bluuebunny/crossref_metadata_2025 huggingface dataset:
Esthetic Smile Analysis of Maxillary Anterior Tooth Width: The Golden Percentage
Authors: SNOW STEPHEN R.
Published: July 2007

Abstract: With increasing application of cosmetic dental treatment comes the need for a greater understanding of esthetic principles. Scientific analysis of beautiful smiles has revealed repeatable, objective principles that can be systematically applied to evaluate and improve dental esthetics in predictable ways. Symmetry across the midline, anterior or central dominance, and regressive proportion are three composition elements required to create unity and esthetics in a smile. The Golden Proportion has been suggested as one possible mathematic analysis tool for assessing dominance and proportion‐ in the frontal view of the arrangement of maxillary teeth. It has proven to be controversial in developing esthetically beautiful smiles and cumbersome for evaluating symmetry.
Novel Approach to Measure Composite Conversion Kinetics during Exposure with Stepped or Continuous Light‐Curing
Authors: RUEGGEBERG FREDERICK A. , CAUGHMAN W. FRANK , CHAN DANIEL C. N.
Published: July 2007

Abstract: Purpose: The objective of this research was to evaluate a novel approach to monitor the polymerization reaction during a light‐curing exposure by using infrared (IR) spectroscopy.

Materials and Methods: An IR spectrometer was equipped to use an attenuated total reflectance (ATR) element as an IR‐active substrate. The uncured composite (Herculite XRV, Shade A2, Kerr, Orange, California) was placed against the crystal, and the IR spectrum was continuously obtained during various exposure scenarios. The degree of conversion and the maximum rate of reaction were monitored at 0 mm (top surface), 1 mm, 2 mm, and 3 mm beneath the surface. The exposure conditions included continuous 40‐second or 60‐second exposures at 100% intensity (800 mW/cm2) or a stepped output of 10 seconds at 17% maximal output (133 mW/cm2) followed by full output for the remainder of the 40‐second or 60‐second exposure (Elipar Highlight, ESPE, Norristown Pennsylvania). The results were analyzed using MANOVA with appropriate post hoc tests (p < .05).

Results: For 40‐second exposures, the peak conversion rates were significantly reduced (p < .05) when using the stepped exposure mode compared to the continuous exposure: 40‐second top surface: stepped = 5.5%/s ± 0.4, continuous = 10.5%/s ± 1.0; 1 mm step = 3.6%/s ± 0.4, continuous mode = 4.8%/s ± 0.2. The same trend was noted when using the 60‐second exposure. Equivalent conversion values (p > .05) beneath the surface between stepped and continuous exposure modes at similar depths 60 seconds after light initiation were only attained at 3 mm 4for the 40‐second exposure. However, using the 60‐second exposure, equivalent conversion values between step and continuous exposure modes at similar depths were obtained. Even with a reduced conversion rate at the surface using the stepped cure mode, polymerization shrinkage forces were sufficient to debond the specimens from the test crystal after only 20 seconds into the exposure. This result indicated that stress development in the curing composite was non‐uniform, and stress values developed at the surface of the restoration were the greatest.
Margin Gap Size of Ceramic Inlays Using Second‐Generation CAD/CAM Equipment
Authors: STURDEVANT JOHN R. , BAYNE STEPHEN C. , HEYMANN HARALD O.
Published: July 2007

Abstract: Objective: The goal of this study was to determine if the fit of second‐generation computer‐assisted design/computer‐assisted manufacturing (CAD/CAM) (CEREC 2, Sirona Dental Systems, Bensheim, Germany) inlays within Class II cavity preparations were within the range of 50 to 100 um and were equal or better to CEREC 1 inlays.

Materials and Methods: Extracted human molars free of surface defects and caries were prepared with standard mesio‐occlusodistal cavity preparations. Ceramic inlays were fabricated with CEREC 2 CAD/CAM equipment and seated into cavity preparations. Digital images were captured at 100 times magnification. Marginal gaps were measured with an image analysis program. For each restoration, gaps were measured at 12 locations along interproximal margins and 10 locations along occlusal margins.

Results: No difficulty occurred in seating any of the milled inlays. Average marginal gaps for occlusal (59 ± 35 um) and interproximal (97 ± 66 μm) margins were statistically different (t‐test, p < .01). Average marginal gap for all sites combined was 80 ± 57 μm. Marginal gap widths were smaller than those obtained from a similar study done earlier with the CEREC 1 unit for occlusal (89 ± 65 μm) and interproximal (105 ± 81 μm) margins. Ease of seating with CEREC 2 inlays was much better than with CEREC 1.
Esthetic Compomer Restorations in Posterior Teeth Using a New All‐in‐One Adhesive: Case Presentation
Authors: MANHART JUERGEN , HICKEL REINHARD
Published: July 2007

Abstract: Compomers have continually gained in importance since their introduction in 1993, especially because of their ease of handling. The main indications are cervical lesions, Class III restorations, and restorations in the primary dentition. To extend the indications of compomers to esthetic Class I and II restorations in the permanent dentition, improvements in wear resistance and bond strength need to be accomplished. Studies have shown an improved bond strength and less marginal gap formation between compomers and enamel and dentin with acid etching of the tooth before application of conventional mild self‐etching adhesives. Newly formulated, improved self‐etching adhesives with a higher demineralization potential recently have been developed. The objective of this case presentation is to demonstrate step‐by‐step the clinical procedure for the application of a newly developed self‐etching adhesive with high demineralization potential in combination with a compomer material in occlusal cavities.
In Vitro Penetration of the Pulp Chamber by Three Brands of Carbamide Peroxide
Authors: THITINANTHAPAN WARAPORN , SATAMANONT PIMONMAS , VONGSAVAN NOPPAKUN
Published: July 2007

Abstract: Purpose: Vital tooth bleaching has become a popular procedure for whitening teeth. Most home bleaching products contain 10% carbamide peroxide. The purpose of this in vitro study was to measure the quantity of hydrogen peroxide that reaches the pulp chamber from three carbamide peroxide products: Opalescence™, Sparkle™, and Rembrandt™.

Materials and Methods: Seventy roots of extracted premolars were amputated approximately 3 mm apical to the cementoenamel junction, and the pulp tissues were removed. They were divided into three experimental groups (n = 20) and a control group of 10 teeth. An acetate buffer solution was placed in the pulp chamber before the crown was exposed to the bleaching agent at 37°C for 25 minutes. The buffer solution was removed and reacted with leukocrystal violet and horseradish peroxidase. The optical density of blue color that developed was measured at a wavelength of 596 nm and read from a standard curve for hydrogen peroxide quantity.

Results: The measured amounts of hydrogen peroxide were 3.605 ± 1.405,1.282 ± 0.762, and 0.339 ± 0.251 pg for the Opalescence™, Sparkle™, and Rembrandt™ groups, respectively. A statistically significant difference in the hydrogen peroxide levels was observed by analysis of variance (p < .05) among the three groups. It was concluded that the penetration of commercial bleach ing products was different even though the products were labeled as having the same 10% carbamide peroxide.
Dental Discoloration: An Overview
Authors: HATTAB FAIEZ N. , QUDEIMAT MUAWIA A. , AL‐RIMAWI HALA S.
Published: July 2007

Abstract: Often the first evidence of variation from normal in human dentition is an observable difference in the color of the teeth. During the past decade, the demand for conservative esthetic dentistry has grown dramatically. Tooth discoloration is a frequent dental finding, associated with clinical and esthetic problems. It differs in etiology, appearance, composition, location, severity, and firmness in adherence to the tooth surface. Basically, there are two types of tooth discolorations: those caused by extrinsic factors and those caused by intrinsic congenital or systemic influence. The intensity of stains may be worsened if there are enamel defects. Tooth discoloration presents two major challenges to the dental team. The first challenge is to ascertain the cause of the stain; the second is its management.
Comparing the Perception of Dentists and Lay People to Altered Dental Esthetics
Authors: KOKICH VINCENT O. , ASUMAN KIYAK H. , SHAPIRO PETER A.
Published: July 2007

Abstract: Purpose: This study was designed to determine the perceptions of lay people and dental professionals with respect to minor variations in anterior tooth size and alignment and their relation to the surrounding soft tissues.

Materials and Methods: Smiling photographs were intentionally altered with one of eight common anterior esthetic discrepancies in varying degrees of deviation, including variations in crown length, crown width, incisor crown angulation, midline, open gingival embrasure, gingival margin, incisal plane, and gingiva‐to‐lip distance. Forty images were randomized in a questionnaire and rated according to attractiveness by three groups: orthodontists, general dentists, and lay people; 300 questionnaires were distributed.

Results: The response rate was 88.2% for orthodontists, 51.8% for general dentists, and 60.6% for lay people. The results demonstrated threshold levels of noticeable difference between the varying levels of discrepancy. A maxillary midline deviation of 4 mm was necessary before orthodontists rated it significantly less esthetic than the others. However, general dentists and lay people were unable to detect even a 4‐mm midline deviation. All three groups were able to distinguish a 2‐mm discrepancy in incisor crown angulation. An incisal plane cant of 1 mm as well as a 3‐mm narrowing in maxillary lateral incisor crown width were required by orthodontists and general dentists to be rated significantly less esthetic. Lay people were unable to detect an incisal plane asymmetry until it was 3 mm, or a lateral incisor narrowing until it reached 4 mm. Threshold levels for open gingival embrasure and gingiva‐to‐lip distance were both at 2 mm for the orthodontic group. Open gingival embrasure became detectable by the general dentists and lay people at 3 mm, whereas gingiva‐to‐lip distance was classified by these groups as noticeably unattractive at 4 mm.
Clinical Study of Tooth Shade Lightening from Dentist‐Supervised, Patient‐Applied Treatment with Two 10% Carbamide Peroxide Gels
Authors: CIBIRKA ROMAN M. , MYERS MICHAEL , DOWNEY MARY C. , NELSON STEVEN K. , BROWNING WILLIAM D. , HAWKINS ISAAC K. , DICKINSON GENE L.
Published: July 2007

Abstract: Purpose: Prescribed, patient‐applied tooth lightening agents, or nightguard vital bleaching, typically utilizes a 10% carbamide peroxide agent applied during nocturnal hours. The purpose of this randomized double‐blind study was to compare the amount of tooth color change in two groups of subjects using dentist‐supervised, patient‐applied 10% carbamide peroxide gel.

Materials and Methods: One group used Opalescence® (Ultradent Products Inc., South Jordan, Utah) and the other Nite White Excel® (Discus Dental, Inc., Los Angeles, California). Evaluation of tooth color for the six maxillary anterior teeth was done using a Vita shade guide at baseline, 1, 2, and 4 weeks. Subjects were instructed to apply the gel nocturnally using a custom‐made soft tray 8 hours per day for 2 weeks. The 16 tabs of the shade guide were ranked according to value from darkest to lightest. The number (1–16) that correlated to the shade tab selected as the match for each tooth was the outcome variable. A Kruskal‐Wallis one way analysis of variance on ranks was used.

Results: The test revealed no statistically significant difference between Opalescence® and NiteWhite® Excel for lightening the teeth (p= .807). The color change was still significant after 2 weeks without further bleaching activity. The baseline evaluation of the maxillary incisors and canines for all subjects, regardless of group, demonstrated a significant shade difference, with the canines being darker. This difference was not seen after 2 weeks of active bleaching or at the 4‐week evaluation.
Restoration of Extensive Erosion Areas Using an Indirect Composite Technique
Authors: KNIGHT JAMES S. , SNEED W. DAN
Published: July 2007

Cervical erosion defects, particularly those of extensive size that are located in an area where control of the operative field is difficult, can present a significant restorative challenge. This article describes an indirect restorative technique to solve this problem. Following tooth preparation, an indirect restoration is luted to the tooth and the margins are finished and polished. Using an indirect technique minimizes operative field isolation time and the total chairside time required to restore the tooth. Clinical cases are presented to illustrate this technique.

CLINICAL SIGNIFICANCE

An indirect composite restoration provides a useful treatment option when restoring extensive erosion defects in areas of difficult access.
Prevalence of Noncarious Cervical Lesions and Their Relation to Occlusal Aspects: A Clinical Study
Authors: TELLES DANIEL , PEGORARO LUIZ FERNANDO , PEREIRA JOSÉ CARLOS
Published: July 2007

Purpose: The purpose of this study was to assess noncarious cervical lesions in young patients and to establish a possible relation with occlusal aspects.

Materials and Methods: Forty‐eight dental students (28 males; 20 females) between the ages of 16 and 24 years, were investigated to verify the presence of noncarious cervical lesions and their relation to some occlusal aspects. The assessment involved a questionnaire, clinical examinations, and model analysis.

Results: The results indicated that the lower first molars (21.3%), the upper first molars (16.0%), the upper first premolars (12.8%), the lower first premolars (11.7%), and the lower second premolars (11.7%) were the teeth most affected by the lesions. Age was a significant factor with respect to the presence of lesions; the students with noncarious cervical lesions were older than the students who showed no lesions. Among the 79 teeth exhibiting lesions, 62 (78.5%) showed wear facets. In the group with lesions, the mean, per subject, was 15.0 teeth with wear facets, whereas in the group without lesions the mean was 10.8 teeth with wear facets per subject, suggesting that occlusal stress has some effect on lesion development.

CLINICAL SIGNIFICANCE

Noncarious cervical lesions are characterized by loss of tooth structure on the cervical area of the tooth and can result in esthetic problems for the patient, as well as discomfort due to the hyper‐sensibility that often occurs at the location of the lesion. The results obtained reinforce the multifactorial theory, shared by several authors, for the etiology of such lesions. However, as the limitations of each etiologic agent begin to be understood, there will be a decrease in the possibility of misleading interpretations of the result of present or future investigations.
Effect of Whitening Agents Containing Carbamide Peroxide on Cariogenic Bacteria
Authors: BENTLEY CAROLYN D. , LEONARD RALPH H. , CRAWFORD JAMES J.
Published: July 2007

Purpose: The purpose of this study was to investigate the in vitro antibacterial effects of three different carbamide peroxide products (Nitewhite®, Opalescence®, and Proxigel®) on cariogenic microorganisms (mutans streptococci [MS] and lactobacilli), and to evaluate the effects of a 10% carbamide peroxide solution (Proxigel®) on salivary levels of MS and lactobacilli clinically.

Materials and Methods: Growth inhibition studies were performed to determine the concentration and exposure time of carbamide peroxide to give total inhibition of recoverable growth of MS lactobacilli. Paraffin‐stimulated saliva samples were collected from subjects before and after 6 weeks of treatment with 10% carbamide peroxide in bleaching trays, and levels of MS and lactobacilli were determined.

Results: The growth inhibition studies showed no visible growth of MS or lactobacilli at 24‐, 48‐, or 72‐hour incubation, after a 2‐hour exposure to 1% carbamide peroxide. Identical results were obtained with all three carbamide peroxide products. In the clinical study, the mean salivary MS levels, expressed as logarithm colony‐forming units per milliliter (CFU/mL), were 5.38 for the pretreatment samples and 5.23 for the post‐treatment samples. The differences were not statistically significant (p > .05). However, there was a reduction in logarithm lactobacilli counts from a mean of 4.12 pretreatment to a mean of 2.74 post‐treatment. This was statistically significant (p < .05).

CLINICAL SIGNIFICANCE

This study indicates that carbamide peroxide solution is bacteriostatic for MS and lactobacilli in vitro and could reduce salivary levels of lactobacilli in vivo. Ten percent carbamide peroxide solution, when used in nightguard vital bleaching, is an antimicrobial that may be useful as an anticariogenic agent.
Critical Appraisal
Authors: Swift Edward J. , Rueggeberg Frederick A. , Caughman W. Frank
Published: July 2007

Surprisingly, many clinicians fail to realize that the quality of their direct, tooth‐colored restorations is directly related to the extent to which the polymer is cured, and that the extent of cure relies heavily on the quality of photoinitiating systems. In this second of two “Critical Appraisal” articles, attention is drawn to issues related to polymerization shrinkage and preparation design, variation in light intensity output, and direction of composite shrinkage. Many references presented are classic in the field, having been published over a decade ago, but these are still relevant to everyday clinical dentistry.
Enamel Microabrasion: A New Approach
Authors: CROLL THEODORE P. , HELPIN MARK L.
Published: July 2007

Enamel microabrasion is a proven method of removing superficial intrinsic enamel discoloration defects. The method is safe, easily performed, and causes no discomfort for the patient. A new commercially available microabrasion system has been introduced by Ultradent Products Inc. In addition, a new tooth isolation material is available, along with a visible light‐activated in‐office hydrogen peroxide solution. This article describes these new products and documents tooth‐color correction for two young patients using this new tooth‐color correction approach.

CLINICAL SIGNIFICANCE

Enamel microabrasion and vital bleaching can be used effectively to treat enamel dysmineralization and associated discoloration in children and adolescents.
Effects of Different Re‐Wetting Techniques on Dentin Shear Bond Strengths
Authors: RITTER ANDRÉ V. , HEYMANN HARALD O. , SWIFT EDWARD J. , PERDIGÃO JORGE , ROSA BRUNO T.
Published: July 2007

Purpose: For contemporary hydrophilic resin adhesive systems, bonding to dentin is improved if the substrate is maintained in a hydrated state following acid‐etching. The purpose of this study was to compare the dentin shear bond strengths of two single‐bottle adhesives (one acetone‐based and one ethanol‐based) applied under different etched‐dentin conditions: dry, wet, or dry and re‐wetted with different solutions.

Materials and Methods: Bovine incisors (N = 120) were mounted in acrylic, polished to 600‐grit, and randomly assigned to 12 groups (n = 10). Dentin was etched for 15 seconds using 35% phosphoric acid, rinsed, and either blot‐dried, air‐dried, or air‐dried and re‐wetted with different solutions (distilled water, Gluma Desensitizer, Aqua‐Prep, and 5% glutaraldehyde in water). Two adhesives (Single Bond and Prime & Bond NT) were applied to each of the surface conditions following manufacturers' instructions. After adhesive application and curing, composite was applied in a No. 5 gelatin capsule and light‐cured. Specimens were loaded in shear, using an Instron at 5 mm per minute. Shear bond strengths were calculated by dividing the failure load by the bonded surface area. Data were subjected to analysis of variance (ANOVA) and a post hoc Tukey test.

Results: Mean shear bond strengths ranged from 12.5 to 26.6 MPa for Single Bond and from 5.6 to 14.7 MPa for Prime & Bond NT. Significant differences were found in both groups of materials (p < .001). The three highest mean bond strengths were obtained (in order) on dentin that was re‐wetted with Gluma Desensitizer, re‐wetted with Aqua‐Prep, or never dried. Differences between these surface conditions were not statistically significant for either material.

CLINICAL SIGNIFICANCE

Different dentin surface conditions and re‐wetting techniques affected bond strengths for adhesives studied. Aqua‐Prep and Gluma Desensitizer can be successfully used as re‐wetting agents. The use of a re‐wetting agent may be beneficial when dentin is dried after acid‐etching and rinsing.
Bond Strength of Dual‐Cured Resin Cements to Human Teeth
Authors: LAFUENTE JOSE DAVID , CHAVES ANDREA , CARMIOL ROXANA
Published: July 2007

Purpose: This study evaluated the bond strength of four commercial resin luting cements to enamel and superficial dentin, using a second‐generation laboratory composite.

Materials and Methods: Forty teeth were embedded in acrylic: 20 had superficial dentin exposed; 20 had enamel exposed. Each group was divided into four subgroups (n = 5) to be bonded with Variolink II, Dual Cement, 2‐bond‐2, and Permalute System, using an inverted, truncated cone of pre‐cured Artglass that was placed over the resin cement with a load of 2 N for 2 seconds. Specimens were stored at 37°C in 100% relative humidity for 24 hours before being tested for tensile bond strength (MPa). Data were analyzed using a two‐way analysis of variance. Tukey‐Kramer intervals for comparisons among resin cements and bonding substrates were calculated at a .05 significance level.

Results: Significant differences were found among resin cements. Variolink II had statistically higher bond strength values for both substrates than the rest of the cements evaluated. When bonding was to enamel, all failures were cohesive in the composite, and when bonding was to dentin, some adhesive failures occurred at the resin cement‐dentin interface. Permalute System had higher bond strengths than 2‐bond‐2 and Dual Cement when bonded to enamel.

Conclusions: Variolink II and Permalute had statistically different bond strengths to enamel and dentin. Variolink II showed statistically higher values for dentin bonding than the other cements. Use of Variolink II and Permalute resulted in statistically higher bond strengths than the other two cements.

CLINICAL SIGNIFICANCE

Esthetic restorations, such as tooth‐colored inlays and onlays, veneers, and crowns without metal substructure, rely on bonding for success and must be cemented with a resin cement. Bond strength of the resin cement to the restoration and tooth structure affects the outcome of the restoration. Variolink II had significantly higher bond strengths to enamel and dentin than the other cements evaluated in this study.
Ceramometal Bonded Inlays and Onlays
Authors: ALBERS HARRY F.
Published: July 2007

Porcelain‐fused‐to‐metal (PFM) is presently the most popular crown and bridge technique. Its success is attributable to the use of a metal substructure to support the porcelain, resulting in good esthetics, limited ceramic flexure, and better longevity than all‐porcelain restorations. A new concept suggests encapsulating the metal substructure with ceramic and placing the insert under the occlusal surface, thereby combining the best properties of the esthetics of porcelain and the support of metal to achieve improved restorations.

CLINICAL SIGNIFICANCE

The ceramometal bonded restoration (CMBR) addresses the known limitations of PFMs by providing a more esthetic, more conservative, and more durable alternative. The CMBR eliminates the potential for tooth darkening, leaves more of the natural tooth intact, and offers good resistance to fracture or displacement under occlusal forces. This combination of features makes the CMBR inlay or onlay an excellent alternative for the conservative esthetic restoration of posterior teeth.
The Science of Communicating the Art of Esthetic Dentistry. Part I: Patient‐Dentist‐Patient Communication
Authors: MARZOLA RICCARDO , DERBABIAN KRIKOR , DONOVAN TERRY E. , ARCIDIACONO ALESSANDRO
Published: July 2007

Many contemporary restorative procedures are primarily esthetically driven, and patients have high expectations. It is imperative for the restorative dentist to understand patients' desires and expectations prior to initiating irreversible therapy. It is equally important for patients to understand the anatomic and technical limitations inherent with restorative therapy.

CLINICAL SIGNIFICANCE

This article describes several relatively straightforward techniques that can assist in dentist‐patient‐dentist communication and allow the patient to visualize a reasonable facsimile of the definitive result prior to initiation of irreversible therapy. By using these techniques where indicated, the frustrating cycle of rejection and failure may be avoided.
Shear Bond Strengths of One‐Bottle Adhesives to Oil‐Contaminated Enamel
Authors: ROSA BRUNO T. , HEYMANN HARALD O. , SWIFT EDWARD J. , PERDIGAO JORGE , RITTER ANDRE V.
Published: July 2007

Purpose: To evaluate resin bond strength to enamel contaminated with handpiece oil.

Materials and Methods: Bovine teeth were randomly assigned to six groups of 20 teeth each for treatment with one of six different bonding systems (five one‐bottle and one multibottle). For each system, 10 enamel specimens were contaminated with handpiece oil before acid‐etching and 10 were contaminated after acid‐etching. The enamel was etched for 15 seconds using 35% phosphoric acid. Following adhesive application, composite resin was bonded using a gelatin capsule technique. Shear bond strengths from the two contaminated groups were compared to bond strengths to uncontaminated enamel obtained from a previous study that was performed by the same group of investigators, using the same facility, materials, and methods.

Results: Two‐way analysis of variance (ANOVA) showed that the factor “surface contamination” did not have a significant effect on bond strength (p > .542). The type of adhesive and the interaction of adhesive and surface contamination were significant (p <.0001 and p <.003, respectively). When oil was applied before etching, mean bond strengths ranged from 18.0 ± 4.8 MPa for OptiBond SOLO (Kerr Corp., Orange, California) to 25.3 ± 5.6 MPa for Tenure Quik with Fluoride (Den‐Mat Corp., Santa Maria, California). With oil applied after etching, bond strengths ranged from 18.4 ± 8.0 MPa for Tenure Quik with Fluoride to 27.4 ± 5.4 MPa for Single Bond (3M Dental Products, St. Paul, Minnesota). For the same adhesive, comparing uncontaminated and “oil‐before‐etch” contaminated groups, the only statistically significant difference in bond strengths was for OptiBond SOLO: 21.8 ± 4.0 MPa (uncontaminated) versus 18.0 ± 4.8 MPa (oil before etch). Comparing uncontaminated and “oil‐after‐etch” groups, the only statistically significant difference was for Tenure: 24.5 ± 5.7 MPa (uncontaminated) and 18.4 ± 8.0 MPa (oil after etch).

CLINICAL SIGNIFICANCE

Surface contamination with handpiece lubricant oil does not impair appreciably the efficacy of the adhesives used in this study when bonding composite resin to enamel.
Amalgam Substitutes: A Critical Analysis
Authors: LUTZ FELIX , KREJCI IVO
Published: July 2007

Purpose: Quality standards for restorations recently have been defined in Switzerland. Amalgam substitutes must meet restoration Grade 2 requirements (i.e., pulp and dental hard substance must be preserved, and both form and function of the tooth have to be reconstituted). The pertinent operative technique has to be simple and amalgam‐like. A minimum service life of 8 years is required. This in vitro study investigated the clinical potential of several amalgam substitutes, taking into account the operative requirements, the defined restorative guidelines, and the required service life.

Materials and Methods: Potential amalgam substitutes evaluated in this study included compomers (Compoglass, Dyract, Dyract AP, Elan, F 2000) and resin‐based composites (Alert, Ariston, Definite, Nulite, Solitaire, Surefil). The composites Adaptic and Tetric Cream, using a simplified placement technique, were tested as negative and positive controls, respectively. Marginal adaptation and wear properties were measured in vitro in mixed Class II cavities. Relative radiopacity was measured in terms of millimeters of equivalent aluminum.

Results: All compomers showed a radiopacity of 2.5 mm or more aluminum. Only Dyract AP and Elan were more wear resistant than amalgam. After stressing, the percentage of continuous margin was at best 31% overall and 17% in dentin only. Among resin‐based composites, the minimum requirements of radiopacity were fulfilled only by Alert, Surefil, and Tetric. Only Definite, Surefil, Solitaire, and Tetric exhibited wear resistance greater than amalgam. After stressing, the best marginal qualities were 41% continuous margin overall, and 8% in dentin only.

CLINICAL SIGNIFICANCE

Based on the requirements set for amalgam substitutes, results for the materials tested in this study indicated poor marginal quality and potential risk of secondary caries. Currently, the use of amalgam substitutes for stress‐bearing restorations in permanent teeth cannot be recommended without serious cautions. This is particularly true if a dynamic performance quality of the restorations is demanded, which guarantees the achievement of the restorative targets for 8 years, according to recently adopted quality standards.
Small‐Diameter Implants: Indications and Contraindications
Authors: DAVARPANAH MITHRIDADE , MARTINEZ HENRY , TECUCIANU JEAN‐FRANCOIS , CELLETTI RENATO , LAZZARA RICHARD
Published: July 2007

The choice of implant diameter depends on the type of edentulousness, the volume of the residual bone, the amount of space available for the prosthetic reconstruction, the emergence profile, and the type of occlusion. Small‐diameter implants are indicated in specific clinical situations, for example, where there is reduced interradicular bone or a thin alveolar crest, and for the replacement of teeth with small cervical diameter. Before using a small‐diameter implant, the biomechanical risk factors must be carefully analyzed. Preliminary reports of this type of implant show good short‐ and medium‐term results.

CLINICAL SIGNIFICANCE

Specific clinical situations indicate the use of small‐diameter implants: a reduced amount of bone (thin alveolar crest) and where the replacement tooth requires a small cervical diameter. In some cases, the use of small‐diameter implants avoids bone reconstruction.
Scientifically Based Rationale and Protocol for Use of Modern Indirect Resin Inlays and Onlays
Authors: BLANK JEFF T.
Published: July 2007

The desire to place esthetically pleasing, conservative, functionally stable, posterior restorative materials has steadily increased over the past 20 years. The creation of successful dentin bonding adhesives and appropriate resin luting cements has paved the way for the development of a myriad of indirect resin‐based restorative materials. These materials have been specifically designed to overcome the negative attributes of their porcelain counterparts, and to simplify fabrication, insertion, and post‐delivery adjustments. Possibly like no other product before, these restorative materials have met with instant clinical acceptance by many practitioners, and concern exists that these materials have not been sufficiently studied to warrant such widespread acceptance. This article presents an overview of the history and development of resin‐based, esthetic, indirect systems, and offers the clinician a review of the literature supporting their role in posterior restorative dentistry. Additionally, a scientifically based protocol for preparation, impressing, provisionalization, and subsequent cementation and adjustment of indirect laboratory‐processed resin inlays and onlays is presented.

CLINICAL SIGNIFICANCE

This article reviews the history of indirect laboratory‐processed resin restorations, reviews available literature supporting their use, and presents a scientifically based protocol for their placement and use as a viable alternative for conservative reconstruction of posterior teeth.
In Vitro Evaluation of Margins of Replaced Resin‐Based Composite Restorations
Authors: GORDAN VALERIA V.
Published: July 2007

Purpose: To evaluate in vitro any increase in size of Class V resin‐based composite (RBC) restorations as a result of replacement.

Materials and Methods: For group 1, 20 Class V cavity preparations were prepared in extracted incisor and canine teeth. The cavosurface margin was prepared as a butt joint 90‐degree angle toward the occlusal wall. Impressions were made of all preparations with a polyvinyl siloxane material. The cavities then received a 1.5‐mm 45‐degree bevel at the cavosurface margin of the occlusal wall. Impressions were again made of the preparations. The cavities were then restored with a conventional multistep bonding system (Scotchbond Multi‐Purpose, 3M Dental Products, St. Paul, Minnesota) and a microfilled RBC (Silux Plus, 3M Dental Products). As a second part of the study (group 2), another 20 Class V cavity preparations were prepared. Half of the cavities received a bevel at the cavosurface margin of the occlusal wall, and half were finished with a butt joint. Impressions were made from all 20 specimens followed by resin‐based composite restoration in the same manner as previously described. All the restorations from both group 1 and group 2 were then removed with carbide burs. New impressions were made, and 100 stone models were fabricated. The perimeter and area of the cavity preparations, including the beveled area, were recorded using a video‐based imaging system equipped with macro lens, at 10 to 15 times magnification. Both perimeter and area of the postoperative cavity preparation were compared to the initial cavity size for both butt joint and bevel finishing.

Results: Intraclass correlation coefficient and paired t‐test showed no significant difference between the preoperative bevel type of cavity preparation and its postoperative counterparts for both group 1 and group 2 (p > .05). However, a significant increase in the size of the cavity preparation was found preoperatively when a bevel was placed at the cavosurface margin. Postoperatively, a significant increase in size of the cavities was found for butt joint type finishing for both area (p= .0001) and perimeter (p= .0001), compared to initial cavity size.

CLINICAL SIGNIFICANCE

This in vitro study showed that clinicians are likely to be more conservative when resin‐based composite restorations are removed if a bevel rather than a butt joint had been placed at the occlusal cavosurface margin. However, the study also showed that a significant amount of tooth structure is lost when a bevel is placed preoperatively at the occlusal cavosurface margin of a Class V resin‐based composite restoration.
The Science of Communicating the Art of Esthetic Dentistry. Part II: Diagnostic Provisional Restorations
Authors: DERBABIAN KRIKOR , MARZOLA RICCARDO , DONOVAN TERRY E. , CHO GEORGE C. , ARCIDIACONO ALESSANDRO
Published: July 2007

Provisional restorations fulfill many functions in restorative dentistry. Quality provisional restorations can provide the clinician, the patient, and the laboratory technician much valuable information prior to fabrication of the definitive restoration. Such diagnostic provisional restorations fabricated with acrylic resin are easily adjusted and modified until both esthetic and functional results are approved by the patient. Once this approval has been obtained, the definitive restorations can be fabricated with confidence, using the esthetic form of the provisional restorations as a blueprint.

CLINICAL SIGNIFICANCE

Routine use of provisional restorations for esthetic diagnostic purposes can prevent the destructive cycle of failure and frustration frequently experienced when performing elective esthetic restorative dentistry.
Effect of Whitening Agents on Dentin Bonding
Authors: SPYRIDES GEORGE M. , PERDIGÅO JORGE , PAGANI CLÓVIS , ARAÚJO MARIA AMÉLIA M. , SPYRIDES SILVANA M.M.
Published: July 2007

Background: Several studies have shown a reduction in enamel bond strengths when the bonding procedure is carried out immediately after vital bleaching with peroxides. This reduction in bond strengths has become a concern in cosmetic dentistry with the introduction of new “in‐office” and “waiting‐room” bleaching techniques. The aim of this in vitro study was to evaluate the effect of three bleaching regimens: 35% hydrogen peroxide (HP), 35% carbamide peroxide (CP), and 10% CP, on dentin bond strengths.

Materials and Methods: One hundred and twenty fresh bovine incisors were used in this study. The labial surface of each tooth was ground flat to expose dentin and was subsequently polished with 600‐grit wet silicon carbide paper. The remaining dentin thickness was monitored and kept at an average of 2 mm. The teeth were randomly assigned to four bleaching regimens (n = 30): (A) control, no bleaching treatment; (B) 35% HP for 30 minutes; (C) 35% CP for 30 minutes; and (D) 10% CP for 6 hours. For each group, half of the specimens (n = 15) were bonded with Single Bond/Z100 immediately after the bleaching treatment, whereas the other half was bonded after the specimens were stored for 1 week in artificial saliva at 37°C. The specimens were fractured in shear using an Instron machine.

Results: For the groups bonded immediately after bleaching, one‐way analysis of variance (ANOVA) followed by the Duncan's post hoc test revealed a statistically significant reduction in bond strengths in a range from 71% to 76%. For the groups bonded at 1 week, one‐way ANOVA showed that group B (35% HP for 30 min) resulted in the highest bond strengths, whereas 10% CP resulted in the lowest bond strengths. Student's t‐test showed that delayed bonding resulted in a significant increase in bond strengths for groups B (35% HP) and C (35% CP); whereas the group bleached with 10% CP (group D) remained in the same range obtained for immediate bonding. Storage in artificial saliva also affected the control group, reducing its bond strengths to 53% of the original.
Developments in Shrinkage Control of Adhesive Restoratives
Authors: DAUVILLIER BIBI S. , AARNTS MAXIM P. , FEILZER ALBERT J.
Published: July 2007

Purpose: This article reviews material properties and application techniques important in minimizing effects of polymerization shrinkage during the curing reaction of resin composite restorative materials used in adhesive dentistry.

Materials and Methods: Relevant scientific publications were critically reviewed.

Results: Since it was recognized that shrinkage, which takes place during the curing reaction of resin composite restorative materials, may cause severe problems in adhesive dentistry, considerable effort has been put into reducing the negative effects. The most important problem is the debonding of the restoration‐tooth interface, resulting in increased microleakage and, ultimately, in secondary caries. Despite all efforts, there is still no material or general application method that guarantees a leak‐proof and durable restoration.

CLINICAL SIGNIFICANCE

It is of the utmost importance that dental practitioners know how to deal with the problems related to resin composite shrinkage, so that they can choose the material and procedure most likely to produce a leak‐proof and durable restoration, maximizing the potential for clinical success.
Curing Dental Resins and Composites by Photopolymerization
Authors: STANSBURY JEFFREY W.
Published: July 2007

The development and continued evolution of photopolymerizable dental materials, particularly dental composite restoratives, represent a significant, practical advance for dentistry. The highly successful integration of the light‐activated curing process for dental applications is described in this review. The basic mechanisms by which the photoinitiators efficiently convert monomers into polymers are discussed along with the variety of factors that influence the photopolymerization process. The conventional camphorquinone‐amine visible light photoinitiator system used in most dental restorative materials is illustrated in addition to some alternative initiator systems that have been studied for dental materials applications.

CLINICAL SIGNIFICANCE

Photopolymerization has become an integral component of the practice of dentistry. A better appreciation of the photopolymerization process as well as its potential and limitations may aid the dentist in the delivery of both esthetic and restorative dental care.
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

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 SIGNIFICANCE

Polymerization 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

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 SIGNIFICANCE

Maximum 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

The 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 SIGNIFICANCE

Patients 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.