The Effect of Contamination of Implant Screws on Reverse Torque.

Purpose: To determine if contamination of abutment screws with titanium nanoparticles affects the preload by measuring the reverse torque after multiple cycles of screw closing-opening.

Materials And Methods: The study included 30 internal hex implants, titanium abutments, and titanium abutment screws. Fifteen abutment screws were contaminated with 60- to 80-nm titanium nanoparticles (contamination group), and the remaining 15 screws did not receive titanium nanoparticle contamination (noncontamination group).

Contact angle of unset elastomeric impression materials.

Statement Of Problem: Some elastomeric impression materials are hydrophobic, and it is often necessary to take definitive impressions of teeth coated with some saliva. New hydrophilic materials have been developed.

Purpose: The purpose of this in vitro study was to compare contact angles of water and saliva on 7 unset elastomeric impression materials at 5 time points from the start of mixing.

Influence of implant angulation on the fracture resistance of zirconia abutments.

Purpose: To investigate the effects of abutment design to correct for implant angulation and aging on the fracture resistance of zirconia abutments. Greater understanding of the fracture strength of the zirconia abutments under various clinical conditions may lead to improvement of clinical protocols and possibly limit potential failures of implant prosthetics.

Materials And Methods: Test specimens consisted of an implant-zirconia abutment-zirconia crown assembly with implant apex positioned at 0°, 20° to the facial (20F), and 20° to the lingual (20L) with respect to a constant crown contour.

Comparison of pulp stump wounds created by profile rotary root canal instruments and small-diameter fine diamond burs.

Introduction: The aim of this investigation was to evaluate and compare the pulp stump wounds created by the following root canal instruments: ProFile rotary files and small-diameter fine diamond burs.

Methods: Extracted mandibular premolars from adult patients with vital pulps and fully formed root canals were collected and stored in formalin. Within 48 hours of extraction, the periapical tissue was fixated to the root with a double coating of ethyl cyanoacrylate, and the pulp chambers were accessed with a #4 round carbide bur and high-speed handpiece in a traditional fashion.

Effect of Luting Agents on Retention of Dental Implant-Supported Prostheses.

To evaluate the retentive strength of 7 different luting agents in cement-retained implant abutment/analog assemblies. Fifty-six externally hexed dental implant abutment/analog assemblies and cast superstructures were divided randomly into 7 groups for cementation with each of the 7 luting agents. Five definitive cements tested were zinc phosphate cement, All-Bond 2, Maxcem, RelyX Luting cement, HY-Bond, and two provisional cements, ImProv and Premier.

Influence of surface treatment of yttrium-stabilized tetragonal zirconium oxides and cement type on crown retention after artificial aging.

Statement Of Problem: Information about the influence of zirconia crown surface treatment and cement type on the retention of zirconia crowns is limited. It is unclear whether zirconia crowns require surface treatment to enhance their retention.

Purpose: The purpose of this in vitro study was to evaluate the effect of surface treatment on the retention of zirconia crowns cemented with 3 different adhesive resin cements after artificial aging.

The wear of polished and glazed zirconia against enamel.

Statement Of Problem: The wear of tooth structure opposing anatomically contoured zirconia crowns requires further investigation.

Purpose: The purpose of this in vitro study was to measure the roughness and wear of polished, glazed, and polished then reglazed zirconia against human enamel antagonists and compare the measurements to those of veneering porcelain and natural enamel.

Material And Methods: Zirconia specimens were divided into polished, glazed, and polished then reglazed groups (n=8).

Fracture resistance and marginal discrepancy of porcelain laminate veneers influenced by preparation design and restorative material in vitro.

Objectives: The purpose of this investigation is to evaluate marginal discrepancy and fracture resistance of two veneering materials using two preparation designs.

Methods: Two veneer preparation designs (full and traditional) were restored with leucite-reinforced ceramic (ProCAD, Ivoclar Vivadent, Amherst, NY) milled by CAD/CAM (Cerec 3D milling system, Serona Dental Systems), and conventional sintered feldspathic porcelain (Noritake Super Porcelain EX3, Noritake Dental Supply Co). Forty-eight specimens were analysed with a sample size of n=12 per group.

Gloss and surface roughness produced by polishing kits on resin composites.

Purpose: To compare in vitro the surface roughness (Ra) and gloss (G) produced by three conventional and one experimental polishing kits on four resin composites.

Methods: 24 discs were prepared (d = 12 mm, t = 4 mm) for each resin composite: Filtek Supreme Plus Body/A2 (FSB), Yellow Translucent (FST), Heliomolar/A2 (HM), and EsthetX/A2 (EX) following the manufacturers' instructions. They were finished with 320 grit silicon carbide paper for 80 seconds each.

A preliminary survey of impression trays used in the fabrication of fixed indirect restorations.

Purpose: A variety of impression trays are used in the fabrication of fixed indirect restorations. Impressions used in the construction of fixed indirect restorations were examined for tray type, manner of use, and overall impression quality.

Materials And Methods: A commercial dental laboratory provided 1403 impressions used to fabricate fixed indirect restorations during a 3-month period.

Acid-etch interval and shear bond strength of Er,Cr:YSGG laser-prepared enamel and dentin.

The formation of a superficial layer of tiny flakes has been observed on teeth prepared by Erbium lasers. It has been suggested that removing this layer (mechanically or chemically) may increase the bond strength of the resin composite. The purpose of this study is to evaluate the effect of various etching times on bond strength of resin composite to enamel and dentin prepared by Er,Cr:YSGG laser.

The effect of etching technique on the retention of adhesively cemented prefabricated dowels.

Purpose: To determine if etching technique influences the bond strength of resin cement to root canal dentin.

Materials And Methods: Fifty-five extracted teeth were endodontically treated, dowel space prepared, and divided into five groups. Each group was treated with different etchant consistencies: acid gel, semi-gel, low-viscosity gel, liquid, and a self-etching primer.

Biomechanical response of implant systems placed in the maxillary posterior region under various conditions of angulation, bone density, and loading.

Purpose: The aim of this study was to determine the relative contribution of changes in implant system, position, bone type, and loading condition on the biomechanical response of a single-unit implant-supported restoration using nonlinear 3-dimensional finite element analysis (3D FEA).

Materials And Methods: FEA models of a single-unit (crown) restoration supported by the Frialit-2 implant and MH-6 abutment or the Straumann standard implant with the Straumann solid abutment were used. Each system was analyzed by FEA with both straight and 20-degree angled abutments.

Patient responses to dental implant-retained mandibular overdenture therapy: a 6-year clinical study.

Background: The purpose of this study was to record subjective patient experiences with respect to the surgical placement of dental implants and the functioning of mandibular implant-retained overdentures versus conventional dentures.

Methods: Completely edentulous patients (n = 56) unable to wear a conventional mandibular complete denture were each treated with 4 one-stage titanium plasma sprayed or Sandblasted Large-grit Acid-etched (SLA) screw implants and overdentures retained by a cast bar with extracoronal attachments. Fifty-six patients were subsequently clinically evaluated over a period of up to 6 years.

Comparison of 7 luting protocols and their effect on the retention and marginal leakage of a cement-retained dental implant restoration.

Purpose: To determine the cement bond strength and marginal leakage of castings cemented to implant abutments.

Materials And Methods: Fifty-six titanium abutments and castings were divided into 7 groups (n=8), 1 for each cement. Castings were cemented to abutments using 1 of 3 resin-based cements (RES, RES-B, and RES-B-P), a resin-modified glass ionomer (GI), a polycarboxylate cement (PCB), an acrylic urethane cement (UDM), or a zinc phosphate cement (ZP).

Hardness and wear resistance of two resin composites cured with equivalent radiant exposure from a low irradiance LED and QTH light-curing units.

Purpose: To measure and compare three-body wear and Vickers hardness at depths of 0 mm and 2 mm in two composite resin materials cured with either a low irradiance light emitting diode (LED) or a quartz tungsten halogen (QTH) light-curing unit (LCU) in which exposure duration with the LED was increased to deliver equivalent radiant exposure in the 450-490 nm wavelength range.

Methods: The VIP QTH and Freelight LED LCU's were obtained and the emission spectrum of each was determined using a Spectra Pro 750 spectrograph. Irradiance in the 450-490 nm range for each LCU was determined by calculating the area under the spectral curve.