Identification of novel Factor XI mutations in a patient requiring dental extractions

Factor XI is a serine protease that participates in the intrinsic pathway of blood coagulation. Patients deficient in factor XI exhibit varying degrees of post operative bleeding following invasive surgical procedures such as dental extractions. Objectives: The aim of the study was to identify the specific mutations in a patient from a family with known factor XI deficiency. Methods: Samples were obtained from the patient, his mother and his father and subjected to DNA sequencing. Each protein coding exon 2-15 of the factor XI gene was amplified by polymerase chain reaction (PCR) followed by bidirectional sequencing utilizing di-deoxy chain termination chemistry. Results: The patient had a factor XI level of 20% of normal. Initial sequencing of factor XI from the patient identified a point mutation (646G>A) and a putative splice site mutation (1567+4A>T) in intron 13. These are novel previously unreported mutations. DNA sequence analysis of the mother revealed the 1567+4A>T mutation and the father exhibited the 646G>A mutation. As a consequence the treatment proceeded without serious bleeding complication and required administration only of transexamic acid though factor XI was available as haemostatic cover. Conclusion: The two mutations identified in this family are novel; further laboratory investigation of the functional consequences of those mutations is currently underway. Although factor XI deficiency is rare in the Northern Irish population this study highlights the techniques available to sequence and analyse this and similar haematological disorders.

Tooth replacement for partially dentate elders: a willingness-to-pay analysis

Objectives: The primary aim of this study was to investigate partially dentate elders’ willingness-to-pay (WTP) for two different tooth replacement strategies: using Removable Partial Dentures (RPDs) and, functionally orientated treatment (SDA). The secondary aim was to measure the same patient group’s WTP for dental implants.Methods: Patients who had completed a previous RCT comparing two tooth replacement strategies (RPDs and SDA) were recruited. 59 patients were asked to indicate their WTP for treatment to replace missing teeth in a number of hypothetical scenarios using the payment card method of contingency evaluation coupled to different costs. Data were collected on patients’ social class, longest held occupation, income levels and social circumstances.Results: The median age for the patient sample was 72.0 years (IQR: 71-75 years). Patients who had previously been provided with RPDs indicated that their WTP for this treatment strategy was significantly higher than those patients who had received SDA treatment (Mann-Whitney U Test: p<0.001). This group were also WTP a higher price for SDA treatment than those patients who had previously been treated according to this modality (Mann-Whitney U Test: p=0.005). The results indicated that patients’ age was not correlated with WTP but both social class and current income levels were significantly correlated (Spearman’s rank correlation: p<0.05).Patients in both treatment groups exhibited llittle WTP for dental implant treatment with a median price recorded which was lower than either RPD or SDA treatment.Conclusions: Amongst this patient cohort previous treatment experience had a strong influence on WTP as did social class and current income levels. The patients’ WTP indicated that they did not value dental implants over simpler forms of tooth replacement such as RPDs or a SDA approach.

Active design of tooth profiles using parabolic curve as the line of action

This paper proposes a method for the design of gear tooth profiles using parabolic curve as its line of action. A mathematical model, including the equation of the line of action, the equation of the tooth profile, and the equation of the conjugate tooth profile, is developed based on the meshing theory. The equation of undercutting condition is derived from the model. The influences of the two design parameters, that present the size (or shape) of the parabolic curve relative to the gear size, on the shape of tooth profiles and on the contact ratio are also studied through the design of an example drive. The strength, including the contact and the bending stresses, of the gear drive designed by using the proposed method is analyzed by an FEA simulation. A comparison of the above characteristics of the gear drive designed with the involute gear drive is also carried out in this work. The results confirm that the proposed design method is more flexible to control the shape of the tooth profile by changing the parameters of the parabola.

A method of evaluating psychomotor tooth preparation skills in preclinical dental programs

Preclinical and clinical tooth important and significant aspect of preparation is an a dental student's education. The associated procedures rely heavily on the development of particular psychomotor skills. The most common format of instruction and evaluation in tooth preparation at many Dental Faculties, emphasizes the product (tooth preparation) and associates performance with characteristics of this product. This integrated study examines which skills should be developed and how a course of instruction can best be structured to develop the necessary skills. The skills which are identified are those necessary for tooth preparation are selected from a psychomotor taxonomy. The purpose of evaluating these skills is identified. Behavioral objectives are set for student performance and the advisability of establishing standards of performance is examined. After reviewing studies related to learning strategy for dental psychomotor the most suitable tasks as well as articles on instructor effectiveness a model is proposed. A pilot project at the University of Toronto, based on this proposed model is described. The paper concludes wi th a discussion of the implications of this proposed model.

Localización del locus de la enfermedad de Charcot-Marie-Tooth tipo1A : asociación de esta enfermedad con una duplicación de DNA

Tesis (Doctorado en Ciencias con Especialidad en Biología Molecular e Ingeniería Genética) UANL

Effect of osteogenesis imperfecta on orthodontic tooth movement in a mouse model

Thesis written in co-mentorship with director: Nelly Huynh; co-directors: Frank Rauch and Jean-Marc Retrouvey; collaborators: Clarice Nishio, Duy-Dat Vu and Nathalie Alos

Spectroscopic Investigation of Tooth Caries and Demineralization

Dental caries persists to be the most predominant oral disease in spite of remarkable progress made during the past half- century to reduce its prevalence. Early diagnosis of carious lesions is an important factor in the prevention and management of dental caries. Conventional procedures for caries detection involve visual-tactile and radiographic examination, which is considered as “gold standard”. These techniques are subjective and are unable to detect the lesions until they are well advanced and involve about one-third of the thickness of enamel. Therefore, all these factors necessitate the need for the development of new techniques for early diagnosis of carious lesions. Researchers have been trying to develop various instruments based on optical spectroscopic techniques for detection of dental caries during the last two decades. These optical spectroscopic techniques facilitate noninvasive and real-time tissue characterization with reduced radiation exposure to patient, thereby improving the management of dental caries. Nonetheless, a costeffective optical system with adequate sensitivity and specificity for clinical use is still not realized and development of such a system is a challenging task.Two key techniques based on the optical properties of dental hard tissues are discussed in this current thesis, namely laser-induced fluorescence (LIF) and diffuse reflectance (DR) spectroscopy for detection of tooth caries and demineralization. The work described in this thesis is mainly of applied nature, focusing on the analysis of data from in vitro tooth samples and extending these results to diagnose dental caries in a clinical environment. The work mainly aims to improve and contribute to the contemporary research on fluorescence and diffuse reflectance for discriminating different stages of carious lesions. Towards this, a portable and compact laser-induced fluorescence and reflectance spectroscopic system (LIFRS) was developed for point monitoring of fluorescence and diffuse reflectance spectra from tooth samples. The LIFRS system uses either a 337 nm nitrogen laser or a 404 nm diode laser for the excitation of tooth autofluorescence and a white light source (tungsten halogen lamp) for measuring diffuse reflectance.Extensive in vitro studies were carried out on extracted tooth samples to test the applicability of LIFRS system for detecting dental caries, before being tested in a clinical environment. Both LIF and DR studies were performed for diagnosis of dental caries, but special emphasis was given for early detection and also to discriminate between different stages of carious lesions. Further the potential of LIFRS system in detecting demineralization and remineralization were also assessed.In the clinical trial on 105 patients, fluorescence reference standard (FRS) criteria was developed based on LIF spectral ratios (F500/F635 and F500/F680) to discriminate different stages of caries and for early detection of dental caries. The FRS ratio scatter plots developed showed better sensitivity and specificity as compared to clinical and radiographic examination, and the results were validated with the blindtests. Moreover, the LIF spectra were analyzed by curve-fitting using Gaussian spectral functions and the derived curve-fitted parameters such as peak position, Gaussian curve area, amplitude and width were found to be useful for distinguishing different stages of caries. In DR studies, a novel method was established based on DR ratios (R500/R700, R600/R700 and R650/R700) to detect dental caries with improved accuracy. Further the diagnostic accuracy of LIFRS system was evaluated in terms of sensitivity, specificity and area under the ROC curve. On the basis of these results, the LIFRS system was found useful as a valuable adjunct to the clinicians for detecting carious lesions.

Avaliação do risco de ocorrência de lesões de reabsorção dentária em animais com gengivo-estomatite crónica felina

A gengivo-estomatite crónica felina é uma inflamação complexa crónica, com severidade e intensidade variáveis. Apesar de não estar definida a sua etiopatogenia, parece haver uma relação entre a inflamação e a ocorrência de lesões de reabsorção dentária, enquanto causa ou enquanto consequência da doença. O tratamento para as duas doenças é inespecífico, mas baseia-se na extração dentária, contornada ou não com tratamentos médicos. Este estudo teve como objetivo determinar a ocorrência de lesões de reabsorção dentária em gatos com gengivo-estomatite crónica e avaliar a existência de uma possível associação entre um padrão de estomatite crónica e a presença de lesões de reabsorção dentária. O objetivo secundário consistiu na determinação da percentagem de sucesso e o grau de satisfação dos proprietários, após a intervenção cirúrgica. Foram incluídos no estudo 27 gatos. Os critérios de inclusão consistiram no diagnóstico de genvivo-estomatite crónica, realização de um exame radiográfico intraoral completo de todos os dentes, seguido de tratamento cirúrgico, com extrações dentárias e, finalmente, a resposta, por parte dos proprietários, a um questionário. A ocorrência de lesões de reabsorção dentária neste estudo foi de 66,67%. Não foi possível estabelecer nenhuma associação entre a gengivo-estomatite crónica felina e o desenvolvimento de lesões de reabsorção dentária. Os padrões ulcerativos, proliferativos e o de estomatite caudal na gengivo-estomatite crónica felina mostraram risco acrescido para lesões de reabsorção dentária, mas sem significado estatístico. 70,37% dos animais atingiu a cura clínica e 29,63% obteve melhoria global, num período médio de 2 meses. O grau de satisfação dos proprietários obteve uma média de 4,52 valores, numa escala de 1 a 5. Apesar da prevalência elevada de lesões de reabsorção dentária, não foi possível identificar a gengivo-estomatite crónica felina, enquanto fator de risco para a sua ocorrência. À semelhança de estudos anteriores, a gengivo-estomatite crónica felina responde a tratamento cirúrgico com extrações dentárias.

A refined sampling strategy for intra-tooth stable isotope analysis of mammalian enamel

Serial sampling and stable isotope analysis performed along the growth axis of vertebrate tooth enamel records differences attributed to seasonal variation in diet, climate or animal movement. Because several months are required to obtain mature enamel in large mammals, modifications in the isotopic composition of environmental parameters are not instantaneously recorded, and stable isotope analysis of tooth enamel returns a time-averaged signal attenuated in its amplitude relative to the input signal. For convenience, stable isotope profiles are usually determined on the side of the tooth where enamel is thickest. Here we investigate the possibility of improving the time resolution by targeting the side of the tooth where enamel is thinnest. Observation of developing third molars (M3) in sheep shows that the tooth growth rate is not constant but decreases exponentially, while the angle between the first layer of enamel deposited and the enamel–dentine junction increases as a tooth approaches its maximal length. We also noted differences in thickness and geometry of enamel growth between the mesial side (i.e., the side facing the M2) and the buccal side (i.e., the side facing the cheek) of the M3. Carbon and oxygen isotope variations were measured along the M3 teeth from eight sheep raised under controlled conditions. Intra-tooth variability was systematically larger along the mesial side and the difference in amplitude between the two sides was proportional to the time of exposure to the input signal. Although attenuated, the mesial side records variations in the environmental signal more faithfully than the buccal side. This approach can be adapted to other mammals whose teeth show lateral variation in enamel thickness and could potentially be used as an internal check for diagenesis.

Season of birth and sheep husbandry in late Roman and Medieval coastal Flanders: a pilot study using tooth enamel d18O analysis

From the early Roman period, there is archaeological evidence for the exploitation of the Flemish coastal plain (Belgium) for a range of activities, such as sheep herding on the then developing salt-marshes and salt-meadows for the production of wool. During the early Middle Ages, this culminated in the establishment of dedicated ‘sheep estates’. This phase of exploitation was followed by extensive drainage and land reclamation measures in the high Medieval period, transforming areas into grassland, suited for cattle breeding. As part of a larger project investigating the onset, intensification and final decline of sheep management in coastal Flanders in the historical period, this pilot study presents the results of sequential sampling and oxygen isotope analysis of a number of sheep teeth (M2, n = 8) from four late Roman and Medieval sites (dating from 4th to 15th century AD), in order to assess potential variations in season of birth between the different sites and through time. In comparison with published data from herds of known birth season, incremental enamel data from the Flemish sites are consistent with late winter/spring births, with the possibility of some instances of slightly earlier parturition. These findings suggest that manipulation of season of birth was not a feature of the sheep husbandry-based economies of early historic Flanders, further evidencing that wool production was the main purpose of contemporary sheep rearing in the region. Manipulation of season of birth is not likely to have afforded economic advantage in wool-centred economies, unlike in some milk- or meat-based regimes.

Ridge Preservation With Acellular Dermal Matrix and Anorganic Bone Matrix Cell-Binding Peptide P-15 After Tooth Extraction in Humans

Background: Preventing ridge collapse with the extraction of maxillary anterior teeth is vital to an esthetic restorative result. Several regenerative techniques are available and are used for socket preservation. The aim of this study is to analyze by clinical parameters the use of acellular dermal matrix (ADM) and anorganic bovine bone matrix (ABM) with synthetic cell-binding peptide P-15 to preserve alveolar bone after tooth extraction. Methods: Eighteen patients in need of extraction of maxillary anterior teeth were selected and randomly assigned to the test group (ADM plus ABM/P-15) or the control group (ADM only). Clinical measurements were recorded initially and at 6 months after ridge-preservation procedures. Results: In the clinical measurements (external vertical palatal measurement [EVPM], external vertical buccal measurement [EVBM], and alveolar horizontal measurement [AHM]) the statistical analysis showed no difference between test and control groups initially and at 6 months. The intragroup analysis, after 6 months, showed a statistically significant reduction in the measurements for both groups. In the comparison between the two groups, the differences in the test group were as follows: EVPM = 0.83 +/- 1.53 mm; EVBM = 1.20 +/- 2.02 mm; and AHM = 2.53 +/- 1.81 mm. The differences in the control group were as follows: EVPM = 0.87 +/- 1.13 mm; EVBM = 1.50 +/- 1.15 mm; and AHM = 3.40 +/- 1.39 mm. The differences in EVPM and EVBM were not statistically significant; however, in horizontal measurement (AHM), there was a statistically significant difference (P<0.05). Conclusion: The results of this study show that ADM used as membrane associated with ABM/P-15 can be used to reduce buccal-palatal dimensions compared to ADM alone for preservation of the alveolar ridge after extraction of anterior maxillary teeth. J Periodontol 2011;82:72-79.