Biomedical subjects

Valeria V Gordan

Publications and source records attributed to Valeria V Gordan.

18 recordsLinked to original sources

PubMed2006

Two-year clinical evaluation of repair versus replacement of composite restorations.

PURPOSE: To investigate the effectiveness of alternative treatments to the replacement of resin-based composite (RBC) restorations through a prospective longitudinal cohort clinical study. MATERIALS AND METHODS: Forty patients aged 27 to 77 years (mean=55) with 88 RBC restorations, with one or more features that deviated from ideal, participated in the study. They were assigned to five treatment groups: repair (N=25), sealing of defective margins (N=13), resurfacing (N=18), replacement (N=16), and the no-treatment group (N=16). The replacement and no-treatment groups served as comparison groups and received random assignment. Two clinicians examined the quality of the restorations (N=88) prior to the assigned treatment, and at subsequent recalls (1 and 2 years) using a modified Ryge criteria (Alfa, Bravo, and Charlie, meaning clinically excellent, clinically acceptable with one or more features that deviated from ideal, and clinically unacceptable, respectively) that observed (1) color, (2) marginal adaptation, (3) anatomic form, (4) surface roughness, (5) marginal staining, (6) bulk discoloration, (7) contact, (8) secondary caries, (9) postoperative sensitivity, and (10) luster. RESULTS: At 1- and 2-year recalls, 66 (75%) and 58 (66%) restorations were examined. Kruskal-Wallis Test showed significant differences for marginal adaptation and marginal staining for both 1- and 2-year recall exams (p < .05). The repair, sealant, and replacement groups presented significant improvement when compared with the no-treatment group for marginal adaptation. The repair and replacement groups showed superior results when compared with the no-treatment group for marginal staining. CONCLUSION: RBC restorations that present less-than-ideal marginal adaptation and stained margins are better off being repaired. CLINICAL SIGNIFICANCE: Repair of resin-based composite (RBC) restorations is a conservative option for treatment of RBC restorations with inadequate marginal adaptation and marginal staining.

Adult↗

PubMed2006

Two-centre evaluation of a resin composite/ self-etching restorative system: three-year findings.

PURPOSE: This two-centre study evaluated the clinical performance of Class I and Class II restorations of the giomer material Beautifil, placed using Fluorobond, a self-etching adhesive system, to determine the suitability of the test system as an alternative for the restoration of posterior teeth. MATERIALS AND METHODS: A total of 108 restorations, comprising 72 Class II and 36 Class I restorations, was placed predominantly in molars (82%). Evaulations using modified USPHS/Ryge criteria were conducted at baseline and thereafter at 6 months and 1, 2, and 3 years. Die stone replicas of the restored teeth were examined retrospectively. RESULTS: A total of 5 restorations was found to fail during the study-- 3 in the first year and 2 during the third year of the study. Occlusal marginal adaptation was less than ideal at baseline in 11% of cases, primarily as a consequence of overcontouring, as observed in the die stone replicas. The combined percentage Alpha ratings at 3 years were: colour match, 98%; marginal adaptation (occlusal), 78%; marginal adaptation (proximal), 97%; anatomic form (occlusal), 99%; anatomic form (proximal), 95%; surface roughness (occlusal), 100%; surface roughness (proximal), 100%; marginal staining (occlusal), 90%; marginal staining (proximal) 81%; interfacial staining (occlusal), 99%; interfacial staining (proximal), 100%; contacts (occlusal), 95%; contacts (proximal), 93%; sensitivity, 100%; secondary caries, 100%; lustre of restoration, 100%. CONCLUSION: It is concluded that the 3-year performance of Fluorobond-bonded Beautifil for Class I and II restorations demonstrated some marginal changes, but most of the direct evaluation ratings were > 90% Alpha, with the performance observed being similar in the two centres.

Adult↗

PubMed2005

Research in general dental practice.

Spurred by an initiative by the National Institute of Dental and Craniofacial Research in the USA, this article presents the need for a change in clinical dental research towards practice-based research. It outlines the shortcomings of past and present-day research in dentistry, with emphasis on the lack of clinical relevance of much of the research performed. The slow transfer of sound research findings to clinical practice is also a major problem. The article reviews some problems related to restorative dentistry and how they have adversely affected general dental practice. Practice-based research places emphasis on the problems experienced by clinicians in the routine care of patients. Clinicians should be linked together in research networks. The problems they face in dental practice and the clinical experience they have will form the basis for studies by the network. Experienced clinical researchers will provide guidance and statistical support for the studies initiated by the clinicians.

Dental Care↗

PubMed2005

Four-year clinical evaluation of a self-etching primer and resin-based restorative material.

PURPOSE: To evaluate the performance of a universal resin-based restorative material (Beautifil) in combination with a self-etching primer (Fluorobond) for posterior restorations. METHODS: 61 restorations, 26 Class I and 35 Class II, were placed by two clinicians in 31 patients under rubber dam isolation. Two other calibrated clinicians evaluated the restorations using USPHS/Ryge criteria observing the following characteristics: color match, marginal adaptation, anatomy, roughness, marginal staining, interfacial staining, contact, secondary caries, and luster. Chi-Square and Fisher's Exact Test were used for statistical analysis (alpha=0.05). RESULTS: All the restorations were assessed at baseline and alpha scores predominated for all criteria. All restorations were examined at the 1-year recall examination. 58 restorations were examined at the 2-year recall (23 Class I and 35 Class II), 47 (16 Class I and 31 Class II) at the 3-year recall. The present 4-year report covers 39 restorations (12 Class I and 27 Class II). Marginal adaptation, staining, anatomy, and color matching constitute the majority of the recorded changes. Chi-Square and Fisher's Exact Test of the frequency of clinical rating of each characteristic showed that there were no statistically significant differences at each recall with respect to the baseline observations (P> 0.05), except for occlusal marginal stain. Statistical significance was detected for the occlusal marginal stain at 1-year (P= 0.06), 2-year (P= 0.01) and 4-year (P= 0.002) when compared to baseline data.

Adult↗

PubMed2004

The effect of mechanical undercuts on the strength of composite repair.

BACKGROUND: The authors conducted an in vitro study to test the hypothesis that undercuts prepared in old composite restorations could improve the strength between the restoration and a flowable composite as repair material. METHODS: The authors used three composites to fabricate cylinders as repair substrates. The etched-only group was ground, etched, dried and built up with a flowable composite. For the undercut group, the authors introduced arrays of fissures on the surfaces before preparing the specimens for subsequent buildup in the manner described for the etched-only group. They made nonrepaired cylinders for baseline measures of strength. They sliced all finished cylinders into slender bars with a diamond saw. Flexure strength values were determined by a three-point-bending test. RESULTS: Nonrepaired bars exhibited statistically significantly higher flexure strength values than did repaired bars, as determined by Wilcoxon rank sum test. Two-way general linear model showed that both material (P < .0001) and undercut (P = .0207) exhibited a statistically significant influence on the repaired flexure strength. Repair substrate with elastic modulus close to that of repair material exhibited a greater percentage of recovery of the respective cohesive strength. Compared with the etched-only group, the undercut group yielded a higher mean flexure strength with one composite but a lower mean flexure strength with the other two. Examination of the fractured surfaces showed that a significant number of undercuts were filled only partially. CONCLUSION: Flexure strengths of repaired specimens always were lower than the cohesive flexure strengths of the materials being repaired. Undercuts did not generally improve repair strength. CLINICAL IMPLICATIONS: Small undercuts on the surface of composite often are difficult to fill completely, resulting in areas of stress concentration that result in no improvement in the repair strength.

Analysis of Variance↗

PubMed2004

The effect of surface finishing and storage solutions on the color stability of resin-based composites.

BACKGROUND: The authors tested the hypothesis that surface-finishing treatments and the type of storage solutions significantly affected the staining of resin-based composites, or RBCs, and unfilled resins, or URs. METHODS: Fifty-four RBC and 54 UR disks were polymerized through a polyester film strip (Mylar, DuPont, Wilmington, Del.) and polished in one of three groups: 1-micrometer aluminum oxide, 15-microm diamond plate and no treatment (polyester film). All specimens were immersed in water for two days and then in coffee, cola or red wine for seven more days at 37 C. The authors recorded tristimulus color measurements before the immersions; after one and two days in water; and after one, two, three and seven days in the storage solutions. RESULTS: Most of the color changes occurred between day 2 in water and day 7 in the staining solution. Analysis of variance showed that the finishing treatment and storage solution significantly influenced the overall color change (deltaE), and interactions occurred between the finishing treatment and the storage solution (P < .0001) for both materials. RBC specimens generally exhibited greater color changes than did UR specimens. The polyester film finishing exhibited the greatest amount of color change, while the diamond finishing exhibited the least amount of color change. Immersion in wine caused the greatest color change for both materials; cola and coffee resulted in the smallest color change for RBC and UR specimens, respectively. CONCLUSIONS: Finishing treatments and storage solutions significantly affect the surface staining of RBC materials. Polyester film finishing and red wine produced the greatest color change after seven days for RBC specimens. CLINICAL IMPLICATIONS: Clinicians should remove the polyester film-finished surface and advise patients that drinking wine could intensify surface staining on RBC restorations.

Aluminum Oxide↗

PubMed2004

Esthetic dentistry in North American dental schools.

OBJECTIVES: Esthetic dentistry is among the most dynamic areas of contemporary clinical dentistry. Teaching programs in dental schools have a strong effect on the practice of dentistry, not only for recent graduates, but also for established clinicians, especially with respect to new techniques and concepts. The purpose of the study reported here was to assess the frequency and extent of the teaching of esthetic dentistry in North American dental schools and to report how it differs among the various schools. MATERIALS AND METHODS: A 19-question survey was mailed to 64 North American dental schools. The questions inquired about the priority given to the teaching of esthetic dentistry in the school; how the subject was taught (through regular curricular courses; through a multidisciplinary approach or through elective classes); the duration of the esthetic dentistry course; the nature of the course content (theoretical or practical); the esthetic procedures taught to undergraduate students; the level of interaction among different disciplines in the teaching of esthetic dentistry; and the techniques and commercial materials used. The responses were summarized as percentages based on the number of schools that responded to each question. RESULTS: Fifty-two (81%) of the 64 dental schools completed and returned the questionnaire. Twenty-five of these schools (48%; designated group A) reported having a course exclusively for the teaching of esthetic dentistry. Twenty-seven schools (52%; designated group B) reported that esthetic dentistry was addressed in multiple courses, i.e., no specific course was available. Four schools in group B (15%) were in the process of developing a separate course for esthetic dentistry. In group A schools, esthetic dentistry was taught mainly in the operative dentistry department or division. The most frequent course duration was 4 to 6 months, but there were marked variations. Thirteen (52%) of these 25 schools had didactic and practical teaching at both the preclinical and the clinical levels. The schools in group B reported that only clinical instruction in esthetic dentistry was provided. Several concerns were addressed in the courses offered in group A schools: extrinsic and intrinsic discoloration, bleaching, diastemas, malformation and malpositioning (the latter including rotation, intrusion and labio-linguoversion), and replacement of amalgam and gold restorations. Only 7 (28%) of the group A schools reported having the support of an inhouse laboratory. The esthetic procedures taught were similar for schools in group A and group B. The use of direct posterior composite restorations, all-ceramic crowns and nonvital bleaching was more common among group B schools. Ceramic inlays, onlays and indirect posterior composite restorations were not taught by 4 (16%) of the schools in group A and 7 (26%) of the schools in group B. CONCLUSIONS: The teaching of esthetic dentistry in North American dental schools is highly variable and in many schools is shared among different disciplines. Dental schools should work together to establish the parameters for teaching this subject and should formulate the necessary standards for education and research in this new field.

Canada↗

PubMed2004

Evaluation of etching time on dentin bond strength using single bottle bonding systems.

PURPOSE: Incomplete infiltration of the demineralized collagen network may result in a weak zone within the hybrid layer and between the hybrid layer and dentin. The current study evaluates whether reducing the etching time to 5 s from the recommended 15 s or increasing it to 30 s has an effect on dentin bonding. MATERIALS AND METHODS: 108 extracted molars were assigned to 3 bonding agent groups (n = 36): (a) Single Bond (SB), (b) One-Step (OS), and (c) Syntac Single Component (SSC). Each group was further divided into three subgroups (n = 12) of different etching times: 5, 15, and 30 s. All groups were bonded with Z100 composite resin according to the manufacturer's instructions. All specimens were thermocycled 300 times between +/-5 degrees C and +/-55 degrees C, and shear bond strength testing and mode of failure analysis were performed. RESULTS: The bond strength of SB (5 s: 15.5 MPa +/- 4.4; 15 s: 16.5 MPa +/- 3.1; 30 s: 16.8 MPa +/- 3.2) and OS (5 s: 13.7 MPa +/- 1.8; 15 s: 12.4 MPa +/- 3.8; 30 s: 10.6 MPa +/- 3.8) showed no significant differences (p < 0.05) for the different etching times. For SSC, different etching times showed significant differences (5 s: 10.9 MPa +/- 1.8; 15 s: 7.5 MPa +/- 2.5; 30 s: 6.4 MPa +/- 2.1). The mode of failure for SB and OS was adhesive or mixed adhesive/cohesive. For SSC, all failures were adhesive. CONCLUSION: Etching times of less than 15 s do not seem to adversely affect bonding to dentin.

Acid Etching, Dental↗

PubMed2003

Teaching students the repair of resin-based composite restorations: a survey of North American dental schools.

BACKGROUND: The purpose of this study was to evaluate whether North American dental schools teach students to repair resin-based composite, or RBC, restorations and to compare the findings with those from similar European surveys. MATERIALS AND METHODS: The authors mailed a 15-item questionnaire to 64 dental schools in the United States, Canada and Puerto Rico. The survey asked whether the school taught repair of RBC restorations and inquired about the respondent's experience with such procedures. Questions also elicited reasons why schools taught or did not teach repair, information in regard to relevant decision-making processes, criteria for deciding whether to perform repairs and the nature of the instruction (theoretical, practical, preclinical or clinical). RESULTS: Fifty-two (81 percent) of 64 schools participated in the survey. Thirty-seven (71 percent) of the respondents reported that they taught undergraduate students repair techniques as an alternative to replacing failing RBC restorations. Twenty-seven (73 percent) of these 37 schools reported that such teaching was at the clinical level, while only three schools (8 percent) reported that it was included in formal lectures as part of preclinical courses. The major reasons given for teaching students how to repair RBC restorations were tooth structure preservation and reduction of potentially harmful effects on the pulp. Indications included the correction of marginal defect and marginal discoloration. CONCLUSIONS: More than one-half of the respondents reported that they taught repair of RBC restorations and that patients were willing to accept such treatment. Most schools considered the repair of RBC restorations to be a definitive measure and reported that, on average, expected a repaired RBC restoration to have a longevity of four years.

Canada↗

PubMed2002

Comparison of the apical seal obtained by a dual-cure resin based cement or an epoxy resin sealer with or without the use of an acidic primer.

This study compared the apical leakage of roots obturated with gutta-percha using either a dual-cure resin based cement (Panavia F) or an epoxy-resin sealer (Thermaseal plus) with or without the application of an acidic primer (ED Primer). Eighty-six single rooted canine teeth were decoronated, cleaned, and shaped by using hand and rotary instruments, randomly divided into four groups, and obturated as follows: group A (n = 20): ED Primer applied followed by thermoplastized obturation with gutta-percha and Thermaseal Plus sealer; group B (n = 20): thermoplastized obturation with gutta-percha and Thermaseal Plus; group C (n = 20): ED primer applied followed by thermoplastized obturation with gutta-percha and Panavia F; group D (n = 20): thermoplastized obturation with gutta-percha and Panavia F. Both a negative control (n = 3; entire root coated with wax) and a positive control (n = 3; obturated with only a fitted master cone) were included in the study. Groups A, B, C, D, and the controls were immersed in molten sticky wax, leaving the apical 2-mm exposed, and quickly chilled. All teeth were immersed in 1% methylene blue dye solution for 10 days, rinsed, and sectioned longitudinally. Apical dye penetration was measured stereomicroscopically at 10-fold magnification. The analysis of variance and Duncan Multiple Range were used for result analysis. The specimens obturated with gutta-percha and an epoxy-resin sealer (with or without an acidic primer) demonstrated significantly less linear dye penetration than specimens obturated with gutta-percha and the dual-cure, resin-based cement (with or without an acidic primer).

Analysis of Variance↗

PubMed2002

Self-etching primer and resin-based restorative material: two-year clinical evaluation.

PURPOSE: This study was undertaken to evaluate the performance of posterior restorations placed using a self-etching primer (Fluorobond, Shofu Inc., Kyoto, Japan) and a universal resin-based restorative material (Beautifil, Shofu Inc., Kyoto, Japan). MATERIALS AND METHODS: The 61 restorations evaluated were 26 Class I and 35 Class II that were placed by two clinicians in 31 patients. Two other calibrated clinicians evaluated the restorations using United States Public Health Service (USPHS)/Ryge criteria observing the following characteristics: color match, marginal adaptation, anatomy, roughness, marginal staining, interfacial staining, contact, secondary caries, and luster. Restorations were placed under rubber dam isolation. Chi-squared and Fisher's exact tests were used for statistical analysis (p = .05). RESULTS: All the restorations were assessed at baseline and alfa scores predominated for all criteria. At the 12-month recall examination, one patient dropped out of the study and two restorations were replaced by a clinician not involved in the project. At 24-month recall, 58 restorations were examined (23 Class I and 35 Class II). From baseline to 24 months, 19 of the 44 restorations changed from alfa to bravo and 13 from bravo to alfa for a variety of reasons. No significant differences were found for any of the clinical criteria (p > .05). The 2-year recall substantiated the 1-year results. CONCLUSION: Beautifil and the self-etching primer Fluorobond provided satisfactory restorations after a 2-year observation period. CLINICAL SIGNIFICANCE: Beautifil restorative material and Fluorobond bonding system provided satisfactory results when placed in Class I and Class II preparations for a period of 2 years.

Acid Etching, Dental↗

PubMed2002

Replacement of resin-based composite: evaluation of cavity design, cavity depth, and shade matching.

OBJECTIVE: The aim of this study was to evaluate the effect of different cavity designs, cavity depths, and shade matching on the dimensions of Class I resin-based composite preparations during replacement of the restoration. METHOD AND MATERIALS: Forty Class I cavity preparations were prepared in extracted premolars. The occlusal depths varied from 1.5 to 2.5 mm. In 20 teeth, the buccal and lingual walls were perpendicular to the pulpal floor; in another 20, they were divergent to the pulpal floor. Impressions were made of all preparations. The cavities were restored with resin-based composite. All subgroups were further divided into another two subgroups (n = 5), in which half of the teeth were restored with shade that matched the tooth and the other half were restored with a resin composite that was three shades different from the tooth. After 168 hours in distilled water, the restorations were removed. New impressions were made, and a total of 80 stone casts were fabricated. The perimeter and area of the restorations were recorded with a video-based imaging system. The dimensions of the postoperative cavity preparations were compared to the initial cavity sizes. RESULTS: The depth of the original cavity preparation had a statistically significant effect on the change in cavity dimension, as measured by area and perimeter. The 2.5-mm-deep cavities showed greater loss of tooth structure. No statistically significant difference was found for different cavity designs or shade matching. CONCLUSION: Replacement of Class I resin-based composite restorations results in loss of tooth structure. The deeper the original cavity preparation, the greater the loss of tooth structure at the occlusal cavosurface margin during replacement.

Analysis of Variance↗

PubMedDate not supplied

2-year clinical evaluation of alternative treatments to replacement of defective amalgam restorations.

OBJECTIVE: To investigate the effectiveness of alternative treatments for replacing defective amalgam restorations through a prospective longitudinal cohort clinical study. METHODS: Forty-five patients aged 21 through 77 (mean=56) years with 113 defective amalgam restorations, which were independently diagnosed during treatment planning, participated in the study. These patients were assigned to 5 treatment groups: repair (n=20), sealing of defective margins (n=23), refurbishing (n=23), replacement (n=23) and no-treatment (n=24). The replacement and no-treatment groups served as comparison groups and received random assignment. Two clinicians examined the restorations (n=113) prior to and after the assigned treatment and at subsequent recalls, using a modified Ryge Criteria that included marginal adaptation, anatomy, contact, post-operative sensitivity and secondary caries. RESULTS: At 1- and 2-year recalls, 79 (70%) and 74 (65%) restorations were examined. Kruskal-Wallis Test showed significant differences for marginal adaptation and anatomic form for both 1- and 2- year recall exams (p<.05). The repair and replacement groups had significant differences when compared to the no-treatment group. CONCLUSIONS: Defective restorations that have a Bravo rating for clinical characteristics other than marginal integrity and anatomical form do not need to be immediately replaced.

Adult↗

PubMedDate not supplied

Short- and long-term clinical evaluation of post-operative sensitivity of a new resin-based restorative material and self-etching primer.

This study evaluated the post-operative sensitivity of posterior restorations restored with a resin-based restorative material and a self-etching primer. Forty-six restorations, 28 Class I and 18 Class II were placed by two clinicians in 25 patients. After cavity preparations were completed under rubber dam isolation, they were restored using a self-etching primer (Fluorobond, Shofu Inc, Kyoto, Japan) and a resin-based restorative material (Beautifil, Shofu Inc, Kyoto, Japan). Patients were contacted on days 2 and 7 post-operatively and questioned regarding the presence of sensitivity, the stimuli that created sensitivity, the length of time the sensitivity lasted and its intensity using a rating scale from slight to severe. If sensitivity was experienced on day 7, patients were also contacted on days 14, 30 and 90 to assess the degree of sensitivity. All patients were recalled after 6-, 12- and 24-months for further evaluation of any sensitivity experienced. Chi-Square and Fisher's Exact Test were used for statistical analysis. At day 2, six restorations were sensitive to cold with no statistical difference (p > 0.05) from the restorations that were not sensitive. At day 7, only two restorations were sensitive. No sensitivity was present after day 14, which was also confirmed at the six-month recall. No correlation could be established among the duration of the sensitivity, the degree of pain and the causes that initiated sensitivity (p > 0.05). At one-year recall, one restoration was replaced due to post-operative sensitivity that started after the six-month recall. No sensitivity was noted at the 24-month recall. No correlation (p > 0.05) was found between sensitive restorations and those with a normal response throughout the study. The study showed that Fluorobond self-etching primer and Beautifil resin-based restorative material, when placed in posterior restorations, do not result in long-term post-operative sensitivity.

Acid Etching, Dental↗

PubMedDate not supplied

Effect of surface finishing and storage media on bi-axial flexure strength and microhardness of resin-based composite.

This in vitro study tested the following null hypotheses: (1) surface finishing treatments do not significantly affect the biaxial flexure strength and microhardness of resin-based composites (RBC) and (2) storage media do not significantly affect these physical properties. Discs (81 RBC and 81 UR; 3M/ESPE) were prepared using a circular polyethylene mold (2.4-mm thick x 16.7 mm in diameter) that was polymerized through a Mylar strip and divided into three surface finishing treatment groups: 1 microm aluminum oxide slurry; 15 microm diamond and a Mylar strip. Randomly selected controls for each finishing group were stored at room temperature in individual vials. Test specimens were immersed in water, stored at 37 degrees C for two days and transferred for an additional seven days to one of three aqueous storage media at 37 degrees C: coffee (pH 5.1), cola (pH 2.4) or red wine (pH 3.7). Post immersion (nine days total), the specimens were tested for biaxial flexure strength (BFS) and Vicker's microhardness (VHN). ANOVA and Tukey's HSD test were used for statistical analysis. ANOVA results indicated that surface finishing treatments had a significant effect on the biaxial flexure strength and microhardness of the RBC and the UR specimens. BFS results for RBC specimens were AL>DD>ML (p<0.0001) and VHN results were AL, DD>ML (p<0.0001). Storage in wine medium reduced the VHN of UR specimens significantly. Both alternative hypotheses were accepted. In addition, the Mylar finishing group, because of the resin-rich surface layer, yielded the lowest mean values of BFS and VHN.

Aluminum Oxide↗

PubMedDate not supplied

The effect of variation in etching times on dentin bonding.

Twelve extracted molars were assigned into four groups of three to observe how different etching times affect the depth of dentin demineralization and the thickness and morphology of the hybrid layer. The four groups were subjected to etching times of 5, 15, 30, and 60 seconds. To study the hybrid layer, another 27 molars were assigned into groups of nine; each group was etched using a different single-bottle bonding agent. In addition, each group was divided into three subgroups, with three different etching times of 5, 15, and 30 seconds. Following the bonding procedure, the specimens were bonded using Z100 composite and processed for observation using a scanning electron microscope. There was a direct correlation between etching time and depth of demineralized zone. The hybrid layer thickness correlated directly to the etching time. Increased etching time demineralized the dentin surface to a depth greater than resin monomers could penetrate, producing a thick, poorly infiltrated hybrid layer. Reducing etching time reduces the depth of the demineralized zone and may be effective for achieving complete penetration and for sealing the dentin surface.

Acid Etching, Dental↗

PubMedDate not supplied

Marginal gap repair with flowable resin-based composites.

This study was designed to test the hypothesis that the flowable/dentin interface has the weakest bond and highest frequency of failure when a resin-based composite is repaired using a flowable composite. Comparing three specific groups--dentin, flowable composite, and hybrid composite-under the Kruskal-Wallis test showed that the mean bond strength values at the flowable/dentin interface and within the dentin were significantly lower than those at the hybrid/flowable interface and within the flowable resin. Dentin near the pulp chamber yielded consistently lower bond strength values than dentin located at the dentino-enamel junction. Bonding at the flowable resin/dentin interface showed the weakest bond and highest frequency of failure.

Analysis of Variance↗

PubMedDate not supplied

Alternative treatments for resin-based composite and amalgam restorations with marginal defects: a 12-month clinical trial.

This clinical trial sought to evaluate the effectiveness of alternative treatment for replacing amalgam and resin-based composite restorations with marginal defects. The study recruited 66 patients with 271 restorations. Each restoration was assigned randomly to one of five groups: Sealant, Refurbishing, Repair, Replacement, and Untreated. Two clinicians evaluated the restorations according to USPHS/Ryge criteria at baseline (Kappa 0.74) and one year after the treatment (Kappa 0.81). The scoring of the margins improved (from bravo to alfa) after the experimental treatments. None of the treatments showed significant degradation of the margins during the 12-month observation period.

Adolescent↗