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PubMedDate not supplied

Marginal hybrid layer in Class V restorations.

The aim of this study was to evaluate the morphology of the hybrid layer (identified as marginal hybrid layer) along the cervical margins of Class V restorations using several bonding systems. Class V restorations were prepared in vitro at the CEJ in extracted third molars. Three different bonding systems were selected: Scotchbond 1 (Single Bond), Scotchbond MP, and Clearfil Liner Bond 2V. After finishing each restoration with disks, each margin was polished for one minute with polishing paste. The margins of half of the restorations were then treated with 10% phosphoric acid for five seconds, washed in deionized water, and then stored in water for 24 hours before SEM analysis. The margins of the other half of the restorations were treated with 10% phosphoric acid for five seconds, then with 1.5% NaOCl gel for two minutes to remove noninfiltrated collagen, then washed and stored in water for 24 hours. Each sample was gold coated and observed under SEM. A one-way ANOVA was performed to determine if there were any statistically significant differences in hybrid layer thicknesses. The thickness of the marginal hybrid layer measured under SEM was 1.5-2.5 microns thick in Scotchbond MP and Scotchbond 1 but varied from 0.0 to 12.0 microns in Clearfil Liner Bond 2V when observed after NaOCl postpolishing procedures. Far more porosities were seen in the marginal hybrid layer of Clearfil Liner Bond 2V. Enamel margins were free from a hybrid layer in both groups. This study demonstrated that collagen fibrils are not completely infiltrated by adhesive resin at the CEJ level along the cavorsurface margin of the restorations. The presence of noninfiltrated collagen along the external margins may reduce the sealing capability of bonding systems, leaving many open spaces and gaps, which may jeopardize the durability of the bond over time.

Acid Etching, Dental↗

PubMedDate not supplied

Microleakage of bonded amalgam restorations: effect of thermal cycling.

This study examined the effect of thermal cycling on the microleakage of bonded amalgam restorations. Three dental amalgam alloys and a gallium alloy were tested with two adhesive resin systems and copal varnish as a control. Class V cavity preparations were prepared on 168 freshly extracted premolars or molars. The preparations were placed parallel to and 1.0 mm occlusal to the cementoenamel junction (CEJ). Four groups of 42 teeth each were treated with one of the following adhesive dentin systems: Bond-It, All-Bond 2/Resinomer or a copal varnish (Copalite). The four groups of 42 teeth each were then restored with one of three dental amalgams: Orosphere Plus, Indiloy, Oralloy or a Gallium alloy (Galloy), resulting in 12 test groups of 14 teeth each. The specimens were stored in double distilled water at 37 degrees C for 24 hours. Final contouring and polishing of the restorations were performed under water spray. Half of the restorations in each group were thermocycled for 3000 cycles (5 degrees C-37 degrees C-55 degrees C-37 degrees C) with a dwell time of 15 sec at each temperature. The other half were stored in double distilled water at 37 degrees C for 24 hours. Then all 168 restorations were stained with dye, sectioned and scored for microleakage. Results showed that the adhesive dentin systems reduced microleakage in amalgam restorations compared to copal varnish only in non-thermocycled specimens. Statistical analysis of the results showed that there was an extremely significant difference (p < 0.001) in microleakage between the non-thermocycled and the thermocycled specimens in all test groups, whereas, there was no significant difference (p > 0.05) among thermocycled specimens. The reduction of microleakage was not significantly different between Bond-It and All-Bond 2/Resinomer in non-thermocycled specimens. Oralloy showed the most microleakage in the non-thermocycled groups when compared to the other alloys using the same adhesive liner.

Analysis of Variance↗

PubMedDate not supplied

Cervical compomer restorations: the role of cavity etching in a 48-month clinical evaluation.

Compomers are defined as polyacid-modified resin composites. They are supposed to combine the advantages of traditional glass-ionomer cements with resin composites. This study clinically evaluated a compomer in cervical cavities. Sixty cervical cavities in premolars and molars (24 with cervical caries and 36 with abrasions) randomly divided into two groups of 30 teeth (Group 1 and Group 2) were restored with Dyract (DeTrey-Dentsply, York, PA 17405-0872). The cavities of Group 2 were etched for 30 seconds with orthophosphoric acid before compomer application, while the Group 1 cavities received no treatment. All the restorations were evaluated every six months, up to 48 months: characteristics assessed according to USPHS-modified standards were retention, secondary caries, post-operative sensitivity, marginal adaptation and discoloration, color and wear. The Kaplan-Meier's survival analysis was performed. In both groups, retention was high without any statistically significant difference. No difference was found between the two groups for caries, post-operative sensitivity and wear--that all had a low incidence. Color was not perfectly matched, however, there was no statistically significant difference between the two groups. Marginal discoloration and marginal adaptation loss were significantly higher in non-etched group (p < 0.05). Clinically relevant failure required 17.2% of restorations in the non-etched group and 10% in the etched group to be replaced: this difference was not statistically significant. Dyract has an acceptable clinical behavior when used in cervical cavities. Its marginal adaptation is enhanced by etching.

Acid Etching, Dental↗

PubMedDate not supplied

Influence of dentin conditioning and contamination on the marginal integrity of sandwich Class II restorations.

This study investigated the influence of dentin conditioning and contamination on the marginal adaptation of Class II sandwich restorations. Large butt-joint MOD cavities with cervical margins located 1 mm below the CEJ were cut into 72 extracted human molars. Nine groups were filled using a total-bond technique with Z100 or a sandwich technique with either Vitremer or F2000 in combination with Z100. For all three material combinations three different pretreatments were compared: total etch, selective etch and dentin contamination with saliva and blood prior to primer/adhesive application. After water storage for 21 days and thermocycling (2000x, 5-55 degrees C) replicas were produced for quantitative marginal analysis in the SEM. Teeth were immersed in 0.5% basic fuchsin for 24 hours and dried. Percent dye penetration over the total marginal length was analyzed in three layers using a sequential grinding technique. Statistical analysis was performed using a two-way ANOVA. Post-hoc analyses were carried out with univariate Mann-Whitney-U-tests adjusting for multiple comparisons by a sequentially rejective test procedure (Bonferroni-Holm) at p < 0.05. Both F2000 and Vitremer sandwich restorations showed better marginal adaptation than Z100 total-bond restorations with all pretreatments. Acid etching of the dentin significantly influenced the marginal adaptation of Z100 total-bond restorations and Vitremer sandwich restorations. All types of restorations showed considerable microleakage. On contaminated dentin, sandwich restorations showed better marginal integrity than total-bond restorations. Marginal adaptation did not correspond with microleakage in all groups. In conclusion, F2000/Z100 and Vitremer/Z100 sandwich restorations show better marginal adaptation than Z100 total-bond restorations in large Class II cavities with cervical margins in dentin. Microleakage cannot predictably be prevented with the sandwich technique. Sandwich restorations seem to be less sensitive to contamination with saliva and blood.

Acid Etching, Dental↗

PubMedDate not supplied

Leucite-reinforced glass ceramic inlays and onlays after six years: clinical behavior.

Ceramic inlays are an esthetic substitute for large amalgam and other metallic restorations. This controlled clinical study evaluated the performance of IPS Empress inlays and onlays with cuspal replacements and proximal margins below the cementoenamel junction over six years of clinical service. Six dentists placed 96 ceramic restorations in 34 patients. Luting was accomplished using the enamel-etch-technique, a dentin bonding system (Syntac Classic) and four different composite systems. The restorations were assessed by two calibrated investigators using modified USPHS criteria at baseline (96 restorations), one (96), two (95), four (89) and six years (67). Seven of the 96 restorations investigated had to be replaced (failure rate 7%; Kaplan-Meier): Five inlays suffered cohesive bulk fractures and two teeth required endodontic treatment. After six years of clinical service, significant deterioration (Friedman 2-way ANOVA; p < 0.05) was found for marginal adaptation of the remaining restorations. Ninety-four percent of the surviving restorations exhibited marginal deficiencies, independent of the luting composite. Neither the absence of enamel margins, nor cuspal replacement significantly affected the quality of the restorations.

Acid Etching, Dental↗

PubMedDate not supplied

Evaluation of dental adhesive systems with amalgam and resin composite restorations: comparison of microleakage and bond strength results.

A variety of laboratory tests have been developed to assist in predicting the clinical performance of dental restorative materials. Additionally, more than one methodology is in use for many types of tests performed in vitro. This project assessed and compared results derived from two specific laboratory testing methods, one for bond strength and one for microleakage. Seven multi-purpose dental adhesives were tested with the two methodologies in both amalgam and resin composite restorations. Bond strength was determined with a punch-out method in sections of human molar dentin. Microleakage was analyzed with a digital imaging system (Image-Pro Plus, Version 1.3) to determine the extent of dye penetration in Class V preparations centered at the CEJ on both the buccal and lingual surfaces of human molar teeth. There were 32 treatment groups (n = 10); seven experimental (dental adhesives) and one control (copal varnish, 37% phosphoric acid) followed by restoration with either amalgam or resin composite. Specimens were thermocycled 500 times in 5 degrees and 55 degrees C water with a one-minute dwell time. Bond strength and microleakage values were determined for each group. ANOVA and Student-Newman-Keuls tests demonstrated an interaction between restorative material and adhesive system with a significant difference among adhesives (p < 0.05). Using a multi-purpose adhesive system resulted in both a statistically significant increase in bond strength and a statistically significant decrease in extent of microleakage (p < 0.05). The effect of the adhesive upon both microleakage and bond strength was greater in the resin composite restorations than in the amalgam restorations. Bond strength testing was more discriminating than microleakage evaluation in identifying differences among materials.

Analysis of Variance↗

PubMed2000

A comparison of the marginal and internal adaptation of amalgam and resin composite restorations in small to moderate-sized Class II preparations of conventional design.

OBJECTIVE: The purpose of this study was to compare the marginal and internal adaptation of a non-gamma-2 amalgam and an ultrafine compact-filled light-cured composite in small to moderate-sized Class II restorations of conventional design. METHOD AND MATERIALS: Fifty recently extracted human premolar and permanent molar teeth were selected for the study. The teeth were restored with either a non-gamma-2 amalgam alloy or a light-cured resin composite. The marginal adaptation of the restorative materials to the proximal surface outline form of each preparation was assessed. The mean percentages of perfect margins, marginal fissuring, and underfilled margins for the 2 restorative materials were recorded and statistically analyzed. RESULTS: Both materials performed equally well in the buccal and lingual segments of the proximal box. At the cervical margin, the resin composite restorations showed a significantly greater number of imperfect margins and marginal fissuring. The incidence of underfilled margins was low for both restorative materials even at the cervical margin. CONCLUSION: Although there was some cause for concern about the marginal adaptation of the resin composite restorations along the cervical margin, the findings support contemporary teaching that small to moderately sized conventional Class II preparations may justifiably be restored with an appropriate resin composite.

Analysis of Variance↗

PubMedDate not supplied

Cervical dentin hypersensitivity. Part I: The air indexing method.

The purpose of this article is to introduce an objective method for quantifying cervical dentin hypersensitivity. Air emissions from a standard air-water syringe or a syringe with a Fluid Control Block are directed toward the cervices of teeth at a 45-degree angle to the long axis of test teeth from a distance of 0.5 cm for 0.5 to 1.0 second. An air indexing method has been developed to quantify threshold patient response values for individual teeth to this defined air stimulus. The air indexing method, using the Fluid Control Block, offers the clinician objective information to compare cervical dentin hypersensitivity before and after treatment for this common, painful condition.

Air↗

PubMedDate not supplied

Cervical dentin hypersensitivity. Part II: Associations with abfractive lesions.

OBJECTIVE: The purpose of this retrospective study was to evaluate the association between cervical dentin hypersensitivity and the presence of abfractive lesions. METHOD AND MATERIALS: Written records and study casts for 250 active-care patients, selected alphabetically, were analyzed for the clinical detection of abfractive lesions and cervical dentin hypersensitivity from 1979 until 1996. Clinical diagnosis of abfractive lesions was made according to existing literature descriptions of these hard tissue lesions. Cervical dentin hypersensitivity was diagnosed when a verified positive threshold patient response was found during tooth evaluation by the air indexing method. Patient groups I and II were formed solely on the basis of the presence or absence, respectively, of a verified positive threshold patient response of cervical dentin to air. RESULTS: A significant association was found between air-indexed cervical hypersensitivity and the presence of abfractive lesions. The primary locations for both cervical hypersensitivity and abfractive lesions were the buccal surfaces of posterior teeth. CONCLUSION: This long-term retrospective study found a positive association between cervical dentin hypersensitivity and abfractive lesions. The correlative nature of this study suggests the need for further investigation.

Adolescent↗

PubMed1999

Demonstration of "vertical barrelling" using profilometry.

The aim of this study was to demonstrate the extent of tooth flexure under axial loading using profilometry. Fifteen extracted human permanent upper premolar teeth were embedded in hard die stone and divided into 3 groups. One group was left unprepared, the second group had artificial cervical saucer shaped lesions prepared and the final group had artificial cervical notch lesions prepared. The labial profile was taken using a diamond stylus mounted in a Profilometer. The teeth were then loaded in an axial direction to circa 670 N and the labial surface re-profiled 20 s after loading. The results indicate that changes occur in the labial profile of premolar teeth that are subjected to axial loading which could be considered to represent vertical barrelling. Changes in the profile of the artificial saucer and notch lesions prepared at the cervical region suggest that stresses would be generated on restorations of these lesions.

Bicuspid↗

PubMed2000

Does pretreatment of cavities effectively promote good marginal adaptation of glass-ionomer cements?

PURPOSE: The aim of this laboratory study was to evaluate the marginal sealing ability of four glass-ionomer cements in cervical restorations (Class V) using dye penetration. Two conventional (C-GIC) and two resin-modified (RM-GIC) cements were used either with or without dentin conditioning with polyacrylic acid. MATERIALS AND METHODS: 96 cervical cavities of standardized size were prepared in vitro in the vestibular and lingual portions at the cementoenamel level of 48 premolars. The coronal margins were prepared in enamel, the apical margins were localized in dentin. The 96 cavities were randomly divided into 4 groups of n = 24 each. The cavities of each group were filled with one of the test materials, and only half of the cavities received a dentin conditioning for 20 s with polyacrylic acids before filling. The fillings were finished with a set of abrasive disks 24 h after setting. The restored teeth were stored in saline for 4 weeks and subjected to dye penetration. The depth of dye penetration along the coronal and apical margin was measured on 4 longitudinal sections of each tooth with a semi-automatic image analysis system at 40x magnification. RESULTS: Mean depth of dye penetration ranged from 0 (ChemFil superior without conditioner) to 0.13 mm (ChemFil superior with conditioner) at enamel sites, and from 0.02 (Fuji II LC with conditioner) to 0.74 mm (ChemFil superior with and without conditioner) at dentin sites. CONCLUSION: The conditioning of the cavities before filling improved the marginal adaptation significantly only in the Ketac-Fil group. Conventional glass-ionomer cements (C-GIC) in general demonstrated a lower sealing ability than the light-activated, resin-modified cements (RM-GIC). The adaptation of Photac-Fil quick is best without pretreatment--as recommended by the manufacturer.

Acid Etching, Dental↗

PubMed2000

A clinical evaluation of Class II composites placed using a decoupling technique.

PURPOSE: This study was undertaken to evaluate the three-year clinical performance of Class II restorations of a fine particle hybrid composite placed using a decoupling placement technique, whereby polymerization shrinkage stresses at the cervical tooth-restoration interface were minimized by separating the initial gingival increment of composite from the body of the restoration using a polyurethane varnish. MATERIALS AND METHODS: The study was a practice-based explanatory, single-center clinical trial. A minimum of 40 Class II restorations of the material under investigation (Tetric) was required to be placed in predominantly molar teeth in selected patients. The restorations were placed using a decoupling incremental technique, bonding being accomplished using Syntac and Heliobond. The restorations were reviewed within 1 month of placement, thereafter at 18 months, then at 2 and 3 to 4 years using predetermined codes and criteria. Impressions and photographic records were used to obtain retrospective, third-party assessments of the restorations. RESULTS: Of 43 restorations originally placed and found to have ideal characteristics at baseline review, 41 (95%) were reviewed at 18 months, 36 (84%) at two years, and 31 (74%) at 3 to 4 years. None of the restorations were found to have suffered significant deterioration, notwithstanding three restorations having been lost to the study because of the replacement of part of the restored tooth for causes other than the catastrophic failure of the material. No secondary caries or postoperative sensitivity was recorded. CONCLUSION: It was concluded that the findings support the use of the material under investigation in the restoration of moderate- to large-sized Class II preparations in selected patients. The decoupling placement technique employed may be found to be an effective means to limit postoperative sensitivity and to contribute to the favorable in-service performance of restorations of the type investigated. Good practice would now require a multicentered, randomized controlled trial to investigate the effectiveness of the material and, in particular, the decoupling technique under the conditions of everyday practice.

Acrylates↗

PubMed2000

Marginal microleakage in bonded amalgam restorations: a combined in vivo and in vitro study.

PURPOSE: This study evaluated the marginal microleakage in bonded amalgam restorations in teeth extracted a month after restoration placement. MATERIALS AND METHODS: Nine teeth in a patient scheduled for complete extraction were selected. In each tooth, a buccal prepared cavity was treated with Scotchbond Plus and filled with high copper amalgam. In four teeth, a lingual unlined restoration was also prepared as control. A month later, all the teeth were extracted; seven teeth were immersed for 48 hours in a 0.05% basic fucsine dye solution and then sectioned. Sections were observed with a stereomicroscope at 10X. Results were statistically evaluated using a nonparametric Mann-Whitney test for independent data. The remaining two teeth were sectioned and observed using a scanning electron microscope (SEM). RESULTS: Stereomicroscopic analysis revealed that 80% of bonded specimens did not exhibit dye infiltration at the enamel margin; the same percentage of bonded specimens showed partial infiltration at the cervical margin. In the unlined control specimens, there was a complete dye infiltration at both margins. SEM analysis revealed a good adaptation between resin and tooth and between resin and amalgam. CONCLUSION: Bonded amalgam restorations are effective in reducing marginal microleakage, particularly at the enamel margin.

Aged↗

PubMed2000

Nanoleakage of cervical restorations of four dentin bonding systems.

PURPOSE: The aim of this study was to evaluate the degree of nanoleakage of restorations placed in cervical preparations with dentin bonding systems. MATERIALS AND METHODS: The dentin bonding systems used were Single Bond, One Coat Bond, Prime & Bond NT/NRC, and PermaQuik. Ten saucer-shaped cervical preparations were bonded with one of the dentin bonding systems and restored with Silux Plus resin composite in each group. After 24 hours storage in 37 degrees C water, restorations were finished and the surrounding tooth surfaces were coated with nail varnish. The samples were immersed in 50% w/v solution of silver nitrate for 24 hours, and exposed to photodeveloping solution for 8 hours. The samples were cut longitudinally through the center, polished, carbon coated and observed in a Field Emission SEM using backscattered electron mode. The degree of silver penetration along the preparation wall was observed and calculated as a percentage of the total preparation wall length. Results were analyzed by one-way ANOVA and LSD tests. RESULTS: PermaQuik demonstrated the lowest leakage score and the least silver deposition within the hybrid layer, while Prime & Bond NT/NRC showed the greatest leakage scores and the most silver deposition within the hybrid layer. Different nanoleakage patterns were observed for the different adhesive systems. CONCLUSION: First, the composition of each adhesive system may play a role in the different leakage patterns. Second, the current dentin bonding systems used in this study did not achieve perfect sealing at the restoration-dentin interface. This may influence the durability of the bond to dentin.

Acid Etching, Dental↗

PubMed2000

Bonding of a self-etching primer to non-carious cervical sclerotic dentin: interfacial ultrastructure and microtensile bond strength evaluation.

PURPOSE: The objectives of this study were 1) to examine the ultrastructural features of the resin-sclerotic dentin interface following the application of Clearfil Liner Bond II sigma to natural cervical wedge-shaped lesions, and 2) to evaluate the regional tensile bond strength of this self-etching primer at different locations on natural and artificially-created cervical lesions. MATERIALS AND METHODS: Deep cervical natural lesions were bonded using the self-etching primer. Micromorphology of the bonded interface at different locations within the lesions were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy/energy dispersive x-ray analysis (STEM/EDX). Ultrastructural features were further compared with the use of the same self-etching primer on artificial lesions created in sound cervical dentin. A nontrimming technique was used to evaluate the regional tensile bond strength from the occlusal, gingival, and the deepest central part of both natural and artificial cervical lesions. Beams with a mean area of 0.46 +/- 0.03 mm2 were prepared and were pulled to failure using a Bencor Multi-T testing device attached to an Instron universal tester. Bond strength results were evaluated using a two-way ANOVA design. RESULTS: A hypermineralized layer devoid of intact, banded collagen was invariably present on the surface of the natural lesions. Depending upon its thickness at different locations of the lesion, the action of a self-etching primer may be limited to this surface layer alone, producing a hybridized hypermineralized surface layer. Penetration of the self-etching primer into the underlying sclerotic dentin produced a hybridized complex containing a hybridized hypermineralized surface layer as well as a subsurface layer of hybridized intertubular dentin. Bacterial colonization of the lesion surface resulted in the formation of an additional zone of hybridized intermicrobial matrix over the surface of the lesions. Dentinal tubules remained blocked with sclerotic casts, and resin tags were rarely observed. Regional tensile bond strength results showed that the overall bond strength to natural sclerotic dentin was about 20% lower than sound cervical dentin, but was independent of the different locations within the lesions from which bond strength was evaluated. CONCLUSION: There were four factors that may have influenced the overall decrease in bond strength in natural cervical sclerotic lesions: a) the presence of a hybridized intermicrobial matrix together with entrapped bacteria may have weakened the bonds, b) inability of a self-etching primer to etch through a thick, hypermineralized surface layer, c) presence of a layer of possibly remineralized, denatured collagen at the base of the hypermineralized surface layer, and d) retention of acid-resistant sclerotic casts that obliterate the tubular lumina and prevent effective resin tag formation.

Acid Etching, Dental↗

PubMedDate not supplied

The effect of flexural load cycling on the microleakage of cervical resin composites.

Although several in vitro studies have attempted to investigate the microleakage of Class V resin composites under loading, the effect of load cycling on marginal seal is still unclear. This may be due to the fact that axial loads were applied to the specimens. This study investigated the effect of flexural loads on marginal sealing of cervical resin composites. One hundred and fifty cervical wedge-shaped cavities were restored with Clearfil Photo Bond, Clearfil Liner Bond 2, Scotchbond Multi-Purpose with 10% maleic acid, Scotchbond Multi-Purpose with 35% phosphoric acid or Mac-Bond 2 according to the manufacturers' instructions. After the restorations were finished, 10 specimens from each group were immersed in 0.5% basic fuchsin solution to examine microleakage. Prior to dye solution immersion, 20 specimens were subjected to flexural load cycling (1 mm labio-lingual or linguo-labial displacement at the incisal edge, 10,000 cycles, 1 cycle/second). The data were analyzed using the Kruskal-Wallis test and the Mann-Whitney U-test (p<0.05). When the flexural loads were not applied, both the incisal and apical margins showed good marginal sealing, regardless of the adhesive system used. Labio-lingual loading significantly deteriorated the marginal integrity at the incisal enamel margins, except for those restored with Clearfil Photo Bond. However, only Clearfil Photo Bond demonstrated a significant increase in microleakage along the apical dentin margins. Linguo-labial loading had no significant effect on the marginal seal.

Alkanes↗

PubMed2001

Cavity preparation devices: effect on microleakage of Class V resin-based composite restorations.

PURPOSE: To evaluate the effect of cavity preparation device (i.e. carbide bur, diamond bur, air abrasive, Sonicsys, and Er:YAG laser) on microleakage of Class V resin-based composite (RBC) restorations, the tooth restoration interface and dentin ultrastructure. MATERIALS AND METHODS: Eight groups (n=18) of 9 human molars each were prepared on the buccal and lingual surfaces for Class V RBC restorations using five preparation devices: Group 1: carbide bur #8 round; Group 2: diamond bur #801; Group 3: KCP 1000 air abrasion unit; Group 4: Sonicsys Approx.; Group 5: Er:YAG laser; Group 6: carbide bur plus air abrasive; Group 7: carbide bur plus laser, and Group 8: laser without etching. Circular cavity preparations, 3 mm diameter and 1.5 mm deep, were cut at the CEJ on the buccal and lingual surfaces of each tooth. A bevel was placed on the enamel margin. All cavities were restored using Single Bond adhesive system and Silux Plus according to manufacturer's directions, with the exception that no etchant was used with Group 8. After thermocycling, specimens were tested for microleakage using silver nitrate methodology. Dye penetration data was collected and subjected to non-parametric statistical analysis. SEM analysis of the dentin-RBC interface, as well as the effect of each cavity preparation device on the surface of dentin was performed. RESULTS: Microleakage did not occur in enamel for any method of cavity preparation when the enamel was etched prior to adhesive application. Kruskal-Wallis One-way ANOVA revealed differences in dentin microleakage among the tested groups at alpha=0.05. Mann-Whitney Test for Paired Comparisons at alpha=0.01 demonstrated significantly greater dentin microleakage in Groups 5 and 7 compared to all groups except Group 3 (air abrasive). Although Group 8 had the least microleakage in dentin, this was not significantly different from Groups 1, 2, 4 and 6. SEM observation revealed hybridization at the dentin-resin interface for all groups except for Group 8 (laser prepared, non-etched). Surface analysis showed differences related to the operating mode of each preparation device. CLINICAL SIGNIFICANCE: The method of cavity preparation did not affect microleakage in etched enamel. When using a laser for cavity preparation, enamel should be etched although not etching dentin may help to improve marginal seal.

Acid Etching, Dental↗

PubMed2001

Microleakage of Class II composite restorations.

PURPOSES: (1) To evaluate the in vitro sealing ability of several Class II resin restorations whose gingival extension of the proximal margin was apical to the cemento-enamel junction and in dentin and (2) to determine the effect of thermocycling on leakage into the resin-tooth interface. MATERIALS AND METHODS: Mesio-occlusal and distoocclusal preparations were made in extracted human molars. The gingival floor of the proximal box, was placed 1.0mm apical to the CEJ, and was prepared to a width of 1.5mm from the cavosurface margin to the axial wall. The teeth were restored with one of seven restorations (Z100 control, Z100, Wave, F2000, Surefil, Z100 and Vitrebond Sandwich A, Z100 and Vitrebond Sandwich B) using multiple incremental placement and materials. Following storage, half the samples were thermocycled. All 70 samples were stained using silver nitrate. The entire resin restoration was then removed from the proximal box ,and starting at the cavosurface margin the gingival floor was divided into three zones of 0.5 mm each and analyzed for dye penetration, using a novel technique which utilized the aid of computer imaging software and assessed both quantitatively and qualitatively. RESULTS: There was no statistical difference in leakage for all groups in Zone 1. For Zones 2 and 3, the groups utilizing glass-ionomer liner on the cavosurface margin had significantly less microleakage (P>0.05). Although the compomer/hybrid combination had low leakage values on average, the wide range of values led to unpredictable results. The flowable/hybrid combination and the packable composite performed less favorably. CLINICAL SIGNIFICANCE: This study demonstrated the difficulty in sealing a proximal dentin margin. However, the glass-ionomer/hybrid restorative techniques is the most likely to give successful clinical results.

Analysis of Variance↗