Peter De Coster

The natural history, including orofacial features of three patients with Ehlers-Danlos syndrome, dermatosparaxis type (EDS type VIIC).

Ehlers–Danlos syndrome (EDS) dermatosparaxis type (type VIIC) and the related disease of cattle dermatosparaxis, are recessively inherited connective tissue disorders, caused by a deficient activity of procollagen I N‐proteinase, the enzyme that excises the N‐terminal propeptide in procollagen type I, type II, and type III. Although well documented in cattle, to date only seven human cases have been recorded, most of them aged under 2 years. We document the natural history of three patients with EDS dermatosparaxis type, two of whom have been reported before the age of 2 years, and one new patient. The phenotype of the patients, and especially the facial resemblance, is striking, making this a clinically recognizable condition. The most consistent anomalies during the first years of life are premature rupture of the membranes, extreme skin fragility and easy bruising, large fontanels, blue sclerae, puffy eyelids, micrognathia, umbilical hernia, and short fingers. Joint hypermobility becomes more important with age. The children are at risk for rupture of internal organs due to soft tissue fragility, as is illustrated by different internal events in two of the three patients described here. Orofacial features include micrognathia, a frontal open bite, and gingival hyperplasia with varying degrees of hyperkeratosis. The deciduous dentition shows abnormal morphology of the molars, obliteration of the tooth pulp, and severe enamel attrition. The permanent dentition shows agenesis and microdontia of several teeth. Tooth discoloration, dysplastic roots, and tooth pulp obliteration are present in a restricted number of permanent teeth.

Craniofacial structure in Marfan syndrome: A cephalometric study†

Marfan syndrome (MFS) is a connective tissue disorder with autosomal dominant inheritance. Mutations in the FBN1 gene cause deficient processing of fibrillin‐1, the main constituent of extracellular microfibrils, affecting tissues displaying elastic properties. Clinical manifestations are widespread and involve the skeletal, ocular, cardiovascular and pulmonary systems, skin and integumentum, and dura. A highly arched palate and retrognathia have been assigned to the symptoms with minor diagnostic specificity, although epidemiological data on prevalence are lacking yet. Twenty‐six patients with MFS (n = 26) were studied for craniofacial characteristics using cephalometric measurements on lateral cranial radiographs. The purposes of this study were (1) to compare cephalometric variables of MFS group with age‐ and sex‐matched population norms, and (2) to assess differences in palatal vault dimensions among adult MFS (n = 17) and matched controls (n = 32) by means of cephalometric measurements. Significant differences with population norms were found in the structures of the cranial base, the maxillary complex, the mandible body, and the relations of the jaws with respect to the cranial base and to each other. Palatal height and palatal length were significantly larger in MFS, and were significantly correlated to each other and to the height of the maxillo‐alveolar processus. The present data disprove in part previously reported findings, possibly due to biased patient selection in these studies or demographic differences. However, a strong correlation was found between maxillary/mandibular retrognathia, long face, highly arched palate, and MFS. A combination of both intrinsic genetic factors and environmental factors is suggested as a possible explanation for specific morphogenetic aspects of the craniofacial complex in MFS.

Gene Expression Profiling and Molecular Signaling of Dental Pulp Cells in Response to Tricalcium Silicate Cements: A Systematic Review

INTRODUCTION Signaling molecules and responding dental pulp stem cells are the 2 main control keys of dentin regeneration/dentinogenesis. The aim of this study was to present a systematic review investigating the gene expression of various dental pulp cells in response to different variants of tricalcium silicate cements. METHODS A systematic search of the literature was performed by 2 independent reviewers followed by article selection and data extraction. Studies analyzing all sorts of dental pulp cells (DPCs) and any variant of tricalcium silicate cement either as the experimental or as the control group were included. RESULTS A total of 39 articles were included in the review. Among the included studies, ProRoot MTA (Dentsply, Tulsa Dental, OK) was the most commonly used tricalcium silicate cement variant. The extracellular signal regulated kinase/mitogen-activated protein kinase pathway was the most commonly activated pathway to be identified, and similarly, dentin sialophosphoprotein osteocalcin dentin matrix acidic phosphoprotein 1, alkaline phosphatase, bone sialoprotein, osteopontin, type I collagen, and Runx2 were the most commonly expressed genes in that order of frequency. CONCLUSIONS Biodentine (Septodont Ltd, Saint Maur des Faussés, France), Bioaggregate (Innovative Bioceramix, Vancouver, BC, Canada), and mineral trioxide aggregate stimulate the osteogenic/odontogenic capacity of DPCs by proliferation, angiogenesis, and biomineralization through the activation of the extracellular signal regulated kinase ½, nuclear factor E2 related factor 2, p38, c-Jun N-terminal kinase mitogen-activated protein kinase, p42/p44 mitogen-activated protein kinase, nuclear factor kappa B, and fibroblast growth factor receptor pathways. When DPCs are placed into direct contact with tricalcium silicate cements, they show higher levels of gene activation, which in turn could translate into more effective pulpal repair and faster and more predictable formation of reparative dentin.

Laser-assisted pulpotomy in primary teeth: a systematic review

OBJECTIVE The purpose of this systematic review was to identify high-quality articles comparing laser with conventional pulpotomy procedures, and to assess whether laser treatment may offer an appreciable benefit over conventional approaches. METHODS A systematic search was implemented for MEDLINE, WEB of SCIENCE and Cochranes CENTRAL databases (1980-2012) to identify eligible studies. Two reviewers independently assessed the methodological quality of the articles (Κ = 0.89) using specific study design-related quality assessment forms (Dutch Cochrane Collaboration). RESULTS Seven articles met the inclusion criteria, of which five randomized control trials (RCT) and two case series (CS), involving Nd:YAG, Er:YAG, CO₂ and 632/980 nm diode lasers. Although heterogeneity between pulpotomy studies was high, odds ratios (OR) were generally <1, indicating that laser is less successful than conventional pulpotomy techniques. CONCLUSION Given the paucity and high heterogeneity of high-quality articles, general recommendations for the clinical use of laser in pulpotomy in primary teeth can yet not be formulated.

Insight in the Chemistry of Laser-Activated Dental Bleaching

The use of optical radiation for the activation of bleaching products has not yet been completely elucidated. Laser light is suggested to enhance the oxidizing effect of hydrogen peroxide. Different methods of enhancing hydrogen peroxide based bleaching are possible. They can be classified into six groups: alkaline pH environment, thermal enhancement and photothermal effect, photooxidation effect and direct photobleaching, photolysis effect and photodissociation, Fenton reaction and photocatalysis, and photodynamic effect.

Characterization of a novel mutation in PAX9 gene in a family with non-syndromic dental agenesis

BACKGROUND Dental agenesis is the most common developmental anomaly in man and may present either as an isolated trait or as part of a syndrome, such as ectodermal dysplasia. Until now, the underlying molecular pathogenic mechanisms responsible for dental agenesis are still largely unknown. Several genetic and molecular studies have demonstrated that at least 300 genes are involved in tooth formation and development, coding for specific transcriptional factors, receptors or growth factors that are expressed at specific developmental stages. Dental agenesis in this respect is believed to result from altered expression of one or more of these factors during initiation and early morphogenesis of the tooth germ, and the first actors identified were MSX1 and PAX9. DESIGN In this study, we focalized on a Tunisian family with a non-syndromic autosomal dominant form of tooth agenesis. In order to screen for the eventual genetic cause of dental agenesis in this family we sequenced 4 genes; PAX9, WNT10A, MSX1 and AXIN2 using Sanger sequencing. RESULTS Direct Screening analysis of PAX9 gene, revealed a novel mutation p.Asp200Serfs*13. It consists of a duplication of 5 basepairs leading to a codon stop 13 position downstream. This novel mutation was found in all affected family members. CONCLUSIONS In this report, we present the first genetic study of a Tunisian family with a non-syndromic autosomal dominant form of tooth agenesis, in which we identified in PAX9 gene a novel mutation. It most likely results in nonsense mediated RNA decay and haploinsifficiency that reduce the transactivation capacity of PAX9.

Laser Teeth Bleaching: Evaluation of Eventual Side Effects on Enamel and the Pulp and the Efficiency In Vitro and In Vivo

Light and heat increase the reactivity of hydrogen peroxide. There is no evidence that light activation (power bleaching with high-intensity light) results in a more effective bleaching with a longer lasting effect with high concentrated hydrogen peroxide bleaching gels. Laser light differs from conventional light as it requires a laser-target interaction. The interaction takes place in the first instance in the bleaching gel. The second interaction has to be induced in the tooth, more specifically in the dentine. There is evidence that interaction exists with the bleaching gel: photothermal, photocatalytical, and photochemical interactions are described. The reactivity of the gel is increased by adding photocatalyst of photosensitizers. Direct and effective photobleaching, that is, a direct interaction with the colour molecules in the dentine, however, is only possible with the argon (488 and 415 nm) and KTP laser (532 nm). A number of risks have been described such as heat generation. Nd:YAG and especially high power diode lasers present a risk with intrapulpal temperature elevation up to 22°C. Hypersensitivity is regularly encountered, being it of temporary occurrence except for a number of diode wavelengths and the Nd:YAG. The tooth surface remains intact after laser bleaching. At present, KTP laser is the most efficient dental bleaching wavelength.

An experimental study on periodontal regeneration after subcutaneous transplantation of rat molar with and without cryopreservation: an in vivo study.

This study analysed the effects of cryopreservation on periodontal regeneration of autotransplanted rat molars. First and second maxillary molars (n=92) of 24 four-week-old Wistar rats were gently extracted and autotransplanted into the abdominal tissue immediately (control group n=44) or after cryopreservation in liquid nitrogen for 7 days (experimental group n=48). At 1, 2, 4 and 10 weeks after transplantation, the transplanted molars were excised and regeneration of the periodontal tissues was analysed on histological sections stained with routine H&E and Goldner method. Different tissue responses were scored on a tooth basis: inflammation, regeneration of the periodontal ligament, resorption/apposition of cementum, and alveolar bone formation. Sixty-two teeth were available for histological evaluation, including 30 experimental and 32 control samples. One week after transplantation, both control and test teeth were surrounded by granulation tissue and some areas of root resorption could be seen. After 2 weeks, signs of regeneration of the periodontal ligament, cementum apposition, and new bone formation roughly coincided in both groups, however markedly retarded in the experimental group. After 4 weeks, regeneration progressed equally in both groups, presenting fewer areas of cementum apposition in experimental samples. Finally, 10 weeks after baseline transplantation, no significant differences between both groups could be observed. Cryopreservation followed by autotransplantation of extracted teeth in rats appears to have minimal detrimental effects on regeneration of periodontal tissues after integration periods of 1-10 weeks. However, the present findings indicated that the regeneration process in general is retarded for cryopreserved teeth, as compared to their immediately transplanted homologues.

Genetic study of non-syndromic tooth agenesis through the screening of paired box 9, msh homeobox 1, axin 2, and Wnt family member 10A genes: a case-series

Non-syndromic tooth agenesis (NSTA) is the most common developmental anomaly in humans. Several studies have been conducted on dental agenesis and numerous genes have been identified. However, the pathogenic mechanisms responsible for NSTA are not clearly understood. We studied a group of 28 patients with sporadic NSTA and nine patients with a family history of tooth agenesis. We focused on four genes - paired box 9 (PAX9), Wnt family member 10A (WNT10A), msh homeobox 1 (MSX1), and axin 2 (AXIN2) - using direct Sanger sequencing of the exons and intron-exon boundaries. The most prevalent variants identified in PAX9 and AXIN2 genes were analyzed using the chi-square test. The sequencing results revealed a number of variants in the AXIN2 gene, including one novel missense mutation in one patient with agenesis of a single second premolar. We also identified one variant in the AXIN2 gene as being a putative risk factor for tooth agenesis. Only one missense mutation was identified in the WNT10A gene and this mutation was found in two patients. Interestingly, WNT10A is reported as the most prevalent gene mutated in the European population with NSTA.