Finite Element Analysis Generates an Increasing Interest in Dental Research: A Bibliometric Study.

PURPOSE: The purpose was to provide a longitudinal overview of published studies that use finite element analysis in dental research, by using the SCI-expanded database of Web of Science(®) (Thomson Reuters). MATERIAL AND METHODS: Eighty publications from 1999-2000 and 473 from 2009-2010 were retrieved. This literature grew faster than the overall dental literature. The number of publishing countries doubled. The main journals were American or English, and dealt with implantology. For the top 10 journals publishing dental finite element papers, the mean impact factor increased by 75% during the decade. RESULTS: Finite elements generate an increasing interest from dental authors and publishers worldwide.

On Comparing Two Different Tray-Holding Techniques for Edentulous Maxillary Impressions.

PURPOSE: This study compared tissue three-dimensional (3D) displacements during the material setting phase of two maxillary impression tray-holding techniques: clinician manual pressure and patient occlusal pressure. MATERIALS AND METHODS: The resultant two maxillary casts for each of 10 edentulous patients were compared using an optical 3D measurement system. RESULTS: The junction between the hard and soft palates acted like a rotation center during impression making. The vertical displacements were significantly lower and posteriorly set when the impression was taken with the patient's occlusion, in contrast to being located at the anterior two-thirds during the manual impression technique. CONCLUSION: Use of patient's occlusion as a tray-holding technique may be preferred during the material setting phase of maxillary impressions.

Craniofacial morphometric analysis of individuals with X-linked hypohidrotic ectodermal dysplasia.

Hypohidrotic ectodermal dysplasia (HED) is the most prevalent type of ectodermal dysplasia (ED). ED is an umbrella term for a group of syndromes characterized by missing or malformed ectodermal structures, including skin, hair, sweat glands, and teeth. The X-linked recessive (XL), autosomal recessive (AR), and autosomal dominant (AD) types of HED are caused by mutations in the genes encoding ectodysplasin (EDA1), EDA receptor (EDAR), or EDAR-associated death domain (EDARADD). Patients with HED have a distinctive facial appearance, yet a quantitative analysis of the HED craniofacial phenotype using advanced three-dimensional (3D) technologies has not been reported. In this study, we characterized craniofacial morphology in subjects with X-linked hypohidrotic ectodermal dysplasia (XLHED) by use of 3D imaging and geometric morphometrics (GM), a technique that uses defined landmarks to quantify size and shape in complex craniofacial morphologies. We found that the XLHED craniofacial phenotype differed significantly from controls. Patients had a smaller and shorter face with a proportionally longer chin and midface, prominent midfacial hypoplasia, a more protrusive chin and mandible, a narrower and more pointed nose, shorter philtrum, a narrower mouth, and a fuller and more rounded lower lip. Our findings refine the phenotype of XLHED and may be useful both for clinical diagnosis of XLHED and to extend understanding of the role of EDA in craniofacial development.

On the cutting edge of organ renewal: Identification, regulation, and evolution of incisor stem cells.

The rodent incisor is one of a number of organs that grow continuously throughout the life of an animal. Continuous growth of the incisor arose as an evolutionary adaptation to compensate for abrasion at the distal end of the tooth. The sustained turnover of cells that deposit the mineralized dental tissues is made possible by epithelial and mesenchymal stem cells residing at the proximal end of the incisor. A complex network of signaling pathways and transcription factors regulates the formation, maintenance, and differentiation of these stem cells during development and throughout adulthood. Research over the past 15 years has led to significant progress in our understanding of this network, which includes FGF, BMP, Notch, and Hh signaling, as well as cell adhesion molecules and micro-RNAs. This review surveys key historical experiments that laid the foundation of the field and discusses more recent findings that definitively identified the stem cell population, elucidated the regulatory network, and demonstrated possible genetic mechanisms for the evolution of continuously growing teeth.