The effect of primers on bond strength of polyacid-modified resin composites (compomers)

This study evaluated the effect of primer on shear bond strength and marginal gaps of six new compomers immediately after light-activation. A resin-modified glass ionomer cement, a conventional glass-ionomer cement and a microfilled composite were used for comparison. The marginal gap widths of each of the four compomers and a microfilled composite used with the primer were significantly smaller compared with those used without the primer. The bond strength values of five compomers used with the primer were significantly higher than those used without the primer. The bond strength of conventional glass-ionomer was not affected by the primer (or the conditioner).     

Fluoride release/uptake of polyacid-modified resin composites (compomers) in neutral and acidic buffer solutions

The aim of the present study was to evaluate the fluoride uptake/release of polyacid-modified resin composites (compomers) in neutral and acidic buffer solutions. Two compomers (Dyract and Compoglass) were tested and the conventional glass-ionomer cement (GIC) Vivaglass Base served as a control. Forty specimens were fabricated from each of the respective materials. Twenty of these specimens were placed in artificial saliva and the other 20 specimens in a fluoridated dentifrice slurry for 5 min. Then, 10 fluoridated and 10 non-fluoridated specimens were immersed in a neutral buffer solution (pH 6.8), and the other specimens were immersed in an acidic solution (pH 4.0). After 1, 2, 3, 4, and 5 days the samples were again placed in either a fluoridated dentifrice slurry or saliva for 5 min, after which time they were transferred to fresh buffer solutions. The fluoride content of the solutions was assessed with a fluoride sensitive electrode. Fluoride release from all the materials decreased continuously during the experiment, with a significantly higher release in the acidic solution compared to the neutral buffer solution. Fluoridation did not result in an increased fluoride release for the compomers. However, the conventional GIC revealed a significantly higher fluoride release after fluoridation. It is concluded that Dyract and Compoglass can not be replenished with fluoride, irrespective of the pH value of the environment.     

Microleakage of two polyacid-modified resin composites under different conditioning methods in primary teeth

This study evaluated the effect of different conditioning methods on micro-leakage in primary teeth. Fifty-one cervical cavities were prepared on the twenty-six extracted primary molars and divided randomly into five groups. In Group I and IV phosphoric acid, in group 11 non-rinse conditioner (NRC) was applied. In group III and V no pretreatment was used. Groups I-III were restored with Prime & Bond NT and Dyract AP and Group IV-V restored with Syntac SC and Compoglass F. The restored teeth were stored for 24 hours in distilled water at 37 degrees C, immersed in 0.5 percent basic fuchsin for 24 hours. Dye penetration was determined using a stereomicroscope. The results revealed that although enamel microleakage was not affected by the conditioning method used in both restorative materials, pretreating the cavity with phosphoric acid had a positive effect on reducing the dentin microleakage compared with conditioning by NRC.     

One-year clinical evaluation of posterior packable resin composite restorations

This study evaluated the clinical performance of four packable resin composite restorative materials in posterior teeth (Class I and II) compared with one hybrid composite after one year. Eighty-four restorations were placed in 16 patients. Each patient received at least five restorations. The tested materials were: (1) Solitaire + Solid Bond; (2) ALERT + Bond-1; (3) Surefil + Prime & Bond NT (4) Filtek P60 + Single Bond and; (5) TPH Spectrum + Prime & Bond 2.1. All restorations were made using rubber dam isolation, and the cavity design was restricted to the elimination of carious tissue. Deeper cavities were covered with calcium hydroxide and/or glass ionomer cement. In shallow and medium cavities, no protection was performed except for the respective adhesive system used in each group. Each adhesive system and resin composite was placed according to the manufacturer's instructions. One week later, the restorations were finished/polished and evaluated according to the USPHS modified criteria. All patients attended the one-year recall, and the 84 restorations were evaluated at that time based on the same evaluation criteria. The scores were submitted to statistical analysis (Chi-square test, p<0.05). Solitaire and TPH showed some fractures at marginal ridges. Solitaire, ALERT and TPH showed some concerns related to color match and surface texture. Surefil and Filtek P60 showed an excellent clinical performance after one year.     

One-year clinical evaluation of composite fillings and inlays in posterior teeth

In the course of a prospectively designed long-term clinical trial, composite fillings and inlays were evaluated for clinical acceptability as restorative materials in one, two or more surface cavities of posterior teeth over a 1-year period. In 45 patients, 88 restorations were placed by nine student operators, under the supervision of an experienced dentist, to compare the two half sides using the composite resins Tetric (Vivadent), blend-a-lux (Blend-a-med), and Pertac-Hybrid Unifil (Espe). The first clini-cal follow-up check took place within a time period of 11 – 13 months after placement of the restorations using modified USPHS criteria. The interpretation of the clinical criteria showed satisfactory results over this time period: more than 85% of the inlays and direct fillings were rated ``alpha' or ``bravo', using the parameters of assessment defined in this study. Only three restorations (two fillings, one inlay), all in molars, were rated ``delta', i. e., unacceptable. The reasons for their replacement were mar-ginal opening, secondary caries, and loss of sensitivity. For the criteria ``surface texture', ``anatomical form of the surface', and ``occlusion', composite inlays were significantly better than composite fillings. These results indicate that posterior composite restorations provide acceptable and excellent clinical service, even if they are placed by relatively inexperienced student operators.     

Three-year clinical evaluation of a polyacid-modified resin composite (Dyract)

The aim of this study was to clinically evaluate a polyacid-modified resin composite (Dyract; Dentsply deTrey). Forty-one Dyract restorations were placed (36 in noncarious cervical cavities and five in anterior approximal cavities), and assessed after three years. The retention rate was 97% for the cervical restorations; however, 16 restorations showed some degree of marginal discoloration, sometimes severe. Color match and surface integrity were highly satisfactory throughout the trial. Dyract has now been superseded by Dyract AP, and the manufacturers should consider recommending mandatory enamel etching.     

Microleakage evaluation of a flowable polyacid-modified resin composite used as fissure sealant on air-abraded permanent teeth

This study evaluated the microleakage of a flowable polyacid-modified resin composite used as a fissure sealant on air-abraded teeth in comparison to a resin-based fluoride sealant. Sixty extracted human third molars were divided into six subgroups (n = 10) under two main groups (fissure sealant materials). The occlusal surfaces of the teeth were air-abraded at 80 psi using 50 microm particles of aluminum oxide for 30 seconds, followed by rinsing and drying. Delton FS+ (Dentsply International) and Dyract Flow (Dentsply DeTrey) were applied to the teeth in subgroups following application of: a) an acid etching and bonding agent, b) bonding agent alone or c) air-abrasion alone, respectively. Acid etching (Delton EZ Etch, Dentsply International) and bonding agent application (Prime & Bond NT, Dentsply DeTrey) were done according to the manufacturers' instructions. The teeth were thermocycled for 500 cycles between 5 degrees C and 55 degrees C with dwell time of 15 seconds. Basic fuchsin (0.5%) staining followed by buccolingual sectioning was performed. Microleakage was evaluated at 20x optical magnification. Kruskal-Wallis test was used to make comparisons among six subgroups. Pairwise comparisons were done with the Mann-Whitney U test with the level of significance set as alpha = 0.05. Dyract Flow application as a fissure sealant on air-abraded permanent teeth in combination with acid etching and/or bonding agent provided microleakage results comparable to Delton FS+. Results also showed that the use of air abrasion, alone, resulted in significantly higher microleakage scores.     

Clinical performance and wear resistance of two compomers in posterior occlusal restorations of permanent teeth: six-year follow-up

This study evaluated the clinical performance and wear resistance of compomer restorations placed in the occlusal cavities of posterior permanent teeth after six years. In 1999, 72 Class I restorations were placed by a single operator in 33 patients. Eighty-two percent of these restorations were located in molars. Each patient received at least two restorations, one with F2000 (3M ESPE) and another with Dyract AP (Dentsply). The finished and polished restorations that were free of any failure were considered the baseline. The restorations were clinically evaluated at baseline and at one-, two- and six-year intervals using modified USPHS criteria for color mismatch, marginal discoloration, surface roughness, marginal adaptation, anatomic form and secondary caries. Polyvinylsiloxane impressions (Express, 3M ESPE) were also taken, and models were obtained for indirect wear assessment (Leinfelder scale) at the same intervals. After six years, 11 patients attended the recall. Twenty-seven compomer restorations (11 with Dyract and 16 with F2000) were reevaluated. Data were submitted to the Friedman's test, ANOVA with repetitive measures, Tukey's test (clinical data), Wilcoxon and Kruskal-Wallis tests and the Spearman's correlation test (wear evaluation), all at a significance level of p < 0.05. When comparing the materials, F2000 and Dyract presented similar clinical performance and occlusal wear at the end of the clinical trial. The two compomers showed a significant increase in wear at the six-year follow-up, and a positive correlation (r2 = 0.65) was detected between wear and evaluation time (p < 0.001). Despite the decrease in restoration quality and the increase in occlusal wear, nearly all restorations were considered acceptable after the six-year evaluation.     

Radiopacity of compomers, flowable and conventional resin composites for posterior restorations.

The objective of this study was to densitometrically determine the relative radiopacity (aluminum [Al]-equivalent values) of dentin, enamel, and 20 resin composite materials currently used for posterior restorations. Specimens 5 mm in diameter and 2 mm thick were fabricated from 20 materials (n = 7) for a total of 140 specimens. Human molars were longitudinally sectioned 2.0 mm thick to include both enamel and dentin. The optical densities of enamel, dentin, restorative materials, lead, and aluminum step wedge were obtained from radiographic images, using a transmission photodensitometer. The Al equivalent (mm) for each material was calculated from the linear regression equation of the log of normalized optical density and Al mm thickness obtained from the step wedge. A linear regression of the logarithm of normalized optical density and Al mm thickness was plotted (r2 = 0.9953), and the relative radiopacities, expressed as equivalent thickness of Al, were ranked ordinally. All materials tested, with the exception of an unfilled resin adhesive, complied with ISO Standard 4049, being at least as radiopaque as a 2.0 mm thickness of 99.6% pure Al. Four of six flowable composites had radiopacity values that fell between that of dentin and enamel, while two materials were more radiopaque than enamel. The three compomers tested had radiopacities greater than enamel. In addition, all traditional light- and chemical-cure resin composite materials tested were more radiopaque than enamel. All materials tested, with the exception of one adhesive resin, were at least as radiopaque as dentin and complied with ISO Standard 4049. Clinicians should be able to distinguish these restorative materials radiographically from recurrent decay, voids, gaps, or other defects that lead to clinical failure. Utilization of materials ranked more radiopaque than enamel would enable clinicians to distinguish the restorative material from tooth structure.     

One-year evaluation of two hybrid composites placed in a randomized-controlled clinical trial

Objective

The aim of this prospective randomized-controlled clinical trial is to assess the long-term performance of two direct composite resins in posterior teeth. This study provides a survey of the one-year results.

Materials and methods

A total of 1805 restorations were placed by students in stress-bearing Class I/II cavities (including cuspal-coverage) in molars and premolars in 456 patients. Clinical evaluation was performed at baseline and after one year using modified USPHS criteria. The restorations in each patient were performed either with Ceram X/Prime&Bond NT or Tetric Ceram/Optibond Solo Plus.

Results

After one year 528 fillings with Ceram X and 580 with Tetric Ceram were available for evaluation of substance loss, contact point, color match, marginal staining, marginal adaptation, secondary caries and radiographic examination (if necessary). This represents a recall rate of 61.18% (279 patients). The failure rate per material was 5.3% in the Ceram X group and 6.1% in the Tetric Ceram group. Most of the failures were associated with marginal adaptation/integrity of the filling. A significant influence on the occurrence of a failure was observed for the number of treated teeth per patient, the age of the patient, the mesio-distal extension of the restoration and the tooth position. Gender, material, a previous root canal treatment, the bucco-lingual extension of the filling or cuspal-coverage did not significantly influence the failure rate. Patients attending the first recall were significantly older and had more fillings than patients not attending.

Conclusions

In a group of Class I/II restorations (including cuspal-coverage), there was no significant difference in failure rates between ormocer-based and bis-GMA-based restorative systems after one year. A previous root canal treatment had no negative influence on the failure rate. A longer observation period is indicated to get clear evidence of the long-term performance of these composite resin systems.     

One-year clinical evaluation of two resin composites, two polymerization methods, and a resin-modified glass ionomer in non-carious cervical lesions

AIM: The aim of this study was to examine clinically relevant data on four restorative procedures for non-carious cervical lesions using United States Public Health Service (USPHS)-compatible clinical and photographic criteria and to compare different methods of analyzing clinical data. METHODS AND MATERIALS: Fourteen patients with at least one or two pairs of non-carious lesions under occlusion and a mean age of 50 were enrolled in this study. A total of 56 restorations (14 with each material) were placed by three experienced, calibrated dental practitioners. Two other experienced and calibrated practitioners, under single-blind conditions, followed up on all restorations for a period of one year. Three materials were randomly placed: a micro-hybrid composite with two polymerization methods (G1 and G2), a flowable micro-hydrid composite (G3), and a resin-modified glass ionomer (G4). Statistical analysis was performed using the Kruskall-Wallis test (p<0.05) and a Mann-Whitney U modified test with a corrected significance level. RESULTS: At the one year evaluation time, there were no restorations with secondary caries and the retention rates in G1 (IntenS with a hard polymerization), G2 (IntenS with a soft polymerization), G3 (Filtek flow), and G4 (Fuji II LC) were 85.7% (two losses), 92.8% (one loss), 100%, and 100%, respectively. The total visual comparison of the results at baseline (15 days later) showed significant differences only with the clinical acceptance criterion: G1 was different from G2, with a soft polymerization device (p<0.05). In terms of surface quality at one year, G1, G2, and G3 exhibited a statistically significant difference from G4, p<0.05. The digital analysis at baseline showed significant differences only with the clinical acceptance criterion: G1=G2 was different from G3=G4, p<0.05. At one year, only the microporosity criterion showed any statistical differences: G1=G2=G3 was different from G4, p<0.05. CONCLUSIONS: The resin-modified glass ionomer was easier to use and had a high retention rate, but it failed in terms of surface quality (visual mode) and porosity (digital mode) criteria compared to the others groups. Overall results showed no difference between groups G1 (hard-polymerized) and G2 (soft-polymerized), and only G1 was affected by the marginal edge (p<0.03) and integrity criteria (p<0.02) at one year.     

Clinical evaluation of polyacid-modified resin composite posterior restorations: one-year results.

OBJECTIVE: The aim of this investigation was to evaluate the clinical performance of a new compomer restorative system, Dyract AP, placed in combination with Non-Rinse Conditioner and Prime & Bond NT in permanent posterior teeth. METHOD AND MATERIALS: Fifty Class II and 41 Class I restorations were placed in 39 patients by 1 dentist. The restorations were evaluated directly, with modified US Public Health Service criteria, and indirectly, with color slides and polyvinyl siloxane impressions, at baseline and 6 months and 1 year after placement. Preoperative and 1-year postoperative bitewing radiographs were also taken. RESULTS: All 82 restorations available for 1-year evaluation were in situ. No postoperative sensitivity or pulpal problems were reported. Four Class II restorations (4.9%) failed because of partial fracture or recurrent caries. The percentages of Alfa score for each criterion were color match, 95.1%; marginal discoloration, 57.3%; marginal integrity, 35.4%; anatomic form, 98.8%; and surface texture, 91.5%. The average wear rate of Dyract AP was low (18.5 +/- 11.7 microns at 6 months and 35.7 +/- 13.6 microns at 12 months). CONCLUSION: The excellent handling characteristics, the good clinical performance, and the improved wear resistance suggest that this compomer will provide reliable direct tooth-colored restorations in stress-bearing areas.     

Clinical evaluation of a polyacid-modified resin composite under different conditioning methods in primary teeth

This study evaluated the clinical performance of a polyacid-modified resin composite, Dyract AP (De Trey/Dentsply), under different conditioning methods in primary teeth. Eighty-one box-shaped cavity preparations (three restorations per patient) on the mesial or distal surfaces of primary first or second molars were prepared in 27 patients. The cavity preparations were either non pre-treated or pre-treated with 36% phosphoric acid or NRC (De Trey/Dentsply). The teeth were restored with Prime & Bond NT (De Trey/Dentsply) and Dyract AP. The restorations were evaluated at baseline and 6, 12 and 18-month recalls according to the modified Ryge criteria by two calibrated operators. The data obtained from the clinical assessment of all restorations were subjected to statistical analysis by chi-square-tests at a 0.05 level of significance. The ratings of each criteria were compared among each evaluation period between treatment groups. Statistical analysis revealed no significant difference among each evaluation period between groups in regard to color match, marginal discoloration, marginal adaptation, secondary caries, surface texture, anatomic form and retention.     

Two-year clinical evaluation of four polyacid-modified resin composites and a resin-modified glass-ionomer cement in Class V lesions.

OBJECTIVE: The aim of the study was to compare the clinical performances of four polyacid-modified resin composites (F2000, Dyract AP, Compoglass F, and Elan) and one resin-modified glass-ionomer cement (Vitremer) in Class V abrasion/erosion lesions. METHOD AND MATERIALS: Twenty restorations of each of the five restorative materials were placed in noncarious cervical abrasion/erosion lesions by one dentist. No cavity preparation was attempted. All teeth were isolated with cotton rolls and gingival retraction cord. The materials were manipulated according to the manufacturer's instructions and placed with the help of cervical matrixes. Restorations were finished and polished immediately after the placement. Evaluations were performed at baseline and 6 months, 1 year, and 2 years after placement for retention, color match, cavo-surface marginal discoloration, anatomic form, marginal adaptation, secondary caries, and postoperative sensitivity. RESULTS: Retention levels at 2 years were 90% for F2000, 90% for Dyract AP, 89% for Compoglass F, 84% for Elan, and 95% for the Vitremer restorations. No statistically significant differences were found among the materials after 2 years for any evaluation category. CONCLUSION: Polyacid-modified resin composite and resin-modified glass-ionomer cement restorations showed acceptable clinical performance after 2 years.     

One-year clinical performance of a self-etching adhesive in class V resin composites cured by two methods

This study evaluated the clinical performance of a self-etching adhesive for resin composites over one year. Thirty pairs of restorations of Pertac II, using the adhesive Prompt L-Pop, were placed in caries-free cervical erosion/abfraction lesions without tooth preparation. One of each pair was cured using "soft-start" polymerization, while the other was polymerized with high-intensity halogen light. Restorations were clinically evaluated at baseline, six and 12 months using modified Ryge/USPHS criteria. Although no significant difference (p>0.05) was observed between the curing methods, adhesive performance was poor, with a 35% loss of restorations overall.     

Six-year clinical evaluation of polyacid-modified composite resin used as fissure sealant

The aim of this study was to evaluate retention and efficacy of polyacid-modified composite resin used as fissure sealant (Variglass V.L.C.) after six years. Three-hundred and seventy permanent first molars were sealed. After six years, 42.0% of the original group was re-examined and the sealant was found to be totally present in 3.4%, partially present in 16.2% and absent in 70.4% of the previously sealed occlusal surfaces. During the 6 years period, 9.5% of the sealed surfaces became carious, 25.0% were filled and 65.5% remained sound. Although the retention rate of the material has been very low, it appears to have prevented dental caries in 2/3 of the teeth evaluated after six years of placement.     

One-year clinical evaluation of an anterior composite resin.

An anterior composite resin was evaluated in a clinical study of 93 Class III and Class IV restorations placed in patients aged 12 to 50 years. The restorations were evaluated at baseline, 6 months, and 1 year. Sixty-four (79%) of the 81 restorations examined at the 1-year recall were unchanged. Marginal discoloration and changes in surface appearance and marginal adaptation accounted for most of the changes. All changes appeared in patients younger than 14 years, which may indicate that the patients had problems in oral hygiene. Replicas of randomly selected restorations showed smooth surfaces and well-sealed margins with a smooth transition from restoration to enamel. Some restorations showed marginal breakdown and a pitted irregular surface.     

Changes in properties of polyacid-modified composite resins (compomers) following storage in acidic solutions

The interaction of three polyacid-modified composite resins (compomers) with various acidic storage solutions, and also water, over periods of time up to 6 months has been studied and compared with those of a glass-ionomer and a composite resin. This interaction has been shown to vary in a complex way with length of storage and nature of the acid, and citric acid was found to be the most aggressive storage medium for glass-ionomer cement, and also for the compomers. The pure composite resin, by contrast, was relatively unaffected by all of the acid solutions examined. In all acids, the compomers showed a distinct buffering effect, i.e. they increased the pH towards neutral, as did the glass-ionomer. The extent of this also varied with duration of storage and nature of the acid. The biaxial flexure strength was determined and found to be essentially unaffected by the complex chemical interactions with acidic storage solutions. Values obtained for the compomers were lower than those of the composite resin, but above those of the glass-ionomer. Fourier-transform infrared (FT-IR) spectroscopy was employed to study the changes in the compomers following storage in the aqueous media, but bands were broad and no detailed assignments could be made. There were changes in the region of the spectra associated with metal carboxylates however, and this indicates that the secondary acid-base reaction had occurred following water uptake.     

Three-year clinical evaluation of a polyacid-modified resin composite in minimally invasive occlusal cavities

OBJECTIVE: The aim of this study was to evaluate the 3-year clinical performance of one polyacid-modified resin composite material (PMRC). Dyract, in minimally invasive occlusal cavities and its neighbouring fissures. METHODS: One hundred and sixteen restorations of the material investigated were placed by a single operator in a group of selected children under controlled conditions. Isolation of the restorations was accomplished with the use of cotton rolls and aspiration. Using modified US Public Health Service (USPHS) codes and criteria, the restorations were reviewed clinically within 1 week of placement (baseline), and thereafter at 6 months, 1, 2 and 3 years. RESULTS: After 3 years, marginal discolouration was present in 8.6% of the restorations. The marginal adaptation was rated as partly sealed (Oscar-Alpha) in 107 (92.2) of the restorations. Five restorations had lost their sealant components, while four restorations were partly sealed with explorer-catch after 3 years. Although wear of the restorations was considerable, restorations rated as 'partly sealed' had at least two-thirds of their sealant components fully retained. Recurrent caries was associated with four (3.4%) restorations. CONCLUSION: In this clinical study, the retention rate of the tested PMRC material was good, although a marked occlusal wear was evident. The marginal adaptation of the PMRC at the enamel site would probably have been better by the use of enamel-etching. Provided the marginal adaptation and wear resistance of the material is further improved, clinical use of PMRCs in minimally invasive occlusal cavities can be advocated.     

Bond strength and interfacial micromorphology of compomers in primary and permanent teeth

Objectives. To (1) test and compare the shear bond strength of compomers (Compoglass, Dyract, Hytac) to primary and permanent dentin, (2) compare the values to those obtained with a resin-modified glass ionomer (Vitremer), and (3) evaluate the material–dentin interfacial morphology.
Sample and methods. The facial and lingual surfaces of 32 primary and 32 permanent teeth were used. The manufacturers' instructions were followed for the bonding procedures. After bonding, the teeth were thermocycled and sheared.
Results . ANOVA and Student-Newman-Keuls test revealed that the shear bond strength for Dyract was significantly higher than for the other restorative systems tested, both for primary ( P <0·001) and permanent ( P <0·01) teeth. Compoglass bond strength was significantly lower than Vitremer for the primary teeth dentin ( P <0·01). The shear bond strength for Compoglass to permanent dentin was significantly lower than for all other restorative systems ( P <0·001). There was a significantly higher shear bond strength for Compoglass ( P <0·05) and Dyract ( P <0·01) restorative systems for prim-ary compared to permanent teeth. For all products tested, all samples revealed cohesive failures. The highest frequency of cohesive failure was reported with Compoglass in both primary and permanent teeth and for Hytac and Vitremer in permanent teeth. Micromorphologically, all restorative systems revealed good adaptation to the underlying dentin; however, there was no evidence of the formation of a hybrid layer or deep resin penetration inside the dentinal tubules. There was no difference in the interfacial morphological adaptation between the primary and permanent teeth.
Conclusions . The compomers tested had shear bond strength values between those of resin-modified glass ionomers and resin composites.