Effect of remaining coronal structure on the resistance to fracture of crowned endodontically treated maxillary first premolars.

Objective: Endodontically treated maxillary first premolars present a restorative challenge. The objective of the present study was to assess the resistance to fracture of crowned endodontically treated maxillary first premolars under simulated occlusal load, while preserving various degrees of remaining coronal structure.

Methods And Materials: The study consisted of 50 intact maxillary first premolars with bifurcated roots and similar root diameter and length, randomly divided into 5 equal experimental groups.

Effect of reduced post length on the resistance to fracture of crowned, endodontically treated teeth.

Objective: To examine the influence of a reduced post length sealed with a titanium-reinforced composite luting agent on the fracture resistance of crowned endodontically treated teeth with a 2-mm ferrule on healthy tooth structure.

Method And Materials: The study consisted of 60 intact single-rooted premolars with similar root diameters and lengths. Teeth were endodontically treated and randomly divided into 6 experimental groups (n = 10) with various post lengths (5, 8, and 10 mm) and types (ParaPost and Dentatus) of equal diameter.

Resistance to fracture of crowned endodontically treated premolars restored with ceramic and metal post systems.

Objectives: The objective of this study was to assess the resistance to fracture of crowned endodontically treated premolars with varying ceramic and metal post systems under simulated occlusal load.

Method And Materials: The study consisted of 60 extracted intact premolars with similar root diameter and length. Teeth were divided equally into 4 groups (n = 15) and prepared for posts and cast crowns as follows: group 1 = preformed metal post, composite core, and cast crown; group 2 = cast post and core and cast crown; group 3 = zirconia post, composite core, and cast crown; and group 4 = zirconia post and heat-pressed ceramic core and cast crown.

Effect of low intensity laser irradiation on surgically created bony defects in rats.

Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in the total bone area. However, the exact mechanism of cell biostimulation by laser is still unclear.

[Full arch impression techniques utilizing addition type poly vinyl siloxane for fabrication of tooth born fixed partial dentures].

A precise impression is necessary for fabricating an accurately fitting cast restoration. For this purpose, Polyvinyl Siloxane (PVS) impression materials are extremely popular because of their combination of excellent physical properties, handling characteristics and dimensional stability. Its excellent clinical features remain unaffected if simple measures are guarded.

Heat transfer of impression plasters to an implant-bone interface.

Purpose: The purpose of this in vitro study was to measure heat generated at the implant-bone interface caused by exothermic setting reaction of 2 impression plasters.

Materials And Methods: The study consisted of 20 titanium-alloy abutment impressions connected to a titanium-alloy cylindrical implant embedded in an acrylic-resin mandible in a 37 degrees C water bath. There were 2 types of impression plaster used, Snow-White (Kerr, Romulus, MI) and Xantano (Kulzer, Dormagen, Germany).

Chewing side preference as a type of hemispheric laterality.

Chewing side preference is a factor that could effect prosthodontic treatment. The purpose of this study was to determine whether chewing side was another type of hemispheric lateralization comparable with footedness, handedness, eyedness and earedness. Chewing side preference was tested in 189 subjects of whom 84 were partially edentulous, 98 had a full compliment of dental units (81 included implant-supported restoration restoring the missing teeth and 17 with fully intact dentitions), and seven were fully edentulous, restored with complete dentures.

Assessment of the resistance to fracture of endodontically treated molars restored with amalgam.

Statement Of Problem: Controversy exists concerning the preferred type of final restoration of endodontically treated molars regarding their resistance to fracture under occlusal load.

Purpose: The aim of this study was to assess the resistance to fracture of endodontically treated molars with various degrees of tooth structure loss restored with amalgam under simulated occlusal load.

Material And Methods: .

Effect of core stiffness on the in vitro fracture of crowned, endodontically treated teeth.

Statement Of Problem: Dentin and core materials that substitute for missing dentin are dissimilar materials. A core material with a lower elastic modulus may deform more under applied stress and therefore result in reduced stress concentration at the core/dentin junction.

Purpose: This in vitro study examined the effect of core stiffness on the fracture resistance and failure characteristics of a crowned, endodontically treated tooth under simulated occlusal load.

Impression technique for partially edentulous patients.

This article describes an implant impression technique for partially edentulous patients in which impression plaster and irreversible hydrocolloid are used. The technique ensures accuracy, ease of manipulation, and decreased working time.

Effect of wash bulk on the accuracy of polyvinyl siloxane putty-wash impressions.

Variations in the bulk of wash in a putty-wash impression technique can result in dimensional changes proportional to the thickness of the wash material during setting. The purpose of the study was to determine the amount of wash necessary to achieve accurate stone models while using a two-step putty-wash impression technique with polyvinyl siloxane (PVS) impression material. A total of 45 impressions were made of a stainless steel master model, 15 impressions for each wash thickness (1, 2 and 3 mm).

The use of reinforced composite resin cement as compensation for reduced post length.

Statement Of Problem: Cements that yield high retentive values are believed to allow use of shorter posts.

Purpose: This study investigated the use of reinforced composite resin cement as compensation for reduced dowel length.

Material And Methods: The retention values of stainless steel posts (parallel-sided ParaPost and tapered Dentatus in 5-, 8-, and 10-mm lengths) luted with Flexi-Flow titanium-reinforced composite resin and zinc phosphate cements were evaluated.

Stress levels for well-fitting implant superstructures as a function of tightening force levels, tightening sequence, and different operators.

Statement Of Problem: Unfavorable stress distribution and occlusal overload have been reported to result in failures ranging from screw loosening to loss of osseointegration.

Purpose: The purpose of this study was to assess the effect of different tightening forces and sequences, with different operators, on stresses generated on an accurately fitting implant superstructure on multiple working casts made with a splinted impression technique.

Material And Methods: The effects of different tightening forces (10 and 20 Ncm) were assessed with the use of 30 stone casts made from a metal master model with a splinted impression technique.

Accuracy of three polyvinyl siloxane putty-wash impression techniques.

Statement Of Problem: There is much discussion in the dental literature concerning the effect of the impression technique on the accuracy of cast restorations.

Purpose: This study assessed the accuracy of 3 putty-wash impression techniques using the same impression material (polyvinyl siloxane) in a laboratory model.

Material And Methods: The 3 putty-wash impression techniques used were (1) 1-step (putty and wash impression materials used simultaneously); (2) 2-step with 2-mm relief (putty first as a preliminary impression to create 2-mm wash space with prefabricated copings.

Accuracy of implant impression splinted techniques: effect of splinting material.

Three implant impression techniques, using 3 different splinting materials, were assessed for accuracy in a laboratory model that simulated clinical practice. For group A, an autopolymerizing acrylic resin was used to splint transfer copings. In group B, a dual-cure acrylic resin was used, and for group C, plaster, which was also the impression material, was used.

Accuracy of implant impression techniques.

Three impression techniques were assessed for accuracy in a laboratory cast that simulated clinical practice. The first technique used autopolymerizing acrylic resin to splint the transfer copings. The second involved splinting of the transfer copings directly to an acrylic resin custom tray.

Analysis of load transfer and stress distribution by an implant-supported fixed partial denture.

This study simultaneously examined the load transfer and stress distribution by an implant-supported fixed partial denture. A mandibular implant framework with implants connected to the abutments was embedded in a three-dimensional photoelastic model of a mandible. Strain gauges were attached on the superior surface of the framework, and a vertical load of 7.

A modified impression technique for implant-supported restoration.

An impression technique is proposed for construction of implant-borne restorations that uses a modified autopolymerizing resin custom tray to allow splinting of the impression copings directly to the tray. This method eliminates the use of the dental floss-autopolymerizing resin complex, thus decreasing resin distortion and simplifying the clinical procedures.

Biomechanical considerations in restoring endodontically treated teeth.

Various concepts for dental treatment have been established without appropriate documentation, such as restoration of endodontically treated teeth. Some researchers and dentists strongly recommend including a post with the restoration to strengthen the root. Other studies have indicated that posts may substantially weaken the roots and should be avoided.

Effect of post design on resistance to fracture of endodontically treated teeth with complete crowns.

The effect of post design on the fracture resistance of endodontically treated premolars restored with cast crowns was examined in vitro. The experimental model used cast posts and cores to test the effect of post design in a post-core system with identical rigidity. Samples loaded on an Instron testing machine until failure revealed that post design did not influence the fracture resistance of endodontically treated premolars restored with complete cast crowns.

The degree of zinc phosphate cement coverage of complete crown preparations and its effect on crown retention.

This investigation examined the amount of retentive area covered by cement under complete coverage crowns and its effect on retention. Sixty crowns of self-cured acrylic resin were prepared on 60 identical brass dies and were divided into six groups of 10 crowns each according to different cement applications. The results showed that retention was dependent on the amount of retentive area covered by the cement.

The cantilever fixed partial denture--a literature review.

The cantilever fixed partial denture (FPD) is a restoration with one or more abutments at one end and unsupported at the other end. Forces transmitted through the cantilevered pontics can cause tilting and rotational movements of the abutments. In a cross-arch unilateral cantilever FPD, the distal cantilevered unit is subjected to comparatively less force than the contralateral posterior abutment.

Comparative accuracy of implant impression procedures.

In this study, four impression procedures were assessed for accuracy in a laboratory model that simulated clinical practice. The accuracy of stone casts with brass implant analogs was measured against a standard framework. The fit of the framework on the casts was tested by manual and visual judgment and by microscopic measurement.

Restoring teeth following crown lengthening procedures.

Crown lengthening procedures are often necessary to successfully restore teeth that have been mutilated at or below the level of the bone crest. Forced eruption is preferred to surgical removal of supporting alveolar bone, since forced eruption preserves the biologic width, maintains esthetics, and at the same time exposes sound tooth structure for the placement of restorative margins. To properly construct a crown, the minimal distance from the alveolar crest to the coronal extent of sound tooth structure should be 4 mm.

A controlled putty-wash impression technique.

A precise impression is imperative for the construction of an accurately fitting indirect cast restoration. The putty-wash technique is commonly used in making impressions with silicone elastomers. Errors in manipulation may lead to inaccurate impressions.