Shear bond strength of resin modified glass ionomer cement bonded to different tooth-colored restorative materials.

J Contemp Dent Pract. 2007;8(2):25-34

Authors: Taher NM, Ateyah NZ

AIM: The aim of this study was to determine in vitro the shear bond strength (MPa) and the type of bond failure when resin-modified glass ionomer cement (RMGIC) was bonded with different tooth-colored restorative materials. METHODS AND MATERIALS: The RMGIC tested was Fuji II LC (FL) and the tooth-colored restorative materials used were composite resin Point-4 (P4), Compomer Dyract AP (DY), and Ormocere Admira (AD). A total number of 60 FL specimens were prepared using Teflon molds. The specimens were divided into six equal groups. Each group of ten specimens was bonded to a tested tooth-colored restorative material as follows: Group I--etched FL bonded to P4; Group II--non-etched FL bonded to P4; Group III--etched FL bonded to DY; Group IV--non-etched FL bonded to DY; Group V--etched FL bonded to AD; and Group VI--non-etched FL bonded to AD. The specimens were stored in distilled water at 37 degrees C for 24 hours. The shear bond strength was measured in a universal testing machine, and the fractured surfaces were examined under a stereomicroscope. RESULTS: The results of the shear bond strength indicated the lowest mean value (14.46 MPa) was in Group III, and this was significantly different from the values of other groups (p<0.05). However, Groups V and VI recorded the highest mean values (24.5 MPa and 28.39 MPa) which were significantly different (p<0.05) when compared to other groups. Groups I, II, and IV showed no significant difference with mean values of 20.06, 19.99, and 20.1 MPa which were significantly different from other groups (p<0.05). CONCLUSION: AD showed the highest shear bond strength to RMGIC. All groups demonstrated a cohesive failure in FL except for Group IV where a cohesive failure in DY was recorded. AD showed good shear bond strength when laminated with FL.

PMID: 17277824 [PubMed - indexed for MEDLINE]

Effects of repeated fluoride varnish application on different restorative surfaces.

J Contemp Dent Pract. 2006 Nov 1;7(5):54-61

Authors: Salama FS, Schulte KM, Iseman MF, Reinhardt JW

AIM: The aim of this study was to assess the effect of repeated (twice) applications of two fluoride varnishes (Duraflor and CavityShield) on the surface micromorphology of a high-viscosity glass ionomer (Fuji IX GP), a compomer (F2000), and a flowable composite (Filtek Flow) using a profilometer and scanning electron microscope (SEM). METHODS AND MATERIALS: Fifteen specimens were prepared from each material, surface roughness (Ra) was measured with a profilometer, and an impression was made for epoxy replicas. The fluoride varnishes were applied to the experimental specimens of each material at repeated intervals of 48 hours. For all specimens, Ra was measured and SEM replicas were examined. RESULTS: The final Ra of glass ionomer was 3.49 +/- 0.59 (mean +/- SD) for CavityShield, 4.69 +/- 1.33 for Duraflor, and 2.96 +/- 1.53 for the controls. The final Ra of flowable composite was 0.53 +/- 0.20 for CavityShield, 2.61 +/- 3.08 for Duraflor, and 0.15 +/- 0.09 for controls. For glass ionomer and flowable composite, Duraflor was associated with a significantly higher roughness at the final measurement compared to controls (P < 0.05). SEM micrographs showed differing surface topographies which in many specimens confirmed Ra analysis. CONCLUSION: Fuji IX GP and Filtek Flow showed significantly higher roughness after two applications of Duraflor compared to controls.

PMID: 17091140 [PubMed - indexed for MEDLINE]

Effect of different bonding conditions on the shear bond strength of two compomers to bovine dentin.

J Contemp Dent Pract. 2006 Sep 1;7(4):9-16

Authors: Al-Nahedh H, Ateyah NZ

AIM: Despite the improvements to compomer materials, the bond strength of these materials remains inferior to "composite/resin bonding" systems and limits their clinical use. The purpose of this study was to evaluate the effect of acidic conditioning with phosphoric acid and Prompt L-Pop (PLP) on the shear bond strength of two compomers Dyract AP (DAP) and Composan Glass (CG) to dentin. METHODS AND MATERIALS: Sixty extracted bovine teeth were used to test the shear bond strength of two compomers to flat dentin labial surfaces. The dentin specimens were randomly assigned to six groups of ten specimens each: Group 1: DAP and Prime & Bond NT (PBNT); Group 2: DAP/PBNT with a 15 second dentin etch prior to bonding; Group 3: DAP placed with PLP adhesive; Group 4: CG and Compobond NE (CBNE); Group 5: CG/CBNE with a 15 second dentin etch; and Group 6: CG placed with PLP adhesive. The specimens were stored at 37 masculineC with 100% humidity for 24 hours then mounted and sheared using an Instron Universal Testing Machine at a cross head speed of 0.5 mm/min. The results were recorded in Mega Pascals (MPa). The sheared specimens were examined under a light microscope, and the type of failure (adhesive, cohesive, or mixed) was recorded. RESULTS: The mean dentin shear bond strength value (MPa) for the groups was: Group 1 (11.6+/-3.9); Group 2 (13.2+/-3.3); Group 3 (12.4+/-2.0); Group 4 (13.0+/-4.3); Group 5 (19.3+/-3.7); and Group 6 (13.1+/-3.0). One way analysis of variance (ANOVA) and Tukey HSD post-hoc tests detected a significantly higher bond strength (P = 0.003) for group 5. For groups 1, 3, 4, and 6, the mode of failure was mostly adhesive. When acid etching of dentin was performed (groups 2 and 5), cohesive fracture within dentin was the predominant mode of failure. Acid etching and the use of PLP significantly reduced the number of adhesive fractures and reduced variability in the shear bond strength results. CONCLUSIONS: Acid etching significantly increased the shear bond strength of CG to dentin but did not affect DAP. The application of PLP resulted in a shear bond strength not statistically different from PBNT or CPNE. CG bond to dentin is improved with acid etching using phosphoric acid. However, PLP provided no significant improvement in the shear bond strength of DAP and CG.

PMID: 16957786 [PubMed - indexed for MEDLINE]

Effect of light-activation methods and water storage on the flexural strength of two composite resins and a compomer.

Braz Oral Res. 2006 Apr-Jun;20(2):143-7

Authors: Rodrigues Filho LE, Burger LA, Kenshima S, Bauer JR, Medeiros IS, Muench A

The present study evaluated the flexural strength of three composite resins recommended for direct esthetic restorations: a polyacid modified composite (Dyract AP), a unimodal composite resin (Filtek Z250) and a hybrid composite resin (Point 4). The variation factors, apart from the type of composite resin, were the light activation method and the water storage period. The composite resins were light-cured in continuous mode (40 s, 500 mW/cm2) or in ramp mode (0-800 mW/cm2 for 10 s followed by 30 s at 800 mW/cm2) and stored for 24 hours or 30 days in distilled water at 37 degrees C. The data were analyzed by ANOVA and Tukey test for multiple comparisons (alpha = 0.05). The composite resin Z250 presented the highest mean flexural strength (166.74 MPa) and Dyract AP presented the lowest one (129.76 MPa). The storage for 30 days decreased the flexural strength in ramp mode (24 h: 156.64 MPa; 30 days: 135.58 MPa). The light activation method alone did not lead to different flexural strength values.

PMID: 16878208 [PubMed - indexed for MEDLINE]

Evaluation of shear bond strength and SEM observation of all-in-one self-etching primer used for bonding of fissure sealants.

J Contemp Dent Pract. 2006 May 1;7(2):9-16

Authors: Al-Sarheed MA

OBJECTIVES: To evaluate and compare enamel shear bond strength of an all-in-one self-etching primer (Prompt L-Pop) to regular acid etch material when bonded to two-fissure sealant systems (Concise and Dyract Seal). METHOD AND MATERIALS: Forty newly extracted non-carious first permanent molars were embedded in a Teflon mold. The teeth were divided into four groups and each consisted of ten specimens. The bonding surfaces were treated with either Prompt L-Pop as recommended by the manufacturer or etched with phosphoric acid. After 24 hours of water storage, the specimens were evaluated for shear bond strength using an Instron testing machine. Scanning electron microscope (SEM) examinations were carried out to evaluate the failure sites of the sealants. RESULTS: The mean shear bond strengths using Prompt L-Pop were Concise: 23.46 MPa and Dyract Seal: 20.34 MPa. These values were higher than and statistically different from those of Dyract Seal (9.99 MPa) and Concise (8.85 MPa) when phosphoric acid was used. The failure was predominantly of the adhesive type. The SEM examination showed the failure of debonding was predominantly related to the type of etching systems used rather than the type of fissure sealants. CONCLUSION: The use of the all-in-one self-etching adhesive Prompt L-Pop improves the mean enamel shear bond strength of fissure sealants.

PMID: 16685290 [PubMed - indexed for MEDLINE]

Microleakage of restorative materials: an in vitro study.

J Indian Soc Pedod Prev Dent. 2006 Mar;24(1):15-8

Authors: Mali P, Deshpande S, Singh A

The present study was conducted with the aim of evaluating and comparing the microleakage of glass ionomer, composite resin and compomers. Class V cavities were made in thirty intact caries free premolars and restored with restorative materials to be tested respectively. The teeth were thermocycled and subjected to silver nitrate dye penetration. They were subsequently sectioned buccolingually. Microleakage was evaluated under a stereomicroscope and data subjected to statistical analysis. The study concluded that microleakage was evident in all restorative materials, with glass ionomer showing maximum leakage followed by composite resin. Compomer demonstrated the best results with minimum leakage.

PMID: 16582525 [PubMed - indexed for MEDLINE]

The two-year clinical performance of esthetic restorative materials in noncarious cervical lesions.

J Am Dent Assoc. 2005 Nov;136(11):1547-55

Authors: Onal B, Pamir T

BACKGROUND: Materials used in restoration of cervical lesions include resin-modified glass ionomer cements, polyacid-modified resin-based composites and resin-based composites. In this study, the authors evaluated the clinical performance of these materials over a two-year period. METHODS: Thirty patients were enrolled in this study. The authors placed in these patients 130 restorations, 24 of which were Vitremer (3M Dental Products, St. Paul, Minn.), 38 were F2000 Compomer (3M Dental Products), 46 were Dyract AP (Dentsply DeTrey, Konstanz, Germany) and 22 were Valux Plus (3M Dental Products). Enamel margins were not beveled, and no mechanical retention was placed. Two independent, calibrated examiners evaluated the restorations baseline and at one and two years after placement using modified U.S. Public Health Service criteria. RESULTS: Retention rates at the end of two years were 100 percent for Vitremer, 67 percent for F2000 Compomer, 68 percent for Dyract AP and 70 percent for Valux Plus. The retention rate of Vitremer was significantly higher than that of the others (P < .05). In other categories, however, Valux Plus had the most favorable performance (P < .05). No secondary caries was detected around any restoration. CONCLUSION: Vitremer, with its high retention rate, seems to be the most appropriate material for restoration of noncarious cervical lesions, though it does not have the esthetic properties of resin-based composites. All materials used in this study were in need of improvements. CLINICAL IMPLICATIONS: Resin-modified glass ionomer cement, polyacid-modified resin-based composite and resin-based composite behaved differently in the restoration of noncarious cervical lesions. Therefore, clinicians should take factors such as esthetic needs and localization into account in selecting materials for such restorations.

PMID: 16329418 [PubMed - indexed for MEDLINE]

The color differences between different thicknesses of resin veneered over amalgam.

J Contemp Dent Pract. 2005 Nov 15;6(4):38-45

Authors: Al-Jazairy YH, El-Hejazi AA

STATEMENT OF PROBLEM: Composites and compomers are popular in dental practice. However, little is known about their esthetic appearance as veneering restorative materials over amalgam restorations. PURPOSE: This in vitro study was designed to assess the color differences of composite and compomer restorative materials, placed in thicknesses of 1 mm and 2 mm over amalgam. MATERIAL AND METHODS: Thirty six cylindrical Teflon molds were filled with amalgam (13 mm diameter, 2 mm thickness) and stored at 37 degrees C and 100% relative humidity for 7 days. Nine veneers (for each thickness of 1 and 2 mm) were fabricated from four types of tooth-colored restorative material, Dyract AP (DYR), Compoglass F (COMP), Herculite XRV (XRV), and Vitalecense (VIT), over amalgam specimens using Teflon-split molds and following the manufacturers' instructions. A spectrophotometer was used to measure the color difference DeltaE* between the two thicknesses. RESULTS: Color difference DeltaE* values for 1 mm thickness veneers [XRV (2.52), Comp (5.46), VIT (6.73), and DYR (6.88)] were statistically significantly higher than the 2 mm thickness [XRV (1.32), Comp (3.24), VIT (4.89), and DYR (4.83)]. Although the XRV material had the lowest DeltaE* values, no statistically significant difference was found between the two thicknesses. The color measurements at L*, a*, and b* showed most materials became darker in color at either thickness. CONCLUSION: The thicker veneer specimens were found to be closer in color to the controls than the thinner specimens. Only XRV had color differences (DeltaE*) small enough to be considered clinically acceptable (2.52 and 1.32 at 1 mm and 2 mm, respectively). CLINICAL IMPLICATIONS: In this in vitro study the color of XRV was affected the least when veneered on amalgam. Opaquers may be needed to be used with thinner veneers to minimize the effect of amalgam background.

PMID: 16299605 [PubMed - indexed for MEDLINE]

An investigation into the use of two polyacid-modified composite resins (compomers) and a resin-modified glass poly(alkenoate) cement used to retain orthodontic bands.

Eur J Orthod. 2005 Jun;27(3):245-51

Authors: Williams PH, Sherriff M, Ireland AJ

The aim of this investigation was to determine the effectiveness of a conventional glass poly(alkenoate) cement (Intact) and newer polyacid-modified composite resin cements (Transbond Plus and Ultra Band-Lok) to retain orthodontic bands.In the in vitro part of this study, stainless steel bands were cemented to 240 extracted third molar teeth in three test groups comprising Intact, Transbond Plus and Ultra Band-Lok. The force to deband (N) for all three cements was recorded using an Instron universal testing machine after the following observation periods: 20 minutes and 3, 6 and 12 months. The results indicated that all three cements increased their median force to deband after 12 months. Of the two compomers, Transbondtrade mark Plus demonstrated the highest median force to deband at all four time intervals.In the in vivo part of the study, 30 patients participated in a randomized cross-mouth clinical trial where the molar bands were cemented in place using either Intact or Transbond Plus. Ultra Band-Lok was not used in the clinical part of the study. The results showed there to be no clinically significant difference in band failure rates between the two cements. When patients were asked to score each for taste, there was a significant difference, with the glass poly(alkenoate) cement (Intact) being more acceptable than the polyacid-modified composite Transbond Plus (P < 0.001).No significant differences were observed in the in vitro median force to deband or in vivo band failure rates between the glass poly(alkenoate) cement and the polyacid-modified composite resins. The choice of cementing agent can therefore be made on patient factors, e.g. taste, or operator factors, e.g. ease of handling, cost and shelf life.

PMID: 15947223 [PubMed - indexed for MEDLINE]

The weight change of various light-cured restorative materials stored in water.

J Contemp Dent Pract. 2005 May 15;6(2):72-9

Authors: Keyf F, Yal&#xE7;in F

This study investigated weight changes of seven different light-cured composite restorative materials, one polyacid glass ionomer compomer, and one light-cured glass-ionomer cement following short-term and long-term storage in water. Two packable composites, three universal (hybrid) composites, one microglass composite, one polyacid glass ionomer resin composite (compomer), one microhybrid low-viscosity (flowable) composite, and one light cured glass ionomer composite cement were evaluated in this study. The weight changes of these specimens were measured daily (short-term storage), and they were measured after six weeks (long-term storage) using an electronic analytical balance. A significant difference was found in Ionoliner, Dyract AP, Opticor flow, Charisma, and Solitare 2, but no significant difference was found in the others (Filtek Z 250, Filtek P60, TPH Spectrum, and Valux Plus). Weight change showed a tendency to increase with the time of water storage. The greatest weight change occurred in light-cured glass ionomer composite cement (Ionoliner), which is followed in order by the weight changes in Dyract AP, Opticor Flow, Charisma, Solitare 2, Filtek Z250, Filtek P60, TPH Spectrum; Valux Plus had the least amount of change.

PMID: 15915206 [PubMed - indexed for MEDLINE]

The effect of bleaching agents on the surface hardness of tooth colored restorative materials.

J Contemp Dent Pract. 2005 May 15;6(2):18-26

Authors: Taher NM

AIM OF THE STUDY: The aim of this study was to evaluate the effect of at-home (Opalesence/Dr. kit 15%, Ultradent, Products, Inc. South Jordan, UT, USA) and in-office (Superoxol 35%, Sultan Chemists, Inc., Englewood, NJ, USA) bleaching on the surface hardness of the following tooth colored restorative materials: composite resin, Point-4 (P4), Kerr Corporation, Orange, CA, USA; ormocer, Admira (AD),VOCO, Germany; compomer Dyract AP (DY), Dentsply DeTrey GmbH, Germany; and resin modified glass ionomer cement, Fuji II LC (FL), GC Corporation, Japan. METHODOLOGY: Sixty specimens were prepared; 15 specimens of each material (each group n = 5, control after 15 days, at-home and in-office). All specimens were stored in distilled water at room temperature for 24 hrs before testing. A universal testing machine (Micromet 2100 series micro hardness testers) was used for testing Vicker's surface hardness for the three groups for every tested material. All results were statistically analyzed with one way analysis of variance (ANOVA), Post hoc Tukey HSD tests (P < 0.05), and percentage changes for Tukey. RESULTS: All the tested materials showed an increase in Vicker's surface hardness between base line (24 hrs) and the control group after 15 days storage in distilled water except DY which showed a decrease in surface hardness. All tested materials showed a decrease in surface hardness from control group after 15 days and both at-home and in-office bleaching agents except DY which showed increased values. SIGNIFICANCE: At-home as well as in-office bleaching agents have a softening effect on some tooth colored restorative material, and the patient must be aware before using them.

PMID: 15915201 [PubMed - indexed for MEDLINE]

An ex vivo evaluation of resin-modified glass polyalkenoates and polyacid-modified composite resins as orthodontic band cements.

J Orthod. 2004 Dec;31(4):323-8; discussion 301-2

Authors: Knox J, Chye KY, Durning P

OBJECTIVES: The objective of this ex vivo study was to assess the use of resin-modified glass polyalkenoates and polyacid-modified composite resins, as orthodontic band cements. MATERIALS AND METHOD: Plain stainless steel bands were cemented to 350 human extracted third molar teeth using 1 of 7 different cements. Following complete cement cure, half of each sample group was exposed to mechanical stress in a ball mill. Stressed and unstressed samples were tested in tension and the stress at which initial cement failure recorded. The mode of failure was recorded using an adhesive remnant evaluation. RESULTS: The mean band retention stresses offered by the cements studied ranged from 0.96 to 1.56 MPa. Fuji Ortho provided the highest mean band retention stress in "stressed" (1.56 MPa) and "unstressed" (1.45 MPa) states. Exposure to mechanical stress did not appear to significantly influence band retention or mode of cement failure for most cements. Fuji Ortho cement recorded the highest Weibull modulus for all cements tested. Virtually all samples failed at either the cement/enamel or cement band interface. CONCLUSIONS: Significant differences in band displacement stress values and mode of failure were demonstrated between the cements studied. However, generic comparisons were difficult to make.

PMID: 15608348 [PubMed - indexed for MEDLINE]

Surface hardness properties of resin-modified glass ionomer cements and polyacid-modified composite resins.

J Contemp Dent Pract. 2004 Nov 15;5(4):42-9

Authors: Bayindir YZ, Yildiz M

In this study the top and bottom surface hardness of two polyacid-modified composite resins (PMCRs), one resin-modified glass ionomer cement (RMGIC), and one composite resin were evaluated. The affect of water storage on their hardness was also investigated. The study was conducted using four different groups, each having five specimens obtained from fiberglass die molds with a diameter of 5 mm and a height of 2 mm. Measurements were made on the top and bottom surface of each specimen and recorded after 24 hours and again at 60 days. All tested materials showed different hardness values, and the values of top surfaces of the specimens were found to be higher than the bottom surface in all test groups. There was no statistical difference in the Vickers hardness (HV) values when the test specimens were kept in water storage. In conclusion Hytac displayed microhardness values higher than Vitremer and Dyract. We found the order of HV values to be Surfil > Hytac > Dyract > Vitremer, respectively. Vitremer presented the lowest microhardness level and Surfil the highest.

PMID: 15558089 [PubMed - indexed for MEDLINE]

[Observation of the clinical effects of two kinds of resin materials for restoring the defects of maxillary incisor]

Shanghai Kou Qiang Yi Xue. 2004 Aug;13(4):353-4

Authors: Cheng PH, He GR

To analyse and compare the effects of the resin materials of etched and nonetched groups in restoring the defect of maxillary incisor. 120 teeth were divided into two groups and filled by two kinds of materials. One year follow up results was studied. The effects of retention had no significant difference between the two groups, but the nonetched group had a lower stimulation to the pulp than the other one in restoring middle to deep caries. Compared to the etched group, the nonetched materials of resin has lower stimulation to pulp, more adhesion and higher success rate.

PMID: 15349689 [PubMed - indexed for MEDLINE]

Water-dependent interfacial transition zone in resin-modified glass-ionomer cement/dentin interfaces.

J Dent Res. 2004 Aug;83(8):644-9

Authors: Tay FR, Sidhu SK, Watson TF, Pashley DH

The function of the interfacial transition zone (absorption layer) in resin-modified glass-ionomer cements bonded to deep dentin remains obscure. This study tested the hypotheses that the absorption layer is formed only in the presence of water derived from hydrated dentin and allows for better bonding of resin-modified glass-ionomer cements to dentin. Ten percent polyacrylic acid-conditioned, hydrated, and dehydrated deep dentin specimens were bonded with 2 resin-modified glass-ionomer cements and sealed with resins to prevent environmental water gain or loss. A non-particulate absorption layer was identified over hydrated dentin only, and was clearly discernible from the hybrid layer when bonded interfaces were examined with transmission electron microscopy. This layer was relatively more resistant to dehydration stresses, and remained intact over the dentin surface after tensile testing. The absorption layer mediates better bonding of resin-modified glass-ionomer cements to deep dentin, and functions as a stress-relieving layer to reduce stresses induced by desiccation and shrinkage.

PMID: 15271975 [PubMed - indexed for MEDLINE]

In vivo and in vitro permeability of one-step self-etch adhesives.

J Dent Res. 2004 Jun;83(6):459-64

Authors: Chersoni S, Suppa P, Grandini S, Goracci C, Monticelli F, Yiu C, Huang C, Prati C, Breschi L, Ferrari M, Pashley DH, Tay FR

Adhesive dentistry should effectively restore the peripheral seal of dentin after enamel removal. We hypothesize that non-rinsing, simplified, one-step self-etch adhesives are effective for minimizing dentin permeability after tooth preparation procedures. Crown preparations in vital human teeth were sealed with Adper Prompt, Xeno III, iBond, or One-Up Bond F. Epoxy resin replicas were produced from polyvinyl siloxane impressions for SEM examination. Dentin surfaces from extracted human teeth were bonded with these adhesives and connected to a fluid-transport model for permeability measurements and TEM examination. Dentinal fluid droplets were observed from adhesive surfaces in resin replicas of in vivo specimens. In vitro fluid conductance of dentin bonded with one-step self-etch adhesives was either similar to or greater than that of smear-layer-covered dentin. TEM revealed water trees within the adhesives that facilitate water movement across the polymerized, highly permeable adhesives. Both in vitro and in vivo results did not support the proposed hypothesis.

PMID: 15153452 [PubMed - indexed for MEDLINE]

In vitro inhibition of caries-like lesions with fluoride-releasing materials.

J Oral Sci. 2004 Mar;46(1):45-50

Authors: Yaman SD, Er O, Yetmez M, Karabay GA

The aim of this study was to compare the in vitro caries inhibition of various resin-based materials. Class V cavities were prepared in twenty-five freshly extracted human premolar teeth which were then restored with glass-ionomer cement (Chemfill II), compomer (Compoglass F, Dyract AP) and composite resin (Tetric Ceram and Z 100). The teeth were submerged in an acid gel for 6 weeks. Each specimen was sectioned. These sections were left in water for 24 hours, and then examined using polarized light microscopy. The lesion consisted of two parts, the outer surface lesion and the cavity wall lesion. There was no significant difference in the body depth of the outer lesion and in the depth of the wall lesion among teeth restored with Compoglass F, Dyract AP and Chemfill II (P > 0.05). There was a significant difference between those restored with Z 100 and Tetric Ceram (P < 0.05). The length of the wall lesion for the teeth restored with Chemfill II was significantly smaller than that in the remaining groups (P < 0.05). The length of the wall lesion for teeth restored with Tetric Ceram and Z 100 was significantly higher than in the remaining groups (P < 0.05). These results suggest that composite materials and compomer provide less caries inhibition than glass-ionomer cements.

PMID: 15141723 [PubMed - indexed for MEDLINE]

Direct restorative materials. What goes where?

J Am Dent Assoc. 2003 Oct;134(10):1395-7

Authors: Christensen GJ

The many tooth-colored restorative materials available today present a confusing array of products. However, they are the best group of tooth-colored restorative materials available in dentistry to date. Dentists are advised to learn the characteristics of each category of tooth-colored materials and to base their judgment of which type to use on an in-depth consideration of the many products available.

PMID: 14620021 [PubMed - indexed for MEDLINE]

Effect of prophylactic treatments on the superficial roughness of dental tissues and of two esthetic restorative materials.

Pesqui Odontol Bras. 2003 Jan-Mar;17(1):63-8

Authors: Salami D, Luz MA

Dental prophylaxis is a common way to remove dental plaque and stain, both undesirable factors in most dentistry procedures. However, besides cleaning the tooth surface, prophylactic techniques may increase the surface roughness of restorations and dental tissues, which, in turn, may result in plaque accumulation, superficial staining and superficial degradation. This study evaluated the effect of three prophylactic techniques--sodium bicarbonate jet, pumice paste and whiting paste--on the superficial roughness of two restorative materials--a composite resin and a compomer--and on the superficial roughness of two dental surfaces--enamel and cementum/dentin--through rugosimetric and scanning electron microscopy (SEM) analysis. Statistical analysis of the rugosimetric data showed that the use of pumice paste on enamel produced a significantly smoother surface than the natural surface. However, comparing the effect of the three techniques, prophylaxis with the pumice paste produced a rougher surface than did the other techniques as regards enamel and cementum/dentin probably due to its abrasiveness. On composite resin, the pumice paste only produced a rougher surface than did the whiting paste. On compomer, all of the applied treatments produced similar results. Based on rugosimetric and SEM analysis, we could conclude that the prophylactic treatments employed did not improve roughness of the studied surfaces. As to the effects of the techniques, they were different depending on the surfaces on which the prophylactic treatments were applied.

PMID: 12908062 [PubMed - indexed for MEDLINE]

In vivo evaluation of two new moisture-resistant orthodontic adhesive systems: a comparative clinical trial.

J Orthod. 2003 Jun;30(2):139-47; discussion 127-8

Authors: Mavropoulos A, Karamouzos A, Kolokithas G, Athanasiou AE

OBJECTIVE: To evaluate and compare the clinical performance of two new moisture-resistant orthodontic adhesive systems: a chemically-cured composite resin (Unite, 3M Unitek, Monrovia, California, USA) in conjunction with a special moisture-resistant primer (Transbond MIP, 3M Unitek, Monrovia, California, USA); and a fluoride-releasing light-cured compomer (Assure, Reliance Orthodontic Products, Inc., Itasca, Illinois, USA). DESIGN: Randomized controlled clinical trial using the 'split-mouth' technique. SETTING: Department of Orthodontics, Aristotle University of Thessaloniki. Subjects (Materials) and Methods: Twenty-five consecutively started patients (13 females and 12 males) requiring fixed appliance orthodontic treatment. INTERVENTIONS: Four-hundred-and-thirty-six stainless steel brackets bonded to all teeth except molars using two different moisture-resistant orthodontic adhesive systems. MAIN OUTCOME MEASURES: Bond failure rates during a period of 9 months were estimated for each adhesive system and the corresponding bracket survival curves were plotted using the Kaplan- Meier product-limit estimate. Bracket survival distributions with respect to adhesive material, tooth location, patient's gender and operator, were then compared by means of a log-rank test. Bond failure interface was determined using the Adhesive Remnant Index. RESULTS: Assure recorded a higher bond failure rate (13.8 per cent) than Unite & MIP (7.3 per cent). The corresponding bracket survival curves were found to be significantly different (P < 0.05). Premolars exhibited higher bond failures than incisors and canines (P < 0.001), while half (49.8 per cent) of the total bond failures occurred during the first 2 months of treatment. The predominant mode of failure was within the bonding material. CONCLUSION: The new moisture-resistant adhesive systems under study were found to be clinically efficient, though Assure exhibited a significantly higher bond failure rate than Unite and Transbond MIP. The higher frequency of adhesive failures observed with Assure might indicate a possible weak point at the adhesive-bracket interface.

PMID: 12835430 [PubMed - indexed for MEDLINE]

Effects of fluoride and aluminum from ionomeric materials on S. mutans biofilm.

J Dent Res. 2003 Apr;82(4):267-71

Authors: Hayacibara MF, Rosa OP, Koo H, Torres SA, Costa B, Cury JA

Ionomeric materials release different proportions of fluoride and aluminum. Their simultaneous effect on the acidogenicity and composition of S. mutans biofilm is unknown. Six cylindrical specimens of each material (Ketac-fil, Vitremer, Fuji-Ortho LC, F-2000, and Z-100) were incubated with S. mutans GS-5 in culture media containing 5% sucrose (w/v). The media were changed daily for seven days, during which the pH and concentrations of fluoride and aluminum were determined. Furthermore, the concentrations of these ions and insoluble polysaccharide were determined in the biofilm formed at the end of the experimental period. The results showed that all the materials tested released fluoride. However, Vitremer released the highest amount of aluminum and was the most effective in reducing the acidogenicity of S. mutans biofilms. It also significantly affected both biofilm formation and composition. Thus, this study suggests that aluminum released by ionomeric materials may enhance the biological effects of fluoride.

PMID: 12651929 [PubMed - indexed for MEDLINE]

The effect of different drying methods for single step adhesive systems on microleakage of tooth colored restorations.

J Contemp Dent Pract. 2003 Feb 15;4(1):1-9

Authors: Owens BM

The purpose of this in vitro study was to evaluate microleakage of tooth colored restoratives and accompanying single step adhesive systems using two drying methods (syringe air versus "sponge" applicator blotting). Eighty teeth were randomly assigned to four material groups. Class V cavity preparations, located half in enamel and half in cementum at the cementoenamel junction (CEJ), with a 1.0 mm enamel bevel were completed. The adhesive/composite groups included: (1) Single-Bond/Z-100 Composite, (2) Prime & Bond 2.1/Dyract AP Compomer, (3) OptiBond Solo Plus/Prodigy Composite, and (4) Scotchbond MultiPurpose/Z-100 Composite. Each material group (n=20), consisted of preparation Subgroups dried with syringe air (A), (n=10) and sponge applicators (B), (n=10). The preparations were conditioned, rinsed, and gently dried followed by placement of the primer/adhesive and restorative materials. All teeth were thermocycled, stained with methylene blue dye, invested in clear acrylic resin, and sectioned longitudinally through the center of the restoration. Readings were taken at the occlusal and gingival surface positions of each restoration section. A ratio (%) of wall length to amount of leakage along each wall was established. One-way Analysis of Variance (ANOVA) testing revealed: (1) no significant (p<0.05) differences existed between materials at the occlusal surface position in Subgroups A and B (syringe vs. applicator drying), (2) significantly (P<0.05) greater leakage of OptiBond Solo Plus compared to Single-Bond, Prime & Bond 2.1, and Scotchbond MultiPurpose at the gingival surface position in Subgroups A and B, (3) significantly (p<0.05) greater leakage of OptiBond Solo Plus compared to Single-Bond and Scotchbond MultiPurpose, combining the occlusal/gingival surface position scores, (4) no significant difference existed between Single-Bond Subgroups A/B, OptiBond Solo Plus Subgroups A/B, Scotchbond MultiPurpose Subgroups A/B, (5) significantly (p<0.05) greater leakage of Prime & Bond 2.1 Subgroup B compared to Subgroup A, (6) no significant (p<0.05) difference existed between material groups, except OptiBond Solo Plus (occlusal vs. gingival surface position), (7) no significant (p<0.05) difference between Single-Bond, OptiBond Solo Plus, and Scotchbond MultiPurpose comparing both Subgroups, same materials, and surface positions, and (8) no significant (p<0.05) difference existed between Prime & Bond 2.1, comparing both Subgroups, occlusal surface position. In the present study, significantly greater leakage was revealed with OptiBond Solo Plus compared to the other material groups, especially at the gingival surface positions. Significantly greater leakage was also recorded with OptiBond Solo Plus and Prime & Bond 2.1 sponge applicator drying as compared to the same materials, syringe air drying.

PMID: 12595929 [PubMed - indexed for MEDLINE]

Clinical performance of a compomer and amalgam for the interproximal restoration of primary molars: a 24-month evaluation.

Br Dent J. 2002 Sep 28;193(6):339-42

Authors: Duggal MS, Toumba KJ, Sharma NK

OBJECTIVES: To evaluate the clinical performance of a compomer material (Dyract) in comparison with dental amalgam (Contour) for management of proximal caries in primary molars in young children. SETTING: General dental practice, and a dental hospital paediatric clinic. METHOD: This was a prospective study. A split mouth design was used with identical pairs of minimal Class II cavities, of matched tooth type in the same dental arch, usually diagnosed with the use of bitewing radiographs. Seventy-eight pairs of restorations were completed of which 60 pairs were available for evaluation after 24 months. RESULTS: Comparable retention rates were observed for both Dyract and amalgam. The retention rates were high for both materials, with only four amalgam and two Dyract restorations failing over 24 months. Significantly better marginal integrity (P < 0.05) was observed for Dyract compared with amalgam with no significant differences between the two materials for recurrent caries, wear or surface texture. CONCLUSIONS: Dyract seemed to be a suitable alternative to amalgam for proximal restorations in primary molars of young children for use in general dental practice.

PMID: 12368893 [PubMed - indexed for MEDLINE]

Orthodontic adhesives: a systematic review.

J Orthod. 2002 Sep;29(3):205-10; discussion 195

Authors: Mandall NA, Millett DT, Mattick CR, Hickman J, Worthington HV, Macfarlane TV

OBJECTIVES: To evaluate which orthodontic adhesives (a). bond orthodontic brackets to teeth more reliably and (b). are more effective at preventing decalcification. DATA SOURCES: The search strategy for the literature review was carried out according to the standard Cochrane systematic review methodology. The Cochrane Clinical Trials Register and the Cochrane Oral Health Group Specialized Register were searched for randomized clinical trials and controlled clinical trials. All volumes that had not already been assessed by the Oral Health Group in the European Journal of Orthodontics, American Journal of Orthodontics, Journals of Orthodontics, and Angle Orthodontist were hand-searched. Inclusion and exclusion criteria were applied when considering the studies to be included in this review. DATA SELECTION: The primary outcome measure was the failure of the orthodontic adhesive. A secondary outcome of decalcification occurring around the orthodontic bracket was also recorded, if data were available. DATA EXTRACTION: Two randomized clinical trials and one controlled clinical trial were identified that fulfilled all the inclusion and exclusion criteria. The trials compared: (a). light- and chemically-cured composite; (b). chemically-cured composite and conventional glass ionomer cement; and (c). chemically-cured composite and light-cured compomer. DATA SYNTHESIS: Each paper was quality assessed by two people independently. A qualitative analysis of the trials in the review is presented. The data presentation, for the majority of the trials, precluded the use of suggested Cochrane Health Group statistical analysis. CONCLUSIONS: It is difficult to draw any conclusions from this review; however, suggestions are made for methods of improving future research involving orthodontic adhesives.

PMID: 12218198 [PubMed - indexed for MEDLINE]

Infrared spectrometric study of acid-degradable glasses.

J Dent Res. 2002 Aug;81(8):552-5

Authors: De Maeyer EA, Verbeeck RM, Vercruysse CW

The composition of glasses used in glass-ionomer cements affects their leaching behavior and hence the properties of the cement. The aim of this study was to correlate the composition and leaching behavior of these glasses with their infrared absorption characteristics. The wavenumber of the absorption band of the Si-O asymmetric stretching vibration shifts to a higher value with decreasing content of mono- and bivalent cations in the glass. This effect can be ascribed to the influence of these extraneous ions on the glass network order and connectivity. Preferential leaching of these ions induces an increase of asymmetric stretching vibration and a general modification of the band profile. The results can be correlated with the x-ray diffraction characteristics of the glass.

PMID: 12147746 [PubMed - indexed for MEDLINE]

The glass-ionomer phase in resin-based restorative materials.

J Dent Res. 2001 Sep;80(9):1808-12

Authors: Tay FR, Pashley EL, Huang C, Hashimoto M, Sano H, Smales RJ, Pashley DH

Glass-ionomer (GI) fillers are added to restorative materials, but it is unclear if they truly react with these materials. This TEM study evaluated the existence of the GI phase in a conventional GIC (ChemFlex), a resin-modified GIC (Fuji II LC), a giomer (Reactmer Paste), a compomer (Dyract AP), and a composite (SpectrumTPH), before and after water uptake. Wafers were stored at 100% RH for 24 hrs, or in water for 7 or 84 days. ChemFlex glass particles were surrounded by 300-nm-thick silica gel layers. In Fuji II LC, we found thinner hydrogel layers (100 nm) that became thicker upon water storage. No appreciable change occurred in Reactmer Paste. Only a very thin hydrogel layer occurred in Dyract AP, and none was seen in SpectrumTPH after water storage for 84 days. We conclude that the variable extent of the GI phase is determined by differences in the resin composition of the restoratives.

PMID: 11926238 [PubMed - indexed for MEDLINE]

The extent to which resin can infiltrate dentin by acetone-based adhesives.

J Dent Res. 2002 Jan;81(1):74-8

Authors: Hashimoto M, Ohno H, Kaga M, Sano H, Endo K, Oguchi H

The combined methodologies of fractography and laser-Raman spectroscopic analysis were used for evaluation of the resin-dentin bonds made with wet and dry bonding. Resin-dentin-bonded beams were produced by means of 2 acetone-based adhesives (One-Step and Prime & Bond NT). The micro-tensile bond test was conducted, and the fractured surfaces of all specimens were examined by SEM and an image analyzer. The amount of resin infiltration within the hybrid layer was quantified by means of a laser-Raman spectroscope. In Raman analysis, the amount of resin impregnation within the hybrid layer of the dry bonding was found to be significantly lower (approximately 50%) than that in the wet one. Under fractographic analysis, a correlation was found between the bond strength and the failure mode. Based on those findings, it was suggested that the integrity between the bonding resin and the top of the hybrid layer played a major role in bond strength.

PMID: 11820372 [PubMed - indexed for MEDLINE]

X-ray diffraction study of acid-degradable glasses.

J Dent Res. 2001 Aug;80(8):1764-7

Authors: De Maeyer EA, Verbeeck RM

The composition of the degradable glasses used in commercial dental glass-ionomer cements determines their leaching behavior and hence the properties of the cement. The objective of the present study was to assess if the composition and leaching in acetic acid solutions are reflected in the x-ray diffraction characteristics of these glasses. The position (2theta) of the maximum of the first sharp diffraction peak shifts to higher diffraction angles with increasing number and ionic radius of mono- and bivalent cations in the glass. Upon acid-leaching, these ions are preferentially leached out, so that (2theta) decreases. These results can be related to the decreasing Si-Si distance in the glass network with increasing modifier radius.

PMID: 11669490 [PubMed - indexed for MEDLINE]

Fatigue of restorative materials.

Crit Rev Oral Biol Med. 2001;12(4):350-60

Authors: Baran G, Boberick K, McCool J

Failure due to fatigue manifests itself in dental prostheses and restorations as wear, fractured margins, delaminated coatings, and bulk fracture. Mechanisms responsible for fatigue-induced failure depend on material ductility: Brittle materials are susceptible to catastrophic failure, while ductile materials utilize their plasticity to reduce stress concentrations at the crack tip. Because of the expense associated with the replacement of failed restorations, there is a strong desire on the part of basic scientists and clinicians to evaluate the resistance of materials to fatigue in laboratory tests. Test variables include fatigue-loading mode and test environment, such as soaking in water. The outcome variable is typically fracture strength, and these data typically fit the Weibull distribution. Analysis of fatigue data permits predictive inferences to be made concerning the survival of structures fabricated from restorative materials under specified loading conditions. Although many dental-restorative materials are routinely evaluated, only limited use has been made of fatigue data collected in vitro: Wear of materials and the survival of porcelain restorations has been modeled by both fracture mechanics and probabilistic approaches. A need still exists for a clinical failure database and for the development of valid test methods for the evaluation of composite materials.

PMID: 11603506 [PubMed - indexed for MEDLINE]

Restorative dentistry for pediatric teeth. State of the art 2001.

J Am Dent Assoc. 2001 Mar;132(3):379-81

Authors: Christensen GJ

PMID: 11258095 [PubMed - indexed for MEDLINE]

An ex vivo assessment of resin-modified glass ionomer bonding systems in relation to ceramic bracket debond.

J Orthod. 2000 Dec;27(4):329-32

Authors: Larmour CJ, McCabe JF, Gordon PH

This ex vivo study assessed three new resin-modified glass ionomer cements (Fuji ORTHO LC, Vitremer, and Dyract-Cem) in relation to ceramic bracket removal. It was hypothesized that the use of these cements would facilitate bracket removal and eliminate debond complications Eighty extracted premolar teeth were divided into four groups of 20 teeth and bonded with Intrigue brackets using each of the resin-modified cements (groups 1, 2, and 3), the control group 4 was bonded with Concise chemically-cured adhesive. The teeth were debonded by applying a shear load using an Instron universal testing machine. The mean force to debond was calculated for each group and each tooth was examined under the stereomicroscope to record the site of bond failure and the Adhesive Remnant Index (ARI). The results showed that the resin-modified cements were very effective at eliminating ceramic bracket debond problems. Bracket fracture was eliminated compared with a 40 per cent fracture rate with the control and the ARI scores were all reduced. The elimination of debond problems appears to be related to the significantly reduced (P < 0.001 using ANOVA and Tukey tests) mean and maximal debond forces compared with the control.

PMID: 11099572 [PubMed - indexed for MEDLINE]

Orthodontic banding cements.

J Orthod. 2000 Sep;27(3):283-4

Authors: Johnson N

PMID: 11099564 [PubMed - indexed for MEDLINE]

The need for caries-preventive restorative materials.

J Am Dent Assoc. 2000 Sep;131(9):1347-9

Authors: Christensen GJ

PMID: 10986838 [PubMed - indexed for MEDLINE]

Stoichiometry of the leaching process of fluoride-containing aluminosilicate glass-ionomer glasses.

J Dent Res. 1999 Jul;78(7):1312-8

Authors: De Maeyer EA, Verbeeck RM, Vercruysse CW

Dental glass-ionomer cements (GIC) set by an acid-base reaction between a polyalkenoic acid and an ion-leachable glass. The exact relationship between the glass composition and the setting and final properties of GIC is not yet fully elucidated. As part of a systematic study of this relationship, we studied the leaching stoichiometry of glasses used in commercial formulations to correlate the glass composition with its leaching properties. The leaching experiments were performed in acetic acid solutions at pH = 3.4 by means of a pH-stat method. After predetermined time intervals, the suspension was filtered and the filtrate was analyzed for the glass constituents. The usefulness of the pH-stat method for the determination of glass reactivity was corroborated. The deviation of the leaching stoichiometry with respect to the pure glass stoichiometry decreased with increasing relative content of mono- and bivalent glass network dwellers and modifiers. Indications were found that the latter can be leached out independently and preferentially, while the leaching of network dwellers is coupled with the aluminum release. The F content as well as the reactivity of the glass affect the amount of fluoride available for release from a set GIC. It could be concluded that the leaching stoichiometry of GIC glasses can be correlated with their absolute and relative composition.

PMID: 10403458 [PubMed - indexed for MEDLINE]

Residual monomer/additive release and variability in cytotoxicity of light-curing glass-ionomer cements and compomers.

J Dent Res. 1998 Dec;77(12):2012-9

Authors: Geurtsen W, Spahl W, Leyhausen G

In previous studies, light-cured glass-ionomer cements have been shown to evoke cytotoxic reactions. It was the purpose of this investigation (a) to determine the nature of the ingredients released into an aqueous medium from 2 light-cured glass-ionomer cements (GICs) and 3 compomers; (b) to evaluate the cytotoxicity of these extracts; and (c) to correlate the extent of the cytotoxic effects with eluted substances. Specimens of 2 light-cured GICs and 3 compomers were prepared and extracted in distilled water or cell culture medium for 24 hrs (surface-liquid ratio 42.4 mm2/mL). The aqueous eluates were analyzed by gas chromatography/mass spectrometry (GC/MS). The relative amounts of the components released from various products were compared by means of an internal caffeine standard [%CF]. For evaluation of cytotoxic effects, permanent 3T3 fibroblasts were incubated with medium extracts for 24 hrs. In addition, the ED50 concentration of the photoinitiator diphenyliodoniumchloride (DPICl) was determined. In all extracts, several water-elutable organic substances were found: (Co)monomers (especially HEMA and ethylene glycol compounds), additives (e.g., camphorquinone and diphenyliodoniumchloride), and decomposition products. The extracts of 3 products inhibited cell growth only moderately, whereas the light-cured GIC Vitrebond and the compomer Dyract Cem revealed severe cytotoxic effects. Vitrebond liberated the initiator DPICl, whereas Dyract Cem segregated a relatively high quantity [2966 %CF] of the comonomer TEGDMA in comparison with the other products. The present data show that TEGDMA and DPICl may be regarded as the prime causes for cytotoxic reactions evoked by the investigated light-cured glass-ionomer cements or compomers. Therefore, leaching of these substances should be minimized or prevented.

PMID: 9839790 [PubMed - indexed for MEDLINE]

Electrothermal bonding: shear bond strength of orthodontic brackets after two weeks.

Br J Orthod. 1998 May;25(2):123-6

Authors: Ward GJ, Mizrahi E, Cleaton-Jones PE

Electrothermal bonding is based on acceleration of the setting reaction of a bonding: resin by the selective application of heat to the orthodontic bracket through the passage of a low voltage electric current. The purpose of this study was to compare the shear bond strength of nine resins comprising chemically-cured, light-cured, and glass ionomer types, 14 days after electrothermal and conventional bonding. Mean shear and bond strengths ranged from a low of 7.4 MPa for Sequence (electrothermally bonded) to a high of 15.4 MPa Concise (control). There was no statistically significant difference between the electrothermal and conventional bonding methods. All the resins produced bond strengths adequate for clinical orthodontics at 14 days.

PMID: 9668995 [PubMed - indexed for MEDLINE]

Shear bond strengths of ceramic brackets bonded with different light-cured glass ionomer cements: an in vitro study.

Eur J Orthod. 1998 Apr;20(2):177-87

Authors: Cacciafesta V, S&#xFC;ssenberger U, Jost-Brinkmann PG, Miethke RR

The purpose of this study was to evaluate the shear bond strengths of four light-cured glass ionomer cements used for direct bonding of ceramic brackets, and to compare the results with a two-paste chemically-cured composite resin. Two commercially available polycrystalline ceramic brackets, with either chemically or mechanically retentive bracket bases, were evaluated. The brackets were bonded to 100 freshly extracted bovine incisors, and, after storage in tap water at room temperature for 24 hours, they were subsequently tested in a shear mode using a universal testing machine. The maximum bond strength and the site of bond failure were recorded. With the mechanically retentive base, Fuji Ortho LC produced the highest bond strength (18.50 MPa), which was not significantly different from the values achieved with Concise (14.88 MPa) (P > 0.1) and Photac Bond (13.86 Mpa) (P = 0.1). The lowest bond strength was provided by locomp A20 (5.23 MPa). With the chemically retentive base, the highest bond strength was measured with Concise (29.27 MPa), which was significantly (P < 0.01) higher than the values for Photac Bond (16.27 MPa) and Fuji Ortho LC (13.48 MPa). Again locomp A20 produced the lowest bond strength (3.21 MPa). Three cements (Dyract Ortho, locomp A20 and Fuji Ortho LC) provided higher shear bond strengths with the mechanical retention system, whereas Concise and Photac Bond gave higher strengths with the silane-treated bracket bases. However, the strengths were statistically significantly different only for locomp A20 (P = 0.001) and Concise (P = 0.001). With the mechanically retentive base, Dyract Ortho and locomp A20 failed at the enamel-adhesive interface, whereas Photac Bond and Concise debonded at the bracket-adhesive interface. Fuji Ortho LC failed at both, the bracket-adhesive (40 per cent) and the adhesive-enamel (60 per cent) interface. With the chemically retentive base, all the adhesives failed at the enamel-adhesive interface. Only one bracket fracture occurred in this study, and no enamel damage was detected.

PMID: 9633171 [PubMed - indexed for MEDLINE]

Clinical evaluation of compomer in primary teeth: 1-year results.

J Am Dent Assoc. 1997 Aug;128(8):1088-96

Authors: Hse KM, Wei SH

The clinical performance of the compomer Dyract (L.D. Caulk, Dentsply) was evaluated and compared with that of the hybrid composite resin Prisma TPH (L.D. Caulk, Dentsply) in restorations of 60 bilateral matched pairs of primary teeth. After 1 year, the overall failure rate for both restorative materials was 1.7 percent. There were no statistically significant differences in recurrence of caries, color matching, marginal integrity or anatomic form. The only statistically significant differences were in marginal discoloration and wear, where the compomer was inferior to the hybrid composite resin. The authors conclude that compomer is a suitable alternative to amalgam for restoring primary teeth.

PMID: 9260418 [PubMed - indexed for MEDLINE]

Comparative physico-mechanical characterization of new hybrid restorative materials with conventional glass-ionomer and resin composite restorative materials.

J Dent Res. 1997 Apr;76(4):883-94

Authors: Gladys S, Van Meerbeek B, Braem M, Lambrechts P, Vanherle G

The recently developed hybrid restorative materials contain the essential components of conventional glass ionomers and light-cured resins. The objective of this study was to determine several physical and mechanical properties of eight such materials in comparison with two conventional glass ionomers, one micro-filled, and one ultrafine compact-filled resin composite. The two resin composites and two of the three polyacid-modified resin composites could be polished to a higher gloss than the conventional as well as the resin-modified glass ionomers. After abrasion, surface roughness increased for all materials, but not at the same extent, being the least for the conventional resin composites and one polyacid-modified resin composite, Dyract. In contrast to the later resin composites, of which the surface roughness is principally determined by the presence of protruding filler particles above the resin matrix, roughness of conventional and resin-modified glass ionomers results from both protruding filler particles and intruding porosities. The mean particle size of the hybrid restorative materials fell between the smaller mean particle size of the resin composites and the larger one of the conventional glass ionomers. The micro-hardness and Young's modulus values varied substantially among all eight hybrid restorative materials. For all the resin-modified glass-ionomer restorative materials, the Young's modulus reached a maximum value one month after mixing and remained relatively stable thereafter. The Young's modulus of the conventional and the polyacid-modified resin composites decreased slightly after one month. The conventional glass-ionomer materials undoubtedly set the slowest, since their Young's modulus took six months to reach its maximum. The flexural fatigue limit of the hybrid restorative materials is comparable with that of the micro-filled composite. From this investigation, it can be concluded that the physico-mechanical properties vary widely among the eight hybrid restorative materials, indicating that these materials probably have yet to achieve their optimum properties. Their mechanical strength is inadequate for use in stress-bearing areas, and their appearance keeps them from use where esthetics is a primary concern.

PMID: 9126185 [PubMed - indexed for MEDLINE]

Compomers vs. resin-reinforced glass ionomers.

J Am Dent Assoc. 1997 Apr;128(4):479-80

Authors: Christensen GJ

PMID: 9103800 [PubMed - indexed for MEDLINE]

When to use fillers, build-ups or posts and cores.

J Am Dent Assoc. 1996 Sep;127(9):1397-8

Authors: Christensen GJ

After preliminary tooth preparation for crowns, all previously placed tooth restorative material should be removed from teeth before making final tooth preparations. Small areas of missing teeth should be replaced with fillers (compomer); larger pieces of missing teeth should be replaced with build-ups (bonded composite resin or bonded amalgam); and endodontically treated teeth with half or more of the coronal tooth structure missing should receive a titanium or titanium alloy post and core and a bonded composite resin or bonded amalgam build-up.

PMID: 8854619 [PubMed - indexed for MEDLINE]

A clinical evaluation of a resin-modified. Glass ionomer restorative material.

J Am Dent Assoc. 1995 Sep;126(9):1245-53

Authors: Barnes DM, Blank LW, Gingell JC, Gilner PP

Compomers, resin-modified glass ionomers, were developed to improve the physical properties and clinical handling of glass ionomers. Compomers can be designed to be light-activated and used as restoratives or liners. This article reports data collected up to 12 months after placement of both compomer restorations and liners and is part of an ongoing study evaluating the performance of this material. Based on this data, the authors conclude that this new generation of light-activated glass-ionomer restoratives provides clinical results comparable to those recorded for composite resins at 12 months.

PMID: 7560584 [PubMed - indexed for MEDLINE]