bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization Contraction Stress of Resin Composite Restorations in a Model Class I Cavity Configuration Using Photoelastic Analysis
Authors: KINOMOTO YOSHIFUMI , TORII MITSUO , TAKESHIGE FUMIO , EBISU SHIGEYUKI 
Published: July 2007

ABSTRACT Purpose: An important factor that contributes to deterioration of resin composite restorations is contraction stress that occurs during polymerization. The purpose of this article is to familiarize the clinician with the characteristics of contraction stress by visualizing the stresses associated with this invisible and complex phenomenon. Materials and Methods: Internal residual stresses generated during polymerization of resin composite restorations were determined using micro‐photoelastic analysis. Butt‐joint preparations simulating Class I restorations (2.0 mm ± 5.0 mm, 2.0 mm in depth) were prepared in three types of substrates (bovine teeth, posterior composite resin, and transparent composite resin) and were used to examine contraction stress in and around the preparations. Three types of composite materials (a posterior composite, a self‐cured transparent composite, and a light‐cured transparent composite) were used as the restorative materials. The self‐cured composite is an experimental material, and the others are commercial products. After treatment of the preparation walls with a bonding system, the preparations were bulk‐filled with composite. Specimens for photo‐elastic analysis, were prepared by cutting sections perpendicular to the long axis of the preparation. Fringe patterns for directions and magnitudes of stresses were obtained using transmitted and reflected polarized light with polarizing microscopes. Then, the photoelastic analysis was performed to examine stresses in and around the preparations. Results: When cavity preparations in bovine teeth were filled with light‐cured composite, a gap was formed between the dentinal wall and the composite restorative material, resulting in very low stress within the restoration. When cavity preparations in the posterior composite models were filled with either self‐cured or light‐cured composite, the stress distribution in the two composites was similar, but the magnitude of the stress was greater in the light‐cured material. When preparations in the transparent composite models were filled with posterior composite and light‐cured transparent composite material, significant stress was generated in the preparation models simulating tooth structure, owing to the contraction of both restorative materials.CLINICAL SIGNIFICANCEPolymerization contraction stress is an undesirable and inevitable characteristic of adhesive restorations encountered in clinical dentistry that may compromise restoration success. Clinicians must understand the concept of polymerization contraction stress and realize that the quality of composite resin restorations depends on successful management of these stresses.
Effect of Ramped Light Intensity on Polymerization Force and Conversion in a Photoactivated Composite
Authors: BOUSCHLICHER MURRAY R. , RUEGGEBERG FREDERICK A. 
Published: July 2007

ABSTRACT Purpose: This study evaluated the effect of ramped light intensity on the polymerization shrinkage forces and degrees of conversion (DC) of a hybrid composite. Materials and Methods: Composite samples were bonded between two steel rods (2.50 mm diameter, 1.25 mm apart, configuration factor = 1.0) mounted in a universal testing machine using a constant displacement mode. Polymerization contraction force was recorded for 250 seconds under four light exposure conditions: group 1, STD: (40 s ± 800 mW/cm2); group 2, EXP: (150 mW/cm2 logarithmic increase to 800 mW/cm2 over 15 s) + (25 s ± 800 mW/cm2); group 3, 2‐STEP: (10 s × 150 mW/cm2) + (30 s × 800 mW/cm2); group 4, MED: (80 s × 400 mW/cm2). Maximum curing force (N250s) and maximum force rate of the four groups were compared using one‐way analysis of variance (ANOVA) (α= 0.05) and the Tukey test. Degrees of conversion obtained with STD, EXP, and MED cure modes were evaluated at three depths (top surface, 1 mm, and 2 mm) using Fourier transform infrared spectroscopy (FTIR). Results: Maximum rates of polymerization shrinkage force development and standard deviations (SD), in ascending order, were group 4, MED: 0.33 ± 0.03 N/s; group 2, EXP: 0.35 ± 0.06 N/s; group 1, STD: 0.44 ± 0.03 N/s; and group 3, 2‐STEP: 0.46 ± 0.07 N/s. Maximum rates of polymerization shrinkage force development of group 2, EXP and group 4, MED were statistically equivalent and lower than those of group 1, STD and group 3, 2‐STEP. Maximum shrinkage forces (± SD), in ascending order, were group 2, EXP: 20.4 ± 2.5 N; group 4, MED: 25.8 ± 1.0 N; group 3, 2‐STEP: 27.4 ± 5.8 N, and group 1, STD: 30.5 ± 2.7 N. Maximum force of the EXP mode was statistically lower than MED, 2‐STEP, and STD curing modes. The EXP ramp was successful in reducing the conversion rate at the top surface and at 1.0‐mm depth, but it did not affect the total conversion compared to the STD 40‐second cure mode. There was no difference in DC at the top surface and 1‐mm depth with mode of cure. The MED cure mode resulted in a higher DC than the EXP mode at a depth of 2 mm.CLINICAL SIGNIFICANCEMaximum shrinkage force and force rate exhibited during the first 250 seconds of polymerization were significantly lower using a ramped light intensity exposure. Ramped light intensity decreased conversion rate at the top surface and at 1.0‐mm depth and did not affect the total extent of conversion compared to a standard 40‐secondY single‐intensity cure mode. The slower conversion rate resulting from ramped light intensity helped to reduce the rate and maximum polymerization stress, but would not be expected to compromise the physical properties for the restorative material, since similar degrees of conversion were obtained.
Treatment Planning for Porcelain Veneer Restoration of Crowded Teeth by Modifying Stone Models
Authors: CUTBIRTH STEVEN T. 
Published: July 2007

ABSTRACTThe three‐dimensional result attainable through porcelain veneer restoration of crowded teeth can be preoperatively determined by diagnostically altering stone study models of the patient's dentition. Techniques for diagnostically preparing and waxing the stone dental models are described in this article, along with the corresponding postoperative restorative results of representative cases.CLINICAL SIGNIFICANCEPatients with malaligned teeth who are not willing or able to undergo straightening of their teeth with orthodontics, nonetheless may be able to attain straight teeth concomitant with the restoration of their teeth with modified porcelain veneer restorations. This article describes a straight‐forward treatment planning technique for altering study casts preoperatively, to accurately predict and guide the postoperative outcome.
Four‐Year Clinical Evaluation of Posterior Resin‐Based Composite Restorations Placed Using the Total‐Etch Technique
Authors: BARATIERI LUIZ NARCISO , RITTER ANDRÉ V. 
Published: July 2007

ABSTRACT Purpose: To report the 4‐year clinical performance of posterior resin‐based composite restorations placed using the total‐etch technique. Materials and Methods: Over a period of 1 year, 726 restorations (248 molars, 478 premolars; 260 Class I, 466 Class II; 540 replacements, 186 primary decay) were placed on conservative preparations, using the incremental placement technique in a clinical environment. Baseline data were collected, and the restorations were evaluated after 4 years. Z100 and Scotchbond Multipurpose (SBMP) (3M Dental Products, St. Paul, Minnesota) were used as the restorative system. The criteria evaluated were color match, marginal adaptation, anatomic form, cavosurface marginal discoloration, axial contour, interproximal contact, secondary caries, postoperative sensitivity, and tooth vitality. Results: At baseline, 24% of the teeth restored presented postoperative sensitivity; 86% of the sensitive teeth were from the replacement group. At 4 years, all teeth were vital to cold test. Eighteen restorations (2.5%) presented clinically detectable marginal fracture. The shade was acceptable in all restorations. Cavosurface marginal discoloration was observed in 47 restorations (6.5% bravo scores). Axial contour, interproximal contact, and marginal adaptation received 100% alfa scores. No secondary caries was diagnosed in any of the teeth examined. None of the examined restorations required replacement.CLINICAL SIGNIFICANCEUnder controlled clinical conditions, posterior resin‐based composite restorations placed with the total‐etch technique and restorative Z1OO/SBMP have the potential to present a high success rate at 4 years. None of the examined restorations required replacement, and there was no clinically detectable wear in any of the restorations. Simultaneous etching of enamel and dentin followed by the application of a resin adhesive can be considered an adequate modality of pulp protection in nonexposed tooth preparations.
Anterior Esthetic Rehabilitation on Teeth and Dental Implants Optimized with Procera® Technology: A Case Report
Authors: BONNARD PASCAL , HERMANS MARC , ADRIAENSSENS PHILIPPE , DAELEMANS PHILIPPE , MALEVEZ CHANTAL 
Published: July 2007

ABSTRACTWith the latest developments of the Procera® system, all‐ceramic crowns have become an attractive solution to provide functional and esthetic rehabilitation on teeth and dental implants. The Procera AllCeram crown and Procera Abutment embrace the concept of computer‐assisted design and computer‐assisted machining (CAD/CAM) and can be used together for optimal esthetic result. The purpose of this case report was to illustrate the advantages of these new components for complex anterior rehabilitation. Three natural teeth and a Procera Abutment were restored using four Procera AllCeram crowns. Treatment planning and esthetic benefits are discussed.CLINICAL SIGNIFICANCEFor complex anterior rehabilitations, the Procera system fulfills both functional and esthetic objectives, providing a new way in the field of esthetic and restorative dentistry. Nevertheless, planning and preparation stages are decisive for successful treatment.
Periosteal Connective Tissue Grafting or Root Coverage with Enamel Matrix Derivative: A Case Report
Authors: ITO KOICHI , AKUTAGAWA HIDEYASU 
Published: July 2007

ABSTRACTA 24‐year‐old female patient presented for the resolution of esthetic concerns associated with wide gingival recession facial to the maxillary left central incisor before orthodontic treatment. A periosteal connective tissue graft in conjunction with an enamel matrix derivative was used to achieve root coverage. This technique achieved healthy thick keratinized tissue coverage of the root surfaces and effectively improved the esthetics. These satisfactory clinical results have been maintained for 18 months, even through active orthodontic treatment.CLINICAL SIGNIFICANCEThis case report demonstrates an innovative approach to root coverage that uses an enamel matrix derivative in conjunction with periosteal connective tissue grafting. Although there is no absolute clinical evidence that the enamel matrix derivative contributed to the final outcome, the results are encouraging and should be pursued through case‐controlled clinical trials.
Maximizing Esthetic Results in Posterior Restorations Using Composite Opaquers
Authors: DIAS WALTER R.L. , PEREIRA PATRICIA N.R. , SWIFT EDWARD J. 
Published: July 2007

ABSTRACTAfter removal of caries or a faulty existing restoration in a posterior tooth, frequently the pulpal floor is a dark substrate. Composites are translucent by nature, and even the more opaque shades transmit nearly 60% of visible light, meaning that composites require a certain thickness to maintain their intended shade, especially if the underlying substrate is particularly dark. Depending on the intensity of the dark substrate, even relatively thick composite restorations may not be capable of disguising the discolored dentin underneath. The substrate absorbs a significant part of the light that would otherwise reflect toward the occlusal surface, and the restoration has a nonvital monochromatic grayish color. Opaquers and tints (color modifiers) may be extremely useful to overcome this situation. In this study, composite restorations were placed in extracted teeth to demonstrate that the final esthetic results rely upon the optical properties of the background as well as those of the composite material itself. Preparations with simulated dark pulpal floors were restored without the use of opaquers and tint modifiers. After tooth hydration, the final shade was recorded with photographs. The restoration was removed and a new restoration was placed, but this time with a technique involving opaquer and tints. This article compares and discusses the outcomes of these two procedures.CLINICAL SIGNIFICANCEThis demonstration shows a simple technique that can help dentists obtain predictable esthetic results in their daily practice with posterior composite restorations.
Fabrication of Direct Fiber‐Reinforced Posts: A Structural Design Concept
Authors: TERRY DOUGLAS A. , TRIOLO PETER T. , SWIFT EDWARD J. 
Published: July 2007

ABSTRACTAs the clinician continues the quest for optimal functional and esthetic success of a tooth‐restorative complex, the current selection of restorative materials and techniques may prove overwhelming. Although no single system provides the ideal restorative solution for every clinical circumstance, understanding of general design criteria and the components for the various post and core systems available allow the clinician to appropriately select the method and materials compatible with the existing tooth structure and desired result. This article provides a discussion of the various post and core systems, the methods and materials inherent in these systems, and general design principles. Using that basic information and clinical experience, the authors offer an alternative procedure for the rehabilitation of the intraradicular anatomy of the post‐endodontic channel with a direct composite resin–the fiber‐reinforced post and core system.CLINICAL SIGNIFICANCEUsing improved restorative materials that simulate the physical properties and other characteristics of natural teeth in combination with the proper design principles, the clinician can develop a tooth‐restorative complex with optimal functional and esthetic results.
Simple Technique to Fabricate Provisional Restorations for Porcelain Veneers
Authors: DAN SNEED W. , KNIGHT JAMES S. 
Published: July 2007

ABSTRACTFabrication of provisional restorations for teeth prepared to receive porcelain veneers can be a time‐consuming and difficult task. This article describes a simple, quick, and predictable procedure to make these restorations. A clinical case is presented to illustrate the technique.
Effect of Light Power Density on Development of Elastic Modulus of a Model Light‐Activated Composite during Polymerization
Authors: SAKAGUCHI RONALD L. , FERRACANE JACK L. 
Published: July 2007

ABSTRACT Purpose: Elastic modulus development during polymerization of a composite is a measure of the polymerization maturity and the restoration's ability to transfer stress to enamel and dentin. The characteristics of elastic modulus development in real time during cure are largely unknown. The purpose of this study was to evaluate the effect of light power density and total energy density on the early development of elastic modulus for a light‐activated composite. Methods: Cylindrical specimens of a model hybrid composite were tested in flexure in a dynamic mechanical analyzer (DMA). Specimens were light‐activated (Variable Intensity Polymerizer, Bisco, Itasca, Illinois) for 60 seconds. Elastic modulus was measured continuously for 5 minutes from the start of light activation. Development of elastic modulus was assessed for six different light power densities and two reduced power density levels given at longer exposure duration to provide similar energy density values. One‐way analysis of variance with Tukey's post hoc comparison test was used to evaluate significant differences of elastic modulus at p= .05. Results: The rates of elastic modulus development and final moduli were dependent on the light power density applied. Composite specimens cured by equivalent energy densities using short times and high power density or long times and low power density produced equivalent elastic moduli. Elastic moduli for emitted power densities between 400 and 600 mW/cm2 (160–260 mW/cm2 measured at the specimen surface) were not significantly different (p > .05). Conclusions: Light power densities greater than 160 mW/cm2 measured at the specimen surface resulted in elastic moduli that were not significantly different. Equivalent energy densities produced comparable elastic moduli.
Nightguard Vital Bleaching and Its Effect on Enamel Surface Morphology
Authors: LEONARD RALPH H. , EAGLE JAMES C. , GARLAND GLENN E. , MATTHEWS KEVIN P. , RUDD ANDY L. , PHILLIPS CEIB 
Published: July 2007

ABSTRACT Background: The effect that nightguard vital bleaching (NGVB) has on enamel surface morphology is a subject of debate. Previous studies that have evaluated the effect of NGVB on the enamel surface report minimal changes to changes that appear to worsen post‐treatment. The purpose of this in vivo NGVB study was to evaluate by scanning electron microscopy (SEM) the effects that 10% carbamide peroxide has on enamel morphology after 2 weeks of treatment and at 6 months post‐treatment. Materials and Methods: Ten patients participated in the study. Each participant wore a guard filled with an active whitening solution for 8 to 10 hours per day for 14 treatment days. An impression of the study teeth (maxillary incisors) was taken at baseline, after 14 days of treatment, and at 6 months post‐treatment, and an epoxy cast made. The epoxy casts were prepared for viewing under the SEM and photographs were taken at 200 times and 2000 times magnification. Six examiners evaluated changes in enamel surface morphology by comparing the SEM photographs taken at baseline, on treatment day 14, and at 6 months post‐treatment. Still masked, the examiners also compared each patient's baseline: treatment day 14 and baseline: 6 months post‐treatment photographs with photographs of a known standard. Results: This in vivo study demonstrated that a 14‐day regimen of NGVB using a 10% carbamide peroxide solution had minimal effect on the surface morphology of enamel and that the effects did not worsen over time.
INFLUENCE OF LIGHT INTENSITY ON TWO RESTORATIVE SYSTEMS
Authors: Unterbrink G.L. , Muessner R. 
Published: July 2007

ABSTRACT Objective: This in vitro study examined the effect of light intensity variations on several properties of two restorative systems. Materials and Methods: Two resin composite systems (Tetric, Ivoclar Vivadent, Schaan, Liechtenstein; 2100, 3M Dental Products Division, St. Paul, Minnesota) and two dentin bonding agents (Syntac, Ivoclar Vivadent; Scotchbond Multi‐Purpose, 3M Dental) were used. To evaluate marginal gap formation in dentin cavities (with a C factor of 2.5), 48 bovine incisors were embedded in epoxy resin. The labial enamel was removed, and the dentin surface was polished to 600‐grit. Preparations were made in dentin and restored using one of four combinations of bonding system and composite. The composite was polymerized with either a high‐intensity lamp (450 mW/cm2) or a low‐intensity lamp (250 mW/cm2). After storage in water for approximately 60 minutes, the surfaces of the samples were prepared for electron microscopy analysis. Also, the flexural strength and modulus of each composite were determined at 30 minutes and 24 hours after polymerization with either the high‐ or low‐intensity light. Volumetric shrinkage was measured using the density method at four time periods for both light intensities and for wet versus dry storage. Finally, Vickers hardness profiles were evaluated to determine depth of cure. Results: Marginal analysis showed that 2100, when used with either Scotch‐bond Multi‐Purpose or Syntac, had an increased incidence of gap formation when polymerized with the high‐intensity light. Tetric had better marginal adaptation than 2100, when used with either dentin bonding agent, and with both light intensities. The flexural strength and modulus of both composites were lower with low‐intensity light‐curing. There were no differences in volumetric shrinkage or depth of cure related to curing method for either composite. Conclusions: The results of this study suggest that marginal quality may be reduced when a high‐intensity light is used to cure composite. Also, the light intensity influences development of the elastic modulus and, therefore, affects shrinkage stress in the composite. The two composites tested in this study responded differently to the different methods of light‐curing. In general, Z100 showed inferior properties than Tetric when cured with either high‐ or low‐intensity light, for both marginal integrity and the flexural modulus and strength. Finally, with a polymerization time of 40 seconds, the composites were equally well cured to a depth of 4.5 mm, regardless of the light intensity used.
PHYSICAL PROPERTIES OF COMPOSITES CURED WITH CONVENTIONAL LIGHT OR ARGON LASER
Authors: Cobb D.S. , Vargas M.A. , Rundle T. 
Published: July 2007

ABSTRACT Objective: This study evaluated various physical properties of two resin composites polymerized by either an argon laser or a conventional visible light. Materials and Methods: A hybrid composite, Herculite XRV (Kerr Corp., Orange, California), and a microfill composite, Durafill VS (Kulzer, Wehrheim, Germany), were used in this study. Three physical properties, diametral tensile strength, compressive strength, and flexural strength, were tested. Five specimens of each composite resin were made for each set of physical properties tested, for a total of 18 groups and 90 specimens. Specimens were fabricated according to the American National Standards Institute and American Dental Association Specification No. 27 for each property tested. The composite was polymerized with either an argon laser (power density of 1000 mW/cm2) for 10 or 20 seconds or a conventional visible light (power density of 354 mW/cm2) for 40 seconds. Specimens were stored in water in light‐proof containers at 37°C for 7 days before testing with a Zwick (Atlanta, Georgia) universal testing machine. Results: The physical properties of Herculite XRV were not affected by the light source or exposure time. For Durafill VS, no significant differences were observed for the diametral tensile strength whether the argon laser or conventional light was used. However, the flexural strength of the microfill was significantly lower when polymerized with the argon laser a t 10 seconds compared with the two other curing methods (20‐second laser cure, 40‐second conventional cure). Also, the compressive strength of Durafill VS polymerized with the argon laser a t 10 seconds was significantly lower than when it was cured with the conventional light for 40 seconds. Conclusions: Hybrid and microfill resin composites cured with an argon laser for 20 seconds had physical properties comparable to composites polymerized with a conventional visible light unit for 40 seconds. Therefore, with adequate exposure time, the argon laser is a potential alternative to conventional visible light‐curing.