceration 2, enucleation 12). At 9 to 12 months follow up, patients were evaluated for mobility of implant, prosthesis mobility, lid sulcus deformity, cosmetic results and complications. RESULTS: Primary glass spherical hollow implants provide excellent mobility of the implant (92%), cosmesis (88%), prosthesis mobility (67%), with a low rate of complications (9.5%). Results of primary implant was superior to that of secondary (p < 0.001). CONCLUSION: Excellent results were obtained with spherical glass spheres as primary implants following evisceration.

Adolescent↗
PubMed1998

Shear bond strength of resin-modified restorative glass-ionomer cements to dentin--an in vitro study.

An in vitro study was carried out on 40 periodontally involved, caries free human maxillary and mandibular molars to evaluate shear bond strength of resin- modified restorative glass-ionomer cements to dentin. Teeth were divided into four groups, Group I--Fuji II (Conventional glass ionomer) Group II (Fuji II LC), Group III (Vitremer), Group IV (Geristore). Shear bond strength was tested using a transaxial testing machine. Results showed that shear bond strength of all resin-modified restorative glass-ionomer cements was higher than conventional glass ionomer (Fuji II) tested. No statistical difference was found between Fuji II LC and Geristore. However, bond strength of Vitremer was lower than Fuji II LC and Geristore but higher than Fuji II.

Chemical Phenomena↗
PubMedDate not supplied

The effect of placement and quantity of glass fibers on the fracture resistance of interim fixed partial dentures.

PURPOSE: Polymers used in interim fixed partial dentures (FPD) have recently been reinforced with fibers. The aim of this study was to determine the influence of the position of the fiber reinforcement on the fracture resistance of interim FPDs. In addition, the influence of quantity of fibers and the length of span of the FPD on the fracture resistance was investigated. MATERIALS AND METHODS: FPDs were fabricated from a resin mixture of polyethylmethacrylate powder and n-butylmethacrylate liquid. Five FPDs from each group were made, and the FPDs were stored in water for 30 days before testing. The FPDs in the control group were unreinforced, and in the other groups the FPDs were reinforced either with two or three unidirectional continuous glass-fiber reinforcements and one woven glass-fiber reinforcement. Different quantities of fibers were used and the fibers were placed in different locations in the FPD. The load was applied to the FPD by a steel ball placed in the cavity in the middle fossa of the pontic tooth. RESULTS: The load required to fracture the unreinforced FPDs varied from 372 to 1061 N. Mean fracture load of reinforced FPDs varied from 508 to 1297 N. One-way analysis of variance showed that the length of span and the quantity of fibers significantly affected the fracture load (P < 0.001, n = 5). By lengthening the span of the FPD, the reinforcing effect of glass fibers became more obvious. CONCLUSION: The results of this study suggest that the effectiveness of glass-fiber reinforcement is most evident in interim FPDs with long spans and that the positioning of reinforcement considerably influences the strength of the FPD.

Analysis of Variance↗
PubMedDate not supplied

Fluoride release from three glass ionomers, a compomer, and a composite resin in water, artificial saliva, and lactic acid.

The amounts and the pattern of fluoride release from one metal-reinforced glass ionomer cement, two resin-modified glass ionomer cements, one compomer, and one composite resin placed in double-distilled water, artificial saliva, and lactic acid were evaluated in this study. Measurements of fluoride ion release were made for a total of 105 cylindrical specimens (10 mm in diameter and 1.5 mm in height). They were taken over a period of 16 weeks at the intervals of 4, 8, 12, and 24 hours, as well as 2, 3, 7, 14, 28, 56, and 112 days. The pattern of fluoride release was similar for all of the examined materials. The greatest amount of fluoride was released from the metal-reinforced glass ionomer Argion. The resin-modified glass ionomers Vitremer, Fuji II LC; the compomer Dyract; and the composite resin Tetric followed in ranking order. The pH of the environment strongly affected the fluoride release from the materials. There was a significant difference (P < 0.001) in the amounts of fluoride released in lactic acid vs water and artificial saliva, whereas, there was no significant difference (P > 0.05) in the amounts of fluoride released in water vs artificial saliva.

Analysis of Variance↗
PubMed2000

A 3-year follow-up study of preformed beta-quartz glass-ceramic insert restorations.

OBJECTIVE: The purpose of this study was to evaluate the clinical performance of preformed beta-quartz glass-ceramic insert restorations. METHODS AND MATERIALS: Nine Class I and 30 Class II beta-quartz glass-ceramic insert restorations were placed in 16 patients who were seen regularly by personnel at Umeå University Dental School. The California Dental Association criteria were used to evaluate the restorations at baseline, 6 months, and 1, 2, and 3 years after luting. The occurrence of postoperative sensitivity, the time taken to manufacture each restoration, and certain periodontal conditions were also evaluated. RESULTS: Sixty-nine percent of the restorations were rated satisfactory at the 3-year examination. During the follow-up period, 4 became loose and 7 were fractured or had flaking surfaces. Caries was registered in connection with 1 restoration. Excellent ratings were obtained for marginal integrity, anatomic form, surface, and color in 62%, 84%, 32%, and 44% of the restorations, respectively. There was no statistically significant difference in the occurrence of plaque and bleeding on probing in comparison with the controls. The mean overall time for placement was 38 minutes. The estimated survival rate (Kaplan-Meier) was 59% after 3.5 years. CONCLUSION: The quality of the beta-quartz glass-ceramic restorations in the present study was inferior to that presented in most earlier studies of ceramic or resin composite posterior restorations placed in patients treated at university clinics. Both the technique and the beta-quartz glass-ceramic inserts have to be evaluated in more long-term studies to assess the possibility of their serving as an alternative restorative technique.

Adult↗
PubMed2001

Radiopacity of glass-ionomer/composite resin hybrid materials.

This study visually compared the radiopacity of seven restorative materials (3 resin-modified glass-ionomer cements, 3 polyacid-modified composite resins, and 1 conventional glass-ionomer cement) to a sound tooth structure sample, and an aluminium stepwedge. All hybrid materials were more radiopaque, except for one resin-modified glass-ionomer cement, than both the tooth structure and conventional glass-ionomer cement.

Acrylic Resins↗
PubMedDate not supplied

Clinical survey of acrylic resin removable denture repairs with glass-fiber reinforcement.

PURPOSE: The aim of this study was to evaluate clinical usefulness and durability of continuous glass-fiber reinforcement in repair of acrylic resin removable dentures. MATERIALS AND METHODS: Fractured removable dentures without reinforcement, with conventional metal-wire reinforcement, or with mesh reinforcement were collected from two dental schools in Finland. The total number of dentures was 51 and the number of patients was 48. During the repair, the dentures were reinforced with a polymer-preimpregnated E-glass fiber at the region of the fracture. The fibers were used as partial fiber reinforcement, i.e., only the weakest part of the denture was reinforced. Follow-up time varied from 4 months to 4.1 years. After the follow-up period, possible fractures and discoloring were visually inspected. Possible irritation of oral mucosa by glass fibers and the general shape of the denture were also evaluated. RESULTS: In 88% of the cases, there was no need for adjustment at the region of partial fiber reinforcement, and the clinical condition of the dentures was good. Glass fibers did not irritate the oral mucosa. In the case of refracture or hairline fracture, positioning of the partial fiber reinforcement was incorrect or the reinforcement had been used incorrectly (the wetting of the reinforcement with denture base resin was inadequate). CONCLUSION: Polymer-preimpregnated partial fiber reinforcement seems to be useful in eliminating fractures of acrylic resin removable dentures. However, this study emphasizes the importance of correct positioning and accurate laboratory technique when partial fiber reinforcement is used.

Acrylic Resins↗
PubMedDate not supplied

Flexural strength of a glass-infiltrated alumina dental ceramic incorporated with silicon carbide whiskers.

PURPOSE: The addition of silicon carbide whiskers has been known to reinforce ceramics. This study compared the flexural strength of a glass-infiltrated alumina dental ceramic with various amounts of silicon carbide whiskers incorporated into the alumina matrix. MATERIALS AND METHODS: Three groups with a total of 30 specimens were included: glass-infiltrated alumina dental ceramic with 0, 0.125, and 0.25 wt% silicon carbide whiskers. The flexural strength was measured using a three-point bending test, and the data were analyzed with one-way analysis of variance. Scanning electron microscopy was used to examine the fracture surfaces of all three materials. RESULTS: There were no significant differences in the flexural strength among the three groups. Glass-infiltrated alumina dental ceramic failed predominantly by transgranular fracture and to a lesser degree by intergranular fracture. CONCLUSION: The addition of silicon carbide whiskers did not change the flexural strength of glass-infiltrated alumina dental ceramic.

Aluminum Oxide↗
PubMed2000

[Shear bond strength of glass ionomer cement for orthodontic bracket bonding].

OBJECTIVE: The purpose of this study was to investigate the shear bond strength of resin-modified glass ionomer used for orthodontic bracket bonding. METHODS: 30 extracted premolars were evenly divided into two groups. Edgewise brackets (Orsu) were bonded with resin-modified glass ionomer (Advance) in group one and with composite resin (DM) in group two. The shear bond strengths of two materials were tested by material testing machine after 24 hours. The adhesive remnant index was scored after debonding. RESULTS: The shear bong strengths of resin-modified glass ionomer and composite resin were (6.862 +/- 2.142) MPa and (7.183 +/- 3.205) MPa respectively. There were no statistically significant differences between two groups. CONCLUSIONS: In vitro bond strength of resin-modified glass ionomer had reached the same level of composite resin. It had the prospect of clinic use.

Composite Resins↗
PubMed2001

Identification of pharmaceutical glasses by laser ablation ICP-MS.

The chemical composition of pharmaceutical glasses (ampoules, infusion bottles, plunger) has been determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). A Nd:YAG laser with 10 Hz repetition rate in the Q-switch mode at its fundamental wavelength (1064 nm) was used to identify common types of pharmaceutical glasses. The following isotopes were used for measurements: 7Li, 11B, 23Na, 24Mg, 27Al, 28Si, 29Si, 30Si, 39K, 42Ca, 47Ti, 57Fe, 90Zr, 121Sb, 137Ba. Each analysis included the measurement of 12 craters. Relative standard deviations between 1.8% and 8.0% of the quantitative results were obtained. 29Si was used as internal standard. Standard reference materials (soda-lime-, lead- and borosilicate glasses) were used for external calibration of laser sampling. Linear calibration functions for each isotope were found. All samples and standard materials were digested in a two-step-procedure by nitric/fluoric acid, then measured and externally calibrated by ICP-MS with multi-elemental standard solutions using 45Sc as internal standard. Digestion and laser ablation results agree within 8% (confidential interval 95%) with the certified values. Intensity ratios of most isotopes also agree sufficiently with the corresponding theoretical values (+/- 18%). The developed method allows to distinguish different types of pharmaceutical glasses.

Calibration↗
PubMed2000

[An assessment of fluoride release from a compomer and four resin-modified glass-ionomers].

OBJECTIVE: To compare the fluoride release into water from a compomer (Dyract) and four resin-modified glass-ionomer cements (Fuji II LC, Photac-Fil, VariGlass, Vitremer). METHODS: Five specimens of each material were prepared according to manufacturers' instructions and placed into 3.0 mm diameter x 2.7 mm thick disposable Teflon molds. The specimens were placed in well-sealed polypropylene vials with 2 ml of de-ionized water and stored in an incubator at 37 degrees C. The solutions were replaced weekly and the levels of fluoride (ppm) were analysed at day 1, 7, 30 and subsequently every 28 days for 253 days. The results were analysed using one-way ANOVA followed by the Student-Newman-Keuls range test. RESULTS: All materials except the compomer (Dyract) showed high initial release values of fluoride which decreased exponentially, then showed a slow decline during the ensuing time. Initial fluoride release values were significantly different between Dyract, VariGlass, and the three other resin-modified glass-ionomers. The compomer released significantly less fluoride than did the other resin-modified glass-ionomers. CONCLUSION: With high caries risk patients, it may be most beneficial to use a high fluoride release resin-modified glass-ionomer cement as the restorative material of choice.

Acrylic Resins↗
PubMed2002

Comparison of atraumatic restorative treatment and conventional cavity preparations for glass-ionomer restorations in primary molars: one-year results.

OBJECTIVE: The purpose of this study was to compare the success rates of glass-ionomer cement restorations placed with the atraumatic restorative treatment approach and conventional cavity preparation methods. METHOD AND MATERIALS: Two encapsulated, high-strength, esthetic conventional glass-ionomer cements were placed in 82 Class I and 53 Class II atraumatic restorative treatment and conventional cavity preparations, and an encapsulated amalgam alloy was placed in 32 Class I conventional preparations, in vital primary molars of 60 Chinese children aged 7 to 9 years. RESULTS: The atraumatic restorative treatment preparations, made with hand instruments only, took approximately 50% longer to complete than did the preparations completed with conventional rotary instrumentation. After 1 year, there were no amalgam failures. For the glass-ionomer cement restorations, when the atraumatic restorative treatment method was used, significantly better survival rates were found for Class I (92.9%) than for Class II (64.7%) cavity preparations. There was also a strong trend for relatively better survival rates for the conventional cavity preparation method (86.7%) than for the atraumatic restorative treatment (64.7%) method for Class II cavity preparations. However, both the atraumatic restorative treatment and conventional methods appeared equally effective for Class I preparations. CONCLUSION: In a clinic setting, the use of atraumatic restorative treatment hand instruments for cavity preparation is more time consuming, and the method may also provide less mechanical retention and/or bulk of glass-ionomer cement for some Class II preparations in primary molars than does the use of conventional rotary instruments.

Child↗
PubMed2002

Laboratory strength of glass ionomer cement, compomers, and resin composites.

PURPOSE: The study evaluates the compressive, flexural, and diametral tensile strengths of 8 core build-up materials from different material classes (highly viscous glass ionomer cement, autocured resin composite, and compomers). MATERIALS AND METHODS: All materials were manipulated according to the manufacturers' recommendations for use as core materials. At a temperature of 23.0 +/- 1.0 degrees C the properties of compressive, diametral tensile and flexural strength were determined using a universal testing machine at 15 minutes, 1 hour, and 24 hours after material preparation. Using one-way analysis of variance (ANOVA), multiple mean value comparisons were performed to determine significant differences (p< or =.05) between the core restoration materials. RESULTS: The values for compressive strength varied from 40.3 +/- 5.2 MPa (compomer) to 237.4 +/- 37.3 MPa (autocured resin composite) for the 3 measurement times. At 15 minutes, 1 hour, and 24 hours after first mixing, the ANOVA showed significant differences (p < or =.05) between the resin composite Core Paste and all of the other materials. Diametral tensile strengths ranged from 5.5 +/- 1.1 MPa for glass ionomer cement to 39.1 +/- 2.9 MPa for composite core material. Three-point flexural strength showed values ranging from 12.1 +/- 2.5 MPa for glass ionomer cement to 92.1 +/- 9.7 MPa for compomer between the 3 measurement times. CONCLUSIONS: Setting time influences the mechanical properties of the materials tested in this study. Autopolymerizing resin composite Core Paste demonstrated greater compressive and flexural strengths at the 3 measurement times than the other materials tested. Reinforced composites, in comparison to the autocured resin composites, yielded no improvement in tensile strength. Flexural and tensile strengths of the glass ionomer cement were lower than those of autocured resin composites and compomers.

Analysis of Variance↗
PubMedDate not supplied

Glass ionomer cements in pediatric dentistry: review of the literature.

Glass ionomer cement systems have become important dental restorative and luting materials for use in preschoolers, children and teenagers. These materials form chemical bonds to tooth structure, are biocompatible, release fluoride ions for uptake by enamel and dentin, and are able to take up fluoride ions from dentifrices, mouthwashes, and topically applied solutions. Unlike early glass ionomers, the new cement systems are easy and practical to use. Resin-modified glass ionomer cements not only have improved physical characteristics, but the photopolymerizable resin component reduces initial hardening time substantially. This article reviews the development and history of glass polyalkenoate cement systems and their ongoing role in dentistry for children.

Adolescent↗
PubMedDate not supplied

Intrascleral implantation of glass beads during evisceration.

BACKGROUND AND OBJECTIVE: To review the results after small glass bead implantation in the scleral cavity during evisceration. MATERIALS AND METHODS: In this retrospective study, we retrieved the follow-up data of 17 patients who underwent evisceration with glass bead implantation from 1993 to 1996. RESULTS: All patients achieved good cosmetic results with good motility of the prosthesis. Complications included transient chemosis at the early postoperative period in 3 patients (17.6%), 1 patient (5.9%) with local dehiscence of the wound, 1 patient developed a cyst in the socket (5.9%), and 1 patient was afflicted with thinning of the conjunctiva over the surgical wound. CONCLUSION: The use of glass beads to fill the scleral cavity during evisceration has the advantage of an excellent fit in accordance with the scleral cavity volume, as well as ease of treatment in case of extrusion. The prosthesis movement is good because of its engagement with the scleral bulges caused by the glass beads.

Adult↗
PubMed2002

[In vitro drug release behavior of carrier made of porous glass ceramics].

OBJECTIVE: To conduct the in vitro test on drug release of rifampin encapsulated in a carrier made of porous phosphate glass ceramics and to analyze main factors which affect the drug release rate. METHODS: A certain quantitative of rifampin was sealed in a hollow cylindrical capsule which consisted of chopped calcium phosphate crystal fiber obtained from glass crystallization. The rifampin concentration was measured in the simulated physiological solution in which the capsule soaked. RESULTS: Rifampin could be released in a constant rate from the porous glass ceramic carrier in a long time. The release rate was dependent on the size of crystal fiber and the wall thickness of the capsule. CONCLUSION: This kind of calcium phosphate glass ceramics can be a candidate of the carrier materials used as long term drug therapy after osteotomy surgery.

Biocompatible Materials↗