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Biomedical subjects

D Dietschi

Publications and source records attributed to D Dietschi.

At least 19 recordsLinked to original sources
PubMed1998

In vitro evaluation of marginal and internal adaptation of class II resin composite restorations after thermal and occlusal stressing.

The aim of this in vitro trial was to evaluate the external and internal adaptation of class II composite restorations to tooth structure by means of replica scanning electron microscope (SEM) observation. Standard MOD preparations were cut in human extracted teeth with margins located above and below the cementoenamel junction. Cavities were restored with either a direct multilayered technique, inlays (using conventional or dual DBA application) or prepolymerized composite inserts, using similar restorative material (Syntac, Variolink and Tetric). Evaluations were performed after mechanical and thermocycling. For the marginal adaptation in enamel, the bevelled margins of the direct group resulted in higher percentages of "continuity" (92.5% mesially and 94.6% distally), while the "marginal tooth fracture" was the most commonly found defect in groups with a butt preparation (up to 29.4%, with inserts). For the marginal adaptation in dentin, "continuity" percentages varied from 59% (inlay) to 87.9% (insert). As regards the internal adaptation, results for the whole dentin interface varied from 43.1% (inlay) to 63.9% (inlay with dual bonding) of "continuity". No regional difference in internal adaptation was found between the different preparation areas, except between gingival dentin and gingival enamel (44.9% vs. 80.7% of continuity, all group pooled data). Debonding occurred only at the dentin-restoration interface and consistently took place at the top of the hybrid layer. In the present experimental conditions, the inlay or insert techniques, which make use of the Dual bonding concept, proved to have the best potential to maintain the integrity of dentin-restoration interface.

Composite Resins↗
PubMed1998

Esthetic single-tooth replacement with implants: a team approach.

The range of indications for implant-borne prostheses in partially edentulous patients has expanded in recent years as a consequence of advances in regenerative techniques for bone and soft tissues. The esthetic demands of both patients and dentists have risen in parallel with these advances. Esthetic compromises in prostheses have become increasingly less tolerable, particularly in the anterior region of the maxilla. If the presenting situation is less than optimal, extensive preprosthetic measures may be required to prepare local tissues for acceptance of esthetically and functionally adequate prostheses. Particularly in difficult situations, collaboration by a team is recommended. The exchange of ideas and experience among specialists should begin as early as the treatment planning stage and extend over the entire course of therapy. The objective should be defined and the various steps of treatment should be coordinated with participation from all team members.

Adolescent↗
PubMed1998

Principles of proximal cavity preparation and finishing with ultrasonic diamond tips.

Conventional treatment of proximal cavities can result in significant damage to the adjacent dentition. This paper describes a recently developed technique of proximal cavity preparation and finishing by use of selectively diamond-coated, ultrasonically driven instruments. By using these instruments for composite, compomer, ceramic, amalgam, and even gold restorations, the inadvertent damage to neighboring teeth is completely avoided. This article demonstrates the effective utilization of the diamond-tipped ultrasonic instruments for the preparation of primary lesions and the replacement of existing restorations.

Dental Caries↗
PubMed1997

Current restorative modalities for young patients with missing anterior teeth.

The early loss of permanent teeth following trauma or congenital aplasia may be corrected by orthodontic or prosthetic means, sometimes combined with implant therapy. The orthodontic solution results usually in different anatomic, functional, and esthetic problems. Prosthetic and implant procedures, on the other hand, are very demanding and require long-term maintenance. Considering these limitations, a comprehensive diagnostic and treatment plan is mandatory to achieve the most satisfactory clinical result. Modern restorative modalities, such as recontouring, bleaching, and resin composite bonding, may improve the final clinical result after orthodontic space closure. In more difficult situations, veneers and crowns may also be indicated.

Adolescent↗
PubMed1997

Anatomical applications of a new direct Ceromer.

Composite resin materials have become the basic restorative materials of the modern aesthetics-oriented practice. However, the application of composite resin in posterior teeth remains a challenge as a result of its handling characteristics and chairside stratification. New ceramic optimized polymers (ceromers), such as Tetric Ceram (Ivoclar Vivadent, Amherst, NY), now offer versatility and improved handling properties in response to increasing clinical demand for producing high-quality natural restorations. With a well-designed instrumentation, the work of the clinician may be greatly facilitated. This article evaluates the selection and utilization of a direct ceromer material for posterior restorations and presents a predictable method to achieve aesthetic restorations.

Ceramics↗
PubMed1996

Esthetic restorations for posterior teeth: practical and clinical considerations.

The current abundance of posterior esthetic restorative materials and techniques may be confusing. This paper describes a simple and logical global concept that assists clinicians in choosing the appropriate therapeutic modality according to well-defined clinical criteria. Practical considerations about cavity preparation, base-lining, filling, luting, and finishing procedures are reviewed.

Bicuspid↗
PubMed1996

Current developments in composite materials and techniques.

General reduction of dental caries and patient interest in dental aesthetics have resulted in the development of new restorative materials and techniques. Composite materials and adhesive techniques have become the foundation of modern restorative dentistry. Mechanical performance, wear resistance, and aesthetic potential of composite resins have been significantly improved, and the material is now used in cases ranging from the restoration of initial decays and cosmetic corrections to the veneering in extended prosthetic rehabilitation. Polymerization shrinkage of the resin matrix remains a challenge and still imposes limitations in the application of direct techniques. The learning objective of this article is to review the most significant advances of composite materials and the importance of utilizing the available treatment options with discretion, selecting those which preserve the tooth structure and require the least maintenance.

Composite Resins↗
PubMed1995

Marginal adaptation and seal of direct and indirect Class II composite resin restorations: an in vitro evaluation.

The aim of this in vitro study was to evaluate the marginal adaptation and seal of posterior composite resin restorations made with direct (three-sited multilayering) or indirect (extraoral inlay) techniques. The influence on the marginal quality of the cervical finishing design (butt or beveled) and residual enamel height (0.5, 1.0, and 1.5 mm up to the cementoenamel junction) was also evaluated. This trial was performed on sound, freshly extracted human molars. When residual enamel was less than 1.0 mm in height or 0.5 mm in thickness, indirect restoration resulted in superior marginal quality. For preparations with sufficient residual enamel height (greater than 1.0 mm), beveling of gingival margins appeared mandatory for good adaptation of direct restorations and beneficial to the adaptation of indirect restorations. Residual gingival enamel height and thickness demonstrated an influence on marginal quality only in indirect restorations with butt margins.

Acrylic Resins↗
PubMed1995

Bonded to tooth ceramic restorations: in vitro evaluation of the efficiency and failure mode of two modern adhesives.

Dentinal seal and the internal adhesive interface of bonded tooth ceramic overlays were evaluated in vitro, using a dye infiltration test and direct-indirect SEM observations. The new adhesives such as Optibond or Scotchbond MP demonstrated better performances in dentin bonding than former adhesives. With the large cementing space (300 microns), a rigid set-up restraining compensatory phenomena between the restoration and the tooth proved again to negatively influence the dentinal seal of bonded ceramic overlays. In the present test conditions, dentin bonding of the new adhesives remains perfectible, even if the total etch technique is applied. Failure modes of Optibond and Scotchbond MP showed some specific features. For both brands, bonding failures occurred mainly between the hybrid layer and the overlaying resins; these are not of an artefactual nature, as was demonstrated by indirect SEM observations. The cohesiveness of the adhesive interface does not appear optimal at the present time; the need for stress reduction in the cementing space therefore remains of primary concern in dentin bonded restorations.

Ceramics↗
PubMed1995

Influence of the restorative technique and new adhesives on the dentin marginal seal and adaptation of resin composite Class II restorations: an in vitro evaluation.

The aim of the present in vitro study was to evaluate the marginal adaptation and seal of direct and indirect (inlay) Class II resin composite restorations made with Z100/Scotchbond MP or Herculite/Optibond. The quality of margins in dentin was assessed for restorations made with or without a lining of glass-ionomer cement or resin-modified glass-ionomer material. The restored teeth were submitted to thermocycling and then to replication for scanning electron microscopic observation and to a dye infiltration test. In the present test conditions, the inlay technique proved its superiority over the direct restorative method. The quality of the dentinal margin of restorations made with Z100/Scotchbond MP appeared also slightly better. Both the glass-ionomer cement and the resin-modified glass-ionomer material, when applied as a lining, increased leakage and downgraded marginal adaptation. The full bonding with modern adhesives appeared to be the most efficient way to enhance the marginal quality of both direct and indirect restorations.

Analysis of Variance↗
PubMed1995

Free-hand composite resin restorations: a key to anterior aesthetics.

The success of free-hand bonding in anterior teeth depends on a harmonious integration of various elements, including a thorough understanding of natural function, aesthetics, characteristics of current materials, and restorative techniques. The selection of composite brands which offer a variety of shades and provide several opacities is mandatory. By utilizing an anatomic stratification with successive layers of dentin, enamel, and incisal composite, a natural-appearing aesthetic result can be achieved in a relatively simple and predictable manner. Attentive use of finishing methods is still necessary for surface quality and natural appearance of the final restoration. Direct composite bonding remains an adequate therapeutic modality in traditional Class III to Class V and localized cosmetic restorations. It can satisfy most aesthetic demands, and it offers an affordable alternative to more invasive procedures, such as veneers and crowns. The learning objective of this article is to review anterior free-hand bonding utilizing composite restorative materials.

Composite Resins↗
PubMed1994

Comparison of the color stability of ten new-generation composites: an in vitro study.

OBJECTIVES: The aim of this in vitro study was to evaluate the color stability of modern light-cured composites when subjected to various physico-chemical and staining conditions. METHODS: Ten brands were evaluated including hybrids, microfine hybrids and microfilled composites. Some universal shade samples underwent only staining tests, while others were subjected to one of the following experimental conditions: thermocycling, postcuring, polishing or a 1 wk immersion in saline, prior to staining. The coloring solutions used for the staining tests were: coffee, E 110 food dye, vinegar and erythrosin. A colorimetric evaluation according to the CIE L*a*b* system was performed after experimental periods of 1 and 3 wk. RESULTS: Erythrosin caused the greatest color change for the composites tested. A reduced susceptibility to staining was observed where surfaces had been polished. Low water sorption, a high filler-resin ratio, reduced particle size and hardness, and an optimal filler-matrix coupling system were related to improved composite resistance to discoloration. SIGNIFICANCE: Resistance of modern composites to discolorations still depends on their structure and manipulation.

Absorption↗
PubMed1994

Recent trends in esthetic restorations for posterior teeth.

The increase in the demands made by patients for esthetic or metal-free restorations, together with the ever-growing interest shown by the dental profession for tooth-colored materials and techniques, led to the current development of posterior adhesive restorations. This paper reviews critical elements such as adhesion to dental hard tissues as well as current properties of bases/liners, filling materials, and luting materials. A rationale for the successful use of currently available restorative systems is presented.

Bicuspid↗
PubMed1993

An in vitro study of parameters related to marginal and internal seal of bonded restorations.

The wall-to-wall contraction of the cementing layer of bonded restorations is compensated for mainly by elastic and plastic tooth substrate-cement deformation but may result in adhesive fracture. Occlusally flattened teeth and corresponding computer-designed onlays, both positioned in a special device, were used to study marginal and internal seal of the adhesive interface with respect to four variables: rigidity of the restoration-substrate setup, cement thickness, adhesive configuration (enamel-dentin ratio and bonding agent), and luting agent. The results of dye infiltration tests revealed the significant influence of the adhesive configuration and rigidity of the setup. A high enamel-dentin ratio, use of a dentinal adhesive on dentinal margins and relative restoration-substrate "mobility" are required to preserve satisfactory marginal seal. However, in the present experimental conditions, no statistically significant differences were found among the diverse cement thicknesses or the luting agents evaluated.

Composite Resins↗