Technical note: Artificial Resynthesis Technology for the experimental formation of dental microwear textures.

Dental microwear formation on the posterior dentition is largely attributed to an organism's diet. However, some have suggested that dietary and environmental abrasives contribute more to the formation process than food, calling into question the applicability of dental microwear to the reconstruction of diet in the fossil record. Creating microwear under controlled conditions would benefit this debate, but requires accurately replicating the oral environment.

Use of a continual sweep motion to compare air polishing devices, powders and exposure time on unexposed root cementum.

Low abrasive air polishing powders are a viable method for subgingival biofilm removal. This in vitro study evaluated the effects of air polishing using a standard tip on cementum following clinically recommended protocols. Forty-eight teeth were randomly divided into eight groups with six teeth per group.

Relationships between tissue properties and operational parameters of a dental handpiece during simulated cavity preparation.

A preliminary study was conducted on the development of an intelligent dental handpiece with functionality to detect subtle changes in mechanical properties of tooth tissue during milling. Such equipment would be able to adopt changes in cutting parameters and make real-time measurements to avoid tooth tissue damage caused by overexertion and overextension of the cutting tool. A modified dental handpiece, instrumented with strain gauges, microphone, displacement sensor, and air pressure sensor, was mounted to a linear movement table and used to mill three to four cavities in >50 bovine teeth.

Wear of a dental composite in an artificial oral environment: A clinical correlation.

The study objective was to correlate wear between an in vitro method for simulating wear and in vivo wear of a posterior dental composite. Ten subjects (12 restorations) were selected from a five-year clinical study (University of North Carolina, School of Dentistry) that assessed wear of SureFil composite (Caulk, Dentsply). Subject casts were digitized and changes in volume and mean depth with time were calculated from the 3D digital models for contact and contact-free wear.

Quantitative analysis of tooth surface loss associated with gastroesophageal reflux disease: a longitudinal clinical study.

Background: Acid regurgitation resulting from gastroesophageal reflux disease (GERD) causes dissolution of tooth structure. The authors conducted a longitudinal clinical study to measure tooth surface loss associated with GERD.

Methods: The authors made replicas of dental impressions obtained from 12 participants with GERD and six control participants at baseline and six months.

Can hygroscopic expansion compensate polymerization shrinkage? Part I. Deformation of restored teeth.

Objective: Restorative materials exhibit contraction and expansion due to polymerization and water absorption. Each process deforms and stresses a restored tooth structure in opposite direction. This study evaluated the tooth deformations during these competing processes.

Calcium phosphate formation in gelatin matrix using free ion precursors of Ca2+ and phosphate ions.

Objectives: Hydroxyapatite (HAp)/gelatin (GEL) nanocomposite has been developed as a bone substitute. The nanocomposite formation in the GEL matrix is greatly affected by the reaction between Ca(2+) and phosphate ions. The mineralization of GEL macromolecules was investigated through a co-precipitation of calcium phosphates (Ca-P) by using free ions of Ca(2+) and phosphate ions, Pi.

Predicting first molar width using virtual models of dental arches.

In dentistry, large regions of dentition often are restored with minimal information about the original anatomy. The ability to predict missing anatomy from existing anatomy would aid such restorations. This study investigated the relationship between first molar mesial-distal width and arch shape using newly defined reference points and three-dimensional (3D) digital methods.

Accuracy of two impression techniques with angulated implants.

Statement Of Problem: Accurate recording of implant locations is required so that definitive restorations are properly supported and do not place additional stress on the implants. Angulated implants may result in inaccurate impressions, and the impression technique may affect the accuracy of the definitive cast.

Purpose: The purpose of this study was to determine the effect the combined interaction of impression technique, implant angulation, and implant number has on the accuracy of implant definitive casts.

Intra-oral restorative materials wear: rethinking the current approaches: how to measure wear.

Objective: To determine what wear parameter(s) have clinical relevance and what factors are important for accurate measurement of these parameters in vivo and in vitro.

Method: Describe biomechanical factors affecting mastication and the mechanics of wear. Investigate how they impact the wear of teeth and restorative materials.

Comparison of the finite helical axis and the rectangular coordinate system in representing orthodontic tooth movement.

In orthodontics, tooth movement is typically described using the rectangular coordinate system (XYZ); however, this system has several disadvantages when performing biomechanical analyses. An alternative method is the finite helical axis (FHA) system, which describes movement as a rotation about and a translation along a single axis located in space. The purpose of this study was to examine differences between the FHA and the XYZ systems in analyzing orthodontic tooth movement.

Residual shrinkage stress distributions in molars after composite restoration.

Objective: Experimental measurements on various restoration configurations have shown that restored teeth deform under the influence of polymerization shrinkage, but actual residual stresses could not be determined. The purpose of this study was to calculate and validate shrinkage stresses associated with the reported tooth deformations.

Methods: Three different restoration configurations were applied in a finite element model of a molar.

Tooth deformation patterns in molars after composite restoration.

Objective: Residual stresses from polymerization shrinkage in composite restorations deform a tooth. This may cause debonding, enamel crack propagation, and post-operative sensitivity. Deformation due to shrinkage has been measured previously at a few discrete points.

Clinical evaluation of a new resilient denture liner. Part 1: Compliance and color evaluation.

Purpose: A new experimental resilient denture liner (MPDS-SL; Lai Laboratories, Burnsville, MN) and Molloplast-B (Buffalo Dental Manufacturing, Syosset, NY) were clinically evaluated for compliance and color change over a 1-year period.

Materials And Methods: In this crossover study, each of 20 patients had 2 dentures fabricated with long-term, silicone-based resilient liners, 1 denture with Molloplast-B and the other with MPDS-SL. Each denture was used for 6 months, during which time each patient kept a journal detailing his or her use and cleaning regimen.

Comparing maximum intercuspal contacts of virtual dental patients and mounted dental casts.

Statement Of Problem: Quantitative measures of occlusal contacts are of paramount importance in the study of chewing dysfunction. A tool is needed to identify and quantify occlusal parameters without occlusal interference caused by the technique of analysis.

Purpose: This laboratory simulation study compared occlusal contacts constructed from 3-dimensional images of dental casts and interocclusal records with contacts found by use of conventional methods.

An intra-oral hydraulic system for controlled loading of dental implants.

This study reports a method for controlling loads on an in vivo dental implant and its application for the investigation of early loading versus delayed loading of dental implants. The method was developed for the purpose of studying an ongoing hypothesis that amounts to bone loss around dental implants are related to mechanical-mediated adaptation of the alveolar bone. Using a customized intra-oral hydraulic system, the daily loading over a dental implant has been completed and recorded for six Sinclair swine.

Factors affecting enamel and ceramic wear: a literature review.

Enamel wear by ceramics may adversely affect maintenance of the vertical dimension of occlusion and can increase the potential for thermal sensitivity. In this article, factors related to the abrasion of enamel by dental ceramics are critically reviewed. Concepts of physical, microstructural, chemical, and surface characteristics of dental ceramics on wear are presented based on research published since 1950.

Laser digitization of casts to determine the effect of tray selection and cast formation technique on accuracy.

Unlabelled: STATEMENT OF PROBLEM; Several studies have attempted to determine the ideal combination of dental materials and laboratory techniques to produce the most accurate dental cast. Most have made use of 2-dimensional manual measuring devices, which neglect to account for the dimensional changes that exist along a 3-dimensional surface.

Purpose: The purpose of this study was to determine the effect of impression tray selection and cast formation techniques on the dimensional change of a dental cast with the use of new, 3-dimensional optical digitizing technology.