Evaluation of distances between the mandibular teeth and the alveolar process in Brazilians with normal occlusion

Introduction: The aims of this study were to evaluate the distances between the mandibular permanent teeth and the alveolar process in Brazilians with normal occlusion and to compare them with normal American values. Methods: We used 59 mandibular casts from untreated subjects who had permanent dentition and the 6 keys to normal occlusion. A computer program was used to calculate the distances between the dental reference points and the alveolar process for each tooth. The mean values were then compared to the normal values by applying the Student t test at a significance level of 0.05. Results: The results showed a progressive increase of these distances from the anterior region (incisors) to the posterior region (molars), from 0.00 to 2.49 mm. All measurements had statistically significant differences from the American sample, except for the values for canines and first premolars. Conclusions: Brazilians with normal occlusion have more lingual crown positions for the incisors, second premolars, and molars compared with Americans with normal occlusion. Although these findings were statistically significant, they are unlikely to be clinically significant. (Am J Orthod Dentofacial Orthop 2010; 137: 308.e1-308.e4)

Evolution of Teeth and Quadrate in Non-avian Theropoda (Dinosauria: Saurischia), with the Description of Torvosaurus Remains from Portugal

Theropods form a highly successful and morphologically diversified group of dinosaurs that gave rise to birds. They include most, if not all, carnivorous dinosaurs, yet many theropod clades were secondarily adapted to piscivory, omnivory and herbivory, and theropods show a large array of skull and dentition morphologies. This work aims to investigate aspects of the evolution of theropod dinosaurs by analyzing in detail both the anatomy and ontogeny of teeth and quadrates in non-avian theropods, and by studying embryonic and adult material of a new species of theropod. A standardized list of terms and notations for each anatomical entity of the tooth, quadrate, and maxilla is here proposed with the goal of facilitating descriptions of these important cranial and dental elements. The distribution of thirty dental characters among 113 theropod taxa is investigated, and a list of diagnostic dental characters is proposed. As an example, four isolated theropod teeth from the Lourinhã Formation (Kimmeridgian‒Tithonian) of Portugal are described and identified based on a cladistic analysis performed on a data matrix of 141 dentition-based characters coded in 60 taxa. Two shed teeth are referred to an abelisaurid, providing the first record of Abelisauridae in the Jurassic of Laurasia and the one of the oldest records of this clade in the world, suggesting a possible radiation of Abelisauridae in Europe well before the Upper Cretaceous. The consensus tree resulting from this phylogenetic analysis, the most extensive on theropod teeth, indicates that theropod teeth provide reliable data for identification at approximately family level, and this method will help identifying theropod teeth with more confidence. A detailed description of the dentition of Megalosauridae is also provided, and a discriminant analysis performed on a dataset of numerical data collected on the teeth of 62 theropod taxa reveals that megalosaurid teeth are hardly distinguishable from other theropod clades with ziphodont dentition. This study highlights the importance of detailing anatomical descriptions and providing additional morphometric data on teeth with the purpose of helping to identify isolated theropod teeth. In order to evaluate the phylogenetic potential and investigate the evolutionary transformations of the quadrate, a phylogenetic morphometric analysis as well as a cladistic analysis using 98 discrete quadrate related characters were conducted. The quadrate morphology by its own provides a wealth of data with strong phylogenetic signal, and the phylogenetic morphometric analysis reveals two main morphotypes of the mandibular articulation of the quadrate linked to function. As an example, six isolated quadrates from the Kem Kem beds (Cenomanian) of Morocco are determined to be from juvenile and adult individuals of Spinosaurinae based on phylogenetic, morphometric, and phylogenetic morphometric analyses. Morphofunctional analysis of the spinosaurid mandibular articulation has shown that the posterior parts of the two mandibular rami displaced laterally when the jaw was depressed due to a mediolaterally oriented intercondylar sulcus of the quadrate. Such lateral movement of the mandibular ramus was possible due to a movable mandibular symphysis in spinosaurids, allowing the pharynx to be widened. A new species of theropod from the Lourinhã Formation of Portugal, Torvosaurus gurneyi, is erected based on a right maxilla and an incomplete caudal centrum. This taxon supports the mechanism of vicariance that occurred in the Iberian Meseta during the Late Jurassic when the proto-Atlantic was already well formed. A theropod clutch containing several crushed eggs and embryonic material is also assigned to this new species of Torvosaurus. Investigation on the maxilla ontogeny in basal tetanurans reveals that crown denticles, elongation of the anterior ramus, and fusion of interdental plates appear at a posthatchling stage. On the other hand, maxillary pneumaticity is already present at an embryonic stage in non-avian theropods.

Rigid Rod Polymer Fillers in Acrylic Denture and Dental Adhesive Resin Systems

Polymeric materials have been used in dental applications for decades. Adhesion of polymeric materials to each other and to the tooth substrate is essential to their successful use. The aim of this series of studies was two-folded. First, to improve adhesion of poly(paraphenylene) based rigid rod polymer (RRP) to other dental polymers, and secondly, to evaluate the usability of a new dentin primer system based on RRP fillers. Poly(paraphenylene) based RRP would be a tempting material for dental applications because of its good mechanical properties. To be used in dental applications, reliable adhesion between RRP and other dental polymers is required. In this series of studies, the adhesion of RRP to denture base polymer and the mechanical properties of RRP-denture base polymer-material combination were evaluated. Also adhesion of BisGMA-TEGDMA-resin to RRP was determined. Different surface treatments were tested to improve the adhesion of BisGMA-TEGDMA-resin to RRP. Results were based on three-point bending testing, Vickers surface hardness test and scanning electron microscope analysis (SEM), which showed that no reliable adhesion between RRP and denture base polymer was formed. Addition of RRP filler to denture base polymer increased surface hardness and flexural modulus but flexural strength decreased. Results from the shear bond strength test and SEM revealed that adhesion between resin and RRP was possible to improve by surface treatment with dichloromethane (DCM) based primer and a new kind of adhesive surface can be designed. The current dentin bonding agents have good immediate bond strength, but in long term the bond strength may decrease due to the detrimental effect of water and perhaps by matrix metalloproteinases. This leads to problems in longevity of restorations. Current bonding agents use organic monomers. In this series of studies, RRP filled dentin primer was tested in order to decrease the water sorption of the monomer system of the primers. The properties of new dentin primer system were evaluated in vitro by comparing it to commercial etch and rinse adhesive system. The results from the contact angle measurements and SEM showed that experimental primer with RRP reinforcement provided similar resin infiltration to dentin collagen and formed the resin-dentin interface as the control primer. Microtensile bond strength test and SEM revealed that in short term water storing, RRP increased bond strength and primer with BMEP-monomer (bis[2-(methacryloyloxy)-ethyl]phosphate) and high solvent concentration provided comparable bonding properties to the commercial control primers. In long term water storing, the high solvent-monomer concentration of the experimental primers decreased bond strength. However, in low solvent-monomer concentration groups, the long-term water storing did not decrease the bond strength despite the existence of hydrophilic monomers which were used in the system. These studies demonstrated that new dentin primer system reached the mechanical properties of current traditional etch and rinse adhesive system in short time water storing. Improved properties can be achieved by further modifications of the monomer system. Studies of the adhesion of RRP to other polymers suggest that adhesion between RRP and other dental polymers is possible to obtain by certain surface treatments.

Anatomical and histological characteristics of teeth in agouti (Dasyprocta prymnolopha Wagler, 1831)

The agouti species Dasyprocta prymnolopha (D. prymnolopha) is a medium-sized rodent, diurnal, and characteristic of northeastern Brazil, south of the Amazon. Several studies have been made on these rodents. However, there is a lack of analysis of masticatory system, in particular morphology of the teeth. Thus, this research seeks to describe anatomical and histological aspects of the agouti teeth. For this purpose, we used adult agouti, in which measurements and descriptions of teeth and dental tissues were made. It was observed that the dental arch of D. prymnolopha comprises of twenty teeth, evenly distributed in the upper and lower arch, being inferior teeth larger than their corresponding higher. The incisors are larger, and between the posterior premolars and molars, there is a gradual increase in length in the anterior-posterior arch. In microscopic examination, a prismatic appearance was observed consisting of enamel prisms arranged in different directions, behind the enamel and dentin with standard tubular dentinal tubules with variable diameter and far between, also showing a sinuous path from the inner portion to the junction with more superficial enamel. Morphological analysis of dental tissues showed that an enamel with structural organization adapted to the act of chewing and high impact dentin compatible with standard tubular function resilience and mechanical damping of masticatory forces, as found in larger animals, confirming the understanding of eating habits that define much of its ecological functions within the ecosystem they inhabit.

Wear resistance of experimental titanium alloys for dental applications

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oral cavity evaluation and dental chart registration of coati (Nasua nasua) in captivity

The aims of this study were to develop a dental chart evaluate any oral cavity disease, develop gypsum models the dental arches, and to register the occlusions found in coatis (Nasua nasua) in captivity. Formulation of the dental chart was assisted by intraoral radiographs from the head of an adult coati cadaver of the same species with the following dental formula: I 3/3, C 1/1, P 4/3, M 2/2. Seven live coatis of the Nasua nasua species were evaluated. Five of the seven coatis presented with various dental abnormalities as follows: dental plaque (71.4 %), gingivitis (71.4 %), periodontitis (57.1 %), dental stain (42.9 %), dental abrasion (57.1 %), dental fracture (57.1 %), pulp exposure (42.9 %), malocclusion (5 7.1 %) and supernumerary teeth (14.2 %).

The association between prune belly syndrome and dental anomalies: a case report

Background: Prune belly syndrome is a rare condition produced by an early mesodermal defect that causes abdominal abnormalities. However, the literature indicates that disturbances related to ectodermal development may also be present. This is the first case report in the literature to suggest that dental abnormalities are part of the broad spectrum of clinical features of prune belly syndrome. Because the syndrome causes many serious medical problems, early diagnosis of abnormalities involving the primary and permanent dentitions are encouraged.Case presentation: The authors report the clinical case of a 4-year-old Caucasian boy with prune belly syndrome. In addition to the triad of abdominal muscle deficiency, abnormalities of the gastrointestinal and urinary tracts, and cryptorchidism, a geminated mandibular right central incisor, agenesis of a mandibular permanent left incisor, and congenitally missing primary teeth (namely, the mandibular right and left lateral incisors) were noted.Conclusion: This original case report about prune belly syndrome highlights the possibility that dental abnormalities are a part of the broad spectrum of clinical features of the syndrome. Therefore, an accurate intra-oral clinical examination and radiographic evaluation are required for patients with this syndrome in order to provide an early diagnosis of abnormalities involving the primary and permanent dentitions.

Preparation of new glass systems by the polymeric precursor method for dental applications

Glass ionomer cements (GICs) are largely employed in Dentistry for several applications, such as luting cements for the attachment of crowns, bridges, and orthodontic brackets as well as restorative materials. The development of new glass systems is very important in Dentistry to improve of the mechanical properties and chemical stability. The aim of this study is the preparation of two glass systems containing niobium in their compositions for use as GICs. Glass systems based on the composition SiO2,Al2O3-Nb2O5-CaO were prepared by chemical route at 700degreesC. The XRD and DTA results confirmed that the prepared materials are glasses. The structures of the obtained glasses were compared to commercial material using FTIR, Al-27 and Si-29 MAS-NMR. The analysis of FTIR and MAS-NMR spectra indicated that the systems developed and commercial material are formed by SiO4 and AlO4 linked tetrahedra. These structures are essential to get the set time control and to have cements. These results encourage further applications of the experimental glasses in the formation of GICs. (C) 2004 Elsevier B.V. All rights reserved.

Loss of space and dental arch length after the loss of the lower first primary molar: A longitudinal study

The premature loss of primary teeth may harm the normal occlusal development, although there are debates relating to the necessity of using space maintainer appliances. The aim of the study is to evaluate the changes in the dental arch perimeter and the space reduction after the premature loss of the lower first primary molar in the mixed dentition stage. The sample consists of 4 lower arch plaster models of 31 patients, within the period of pre-extraction, 6, 12 and 18 months after the lower first primary molar extraction. A reduction of space was noted with the cuspid dislocation and the permanent incisors moving toward the space of the extraction site. It was concluded that the lower first molar primary premature loss, during the mixed dentition, implicates an immediate placement of a space maintainer.

Anatomical and histological characteristics of teeth in agouti (Dasyprocta prymnolopha Wagler, 1831)

A cutia espécie Dasyprocta prymnolopha (D. prymnolopha) é um roedor de tamanho médio, diurno e característico do Nordeste do Brasil, sul da Amazônia. Vários estudos têm sido feitos sobre estes roedores. No entanto, há uma carência de estudos do sistema estomatognático, em particular, a morfologia dos dentes. Assim, esta pesquisa procura descrever aspectos anatômicos e histológicos dos dentes cutia. Para isto, nós utilizamos cutias adultas, em que as mensurações e as descrições dos dentes e dos tecidos dentais foram feitas. Observou-se que a arcada dentária de D. prymnolopha é composta por vinte dentes, distribuídas uniformemente no arco superior e inferior, sendo os dentes inferiores, maiores do que os seus correspondentes superiores. Os incisivos são maiores, e entre os pré-molares e molares posteriores, existe um aumento gradual no comprimento do arco anterior-posterior. No exame microscópico, uma forma prismática foi observada o que consiste de prismas de esmalte dispostos em diferentes direções, atrás do esmalte e dentina com túbulos dentinários com padrão tubular de diâmetro variável e distantes entre si, mostrando também um caminho sinuoso a partir da parte interna da junção com o esmalte mais superficial. A análise morfológica dos tecidos dentários mostrou um esmalte com a organização estrutural adaptada para o ato de mastigar e dentina de alto impacto compatível com a função do padrão tubular de resiliência e amortecimento mecânico de forças mastigatórias, como encontrado em animais maiores, confirmando o entendimento de hábitos alimentares que definem muito das suas funções ecológicas dentro do ecossistema em que vivem.

Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Direct Spectrometry: A New Alternative for Measuring the Fluorescence of Composite Resins and Dental Tissues

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of standard load micro and nanopatterned in surface roughness of bleached teeth and submitted to different surface treatments?

The aim of this study was evaluate the dental enamel after whitening treatment with Opalescence Boost PF® 38%, correlating the structural alterations in the surface of the enamel with its respective pH and verify if whitened teeth submitted to different finishing and polishing techniques show similar surface texture to healthy teeth (control group). Sixty premolars were divided in 6 groups (n = 10), which had been immersed in artificial saliva during all the experiment. Protocol whitening was performed according to the manufacturer recommendations, and then the specimens were submitted to different polishing technique with Sof-Lex Pop On® disks, Flex Diamond® felt disks using two different micrometric polishing pastes (Enamelize® and Diamond Polish®) and two nanometric polishing pastes (Lummina-E Diamond and Lummina-E Alumina), according to the groups. Representative specimens were analyzed in scanning electronic microscopy (SEM). Whitening gel used in this experiment had modified the morphologic aspect of the enamel surface. It was found that two nanometric polishing pastes (G5 and G6) promoted a less rough surface compared to control group even after the whitening process.

Optimizing maxillary aesthetics of a severe compromised tooth through orthodontic movement and dental implants

Treatment of severe compromised tooth in the maxillary anterior area still poses great challenge to the clinicians. Several treatment modalities have been proposed to restore the function and aesthetics in teeth with advanced periodontal disease. The present study aims to report a case of traumatic injury of a left-maxillary central incisor with ridge preservation, orthodontic movement, and implant therapy. A 45-year-old woman underwent the proposed treatment for her left central incisor: basic periodontal therapy, xenogenous bone graft, and guided bone regeneration (GBR). Six months after the graft procedure, orthodontic movement by means of alignment and leveling was made and a coronal displacement of the gingival margin and vertical bone apposition could be observed after 13 months of active movement. Afterwards, a dental implant was placed followed by a connective tissue graft and immediate provisionalization of the crown. In conclusion, orthodontic movement was effective to improve the gingival tissue and alveolar bone prior to implant placement favoring the aesthetic results. Six years postoperatively, the results revealed height and width alveolar bone gain indicating that the treatment proposed was able to restore all the functional and aesthetic parameters.

Improved response of the Ti30Ta experimental alloy after surface treatment for dental applications

The purpose of the study was to evaluate the influence of the biomimetic surface treatment in osseointegration of experimental alloy Ti30Ta for dentistry applications. Methods and materials: Experimental alloy with Ta concentration of 30 wt% was produced from sheets of commercially pure titanium (99.9%) and tantalum (99.9%). Ingots were melted in an arc furnace under an argon atmosphere and re-melted ten times at least. They were homogenized under vacuum at 1100 °C for 86.4 ks to eliminate chemical segregation and cold-worked by swaging. Implants with 2.5 mm diameter and 2.0 mm of height were machined (Fig. 1a), treated and inserted in animals for in vivo study. The implants were submitted surface treatment according methodology development for our group. Analyzes were performed by Scanning Electron microscopy (SEM), Atomic Force Microscopy (AFM). Osteoblast morphology on Ti-30Ta alloys was examined after 4 and 7 days of incubation with MSCs using SEM imaging.