Cette thèse porte sur les capacités de lecture des enfants souffrant de troubles spécifiques du langage oral (TSLO). Elle tente de préciser les processus à l’oeuvre lors de la lecture de mots isolés chez ces enfants, en analysant leurs compétences langagières écrites en lien avec leurs compétences orales. Dans un premier temps, nous présentons les principaux acquis de la littérature à ce propos. Puis nous exposons quatre études expérimentales réalisées auprès d’enfants avec un TSLO ainsi qu’auprès d’enfants au développement typique, sur les sujets suivants : (1) la reconnaissance de mots écrits isolés en lecture à voix haute, (2) la reconnaissance de mots écrits isolés en lecture silencieuse, (3) la compréhension de mots écrits, (4) et les facteurs prédictifs de la lecture. Les résultats les plus marquants indiquent qu’en reconnaissance de mots écrits, les enfants avec un TSLO présentent un retard d’un peu plus de trois ans, en lecture à voix haute comme en lecture silencieuse. En tant que groupe, leur procédure de lecture phonologique apparaît moins efficiente que leur procédure orthographique. L’hétérogénéité interindividuelle demeure toutefois importante. Les enfants qui souffrent des troubles phonologiques expressifs les plus sévères sont ceux dont la procédure phonologique est la plus altérée. Quant à la compréhension de mots écrits isolés, elle apparaît coûteuse en termes de ressources de traitement. Enfin, les facteurs prédictifs de la lecture des enfants avec un TSLO sont identiques à ceux des enfants au développement typique, à l’exception d’un facteur original : chez les enfants avec un TSLO, l’instabilité phonologique est prédictive des capacités de lecture, contrairement aux enfants contrôles. Ce facteur mériterait de plus amples recherches. / This thesis is concerned with the reading abilities in children with specific language impairment (SLI). It aims to precise the process involved when these children read isolated words, by analyzing their written language abilities in relation to their spoken language abilities. Firstly, the main findings of the literature on this topic are presented. Then, four experimental studies conducted both in children with SLI and typically developing children are described. These studies deal with: (1) identification of isolated written words in reading aloud, (2) identification of isolated written words in silent reading, (3) written word comprehension, (4) and predictive factors of reading. The striking results of these studies indicate that, in written word identification in reading aloud, as well as in silent reading, children with SLI show an average delay of about three years, compared to reading control children. As a group, their phonological procedure is less efficient than their orthographic procedure. However, interindividual heterogeneity remains high. The children with the most severe impairment in language production at the phonological level are those with the greatest deficit in the phonological reading procedure. Isolated word comprehension, as for it, appears to be costly in terms of processing abilities. Finally, children with SLI display the same predictive factors of reading as typically developing children, with the exception of inconsistency in speech production, which is a reading predictor specific to children with SLI. Further research about this inconsistency would be useful.

Bisphosphonates are non-metabolized compounds with high affinity for bone mineral hydroxyapatite. These compounds are used in diagnosis and treatment of malignancies metastatic to bone. Currently, IV bisphosphonates are used to treat hypercalcemia of malignancy. There are also "off label" uses to prevent, minimize, or delay skeletal morbidity associated with metastatic bone disease. Osteonecrosis of the jaws is an intraoral complication that has been reported after administration of intravenous nitrogen-containing bisphosphonates. Bisphosphonate associated osteonecrosis (BON) may remain asymptomatic for many weeks or months and is usually recognized clinically by the identification of exposed bone in the oral cavity. Other clinical features of BON are pain, ulceration, necrotic bone and/or local inflammation of the mucosa. Though these are generally all of which are seen later in the disease process. It is theorized that nuclear medicine imaging may play a crucial role in the recognition and identification of these bone lesions earlier in the disease process. Due to the high bone affinity, bisphosphonates coupled to a gamma-emitting radioisotope have been used as bone-scanning agents. Technetium is most commonly used gamma-emitting radioisotope in conjunction with a bisphosphonate. In University of Iowa Hospitals and Clinics, the material of choice is technetium99 methylene diophosphonate (Tc99 MDP). Bisphosphonates have a long half-life in bone and long-term treatment with non-tagged therapeutic bisphosphonates may saturate bone adherence sites and interfering with a single-dose scanning agent used for bone scintigraphy. Alternatively, therapeutic bisphosphonates may alter bone physiology such that scintigraphic findings could be enhanced in some locations and decreased in others. Limitations of the use of scintigraphy in patients on bisphosphonate therapy include low resolution and a difficulty in differentiating between inflammation and metastatic disease especially during the latter stages of the disease. In an effort to understand the effects of this compound on scintigraphic imaging, this study will evaluate any potential changes during and after use of IV bisphosphonates that may confound imaging.

Objectives: The aim of the study was to evaluate in vitro the 3D and 2D marginal fit and 2D internal fit of CAD and Press all-ceramic crowns made from digital and conventional impressions. Methods: A dentoform replica tooth (#30) was prepared for an all-ceramic crown (Master Die). 30 impressions were made with PVS material; 30 definitive casts were poured in type IV gypsum. 30 LavaTM C.O.S. impressions were made; 30 resin models were produced. 30 crowns were waxed and pressed in lithium disilicate (IPS e.max Press) (15 from each impression technique) and 30 crowns were milled from lithium disilicate blocks (IPS e.max CAD) (15 from each impression technique) utilizing the E4D scanner and milling engine. The Master Die and the intaglio of the 60 crowns were digitized using a 3D laser coordinate measurement machine (CMM). For each specimen a separate data set was created for the Qualify 2012 software. The two data sets, digital master die and digital intaglio of the crown, were merged using Best-Fit alignment. An area above the cavosurface margin with 0.75mm occlusal-gingival width circumferentially was defined. The 3D marginal fit of each specimen was an average of all 3D measurement values on that specified area for all the crowns, and it was used for the statistical analysis. For the 2D measurements, two sections, one facial-lingual and one mesial-distal, were made through the grooves on the standardized metal base of the tooth. The distance between the die and the intaglio surface of the crown were measured at 7 standardize points (2 on the margins, 2 at 0.75mm above the margin, 2 on the axial walls and 1 on the occlusal surface). For the 3D measurements one-way ANOVA with post-hoc Tukey's HSD test was used to determine whether there were significant differences in mean marginal fit values among four experimental groups (alpha=0.05). For the 2D data, a two-way ANOVA was performed to detect a significant interaction between the type of impressions and the type of crowns on the marginal and internal fit (alpha=0.05). Results: One-way ANOVA revealed that the 3D mean marginal fit for Group A (0.048mm±SD 0.009) was significantly lower than those obtained from other three experimental groups Group B (0.088mm±SD 0.024), Group C (0.089mm±SD 0.020) and Group D (0.084mm±SD 0.021), while no significant differences were found among Group B, C and D. Similar results were found regarding the 2D marginal fit Group A (0.040mm±SD 0.008), Group B (0.076mm±SD 0.0234), Group C (0.075mm±SD 0.0148) and Group D (0.073mm±SD 0.0258). For the 2D internal fit, Group C (0.2109mm±SD 0.0410) had statistically significant poorer internal fit than the other three groups Group A (0.1105mm±SD 0.0474), Group B (0.1158±SD 0.02) and Group D (0.1454MM±SD 0.0245), while no significant difference was found among those three groups. Conclusions: The combination of PVS impression method and Press fabrication technique produced the most accurate 3D and 2D marginal adaptation. The combination of LavaTM C.O.S. impression and Press fabrication technique produced the poorer 2D internal fit.

No description available.

An exciting alternative to the current methods for bone regeneration is osseous tissue engineering. One such method focuses on enhancement of osteoblast differentiation through rotary cell culture techniques. The response of osteoblast aggregates to periodontal microorganisms and their by-products will ultimately be important in their success as a method of bone regeneration. In this study, I hypothesize that human embryonic palatal mesenchymal (HEPM, ATCC 1486) pre-osteoblast cells produce different cytokine responses depending upon whether they are grown in a 2-dimensional tissue culture flask or a 3-dimensional tissue culture vessel and whether they are exposed to an un-inoculated, sterile Porphyromonas gingivalis growth medium or exposed to a 24 hour, sterile, P. gingivalis culture supernatant. Objectives: My objectives were first to determine and compare the cytokine response of HEPM, ATCC 1486 pre-osteoblast cells depending upon whether they are grown in a 2-dimensional tissue culture flask or a 3-dimensional tissue culture vessel and whether they are exposed to an un-inoculated, sterile P. gingivalis growth medium or exposed to a 24 hour, sterile, P. gingivalis culture supernatant. Methods: In 3 experiments, 5 X 106 HEPM, ATCC 1486 cells were grown in a 2-dimensional tissue culture flask or a 3-dimensional tissue culture vessel and exposed to an un-inoculated, sterile P. gingivalis growth medium or exposed to a 24 hour, sterile, P. gingivalis culture supernatant and incubated for 72 hours in 5% CO2 at 37oC. Media was removed from the tissue culture flasks or rotary vessels at 0, 1, 2, 4, 8, 12, 24, 36, 48, 60, and 72 hours to determine cytokine concentrations in the Luminex 100 IS Instrument (Luminex®, Austin, TX). HEPM, ATCC 1486 pre-osteoblast cell morphology was assessed by light and scanning electron microscopy at 96 hours. Results: In experiment 1, there were increases in IL-6 and IL-8. The IL-6 response of cells grown in a 2-dimensional tissue culture flask was higher than that of cells grown in a 3-dimensional tissue culture vessel. The IL-8 responses of the cells grown in 2-dimensional, 3-dimensional tissue culture were nearly identical. In light and scanning electron microscopy cells appeared normal and HEPM, ATCC 1486 pre-osteoblast cell aggregates were similar to that previously reported. In experiment 2, there were also increases in IL-6 and IL-8. The IL-6 and IL-8 responses of HEPM, ATCC 1486 pre-osteoblast cells grown in a 3-dimensional tissue culture vessel exposed to a 24-hour, sterile, P. gingivalis culture supernatant were higher than cells exposed to un-inoculated, sterile P. gingivalis growth media. In experiment 3, HEPM, ATCC 1486 pre-osteoblast cells grown in 2-dimensional tissue culture flasks and 3-dimensional tissue culture vessel exposed to a 24 hour, sterile, P. gingivalis culture supernatant produced high levels of IL-6, IL-8, and VEGF. Again, in light and scanning electron microscopy, cells appeared normal. Conclusion: HEPM, ATCC 1486 pre-osteoblast cells display different cytokine profiles depending upon the type of vessel they are cultured in. They also rigorously respond to P. gingivalis culture supernatants suggesting that they may respond to the presence of microorganisms commonly found in the oral cavity and play an active role in immunity during their integration following bone regeneration.

Objectives: Meta-analysis was used to quantitatively synthesize results from clinical studies comparing four percent articaine hydrochloride to two percent lidocaine hydrochloride, both with epinephrine 1:100,000. The null hypothesis was that there is no statistically significant difference in efficacy of the two anesthetic agents. Methods: Potential studies for inclusion were identified using the MeSH database search terms carticaine (articaine MeSH term) and lidocaine in a PubMed search. Inclusion criteria included randomized clinical trials in humans with a clear determination of anesthetic efficacy with respect to initial administration of these two anesthetic agents in dental applications. Twelve randomized, clinical trials met the inclusion criteria. The overall approach of this meta-analysis emphasized the pulpal anesthetic success (by means of electric pulp test and/or visual analog scale for intra-operative pain); secondary analyses evaluated timelines of pulpal anesthesia. The combined results for percentage of teeth achieving pulpal anesthetic success were based on the reported data from ten suitable studies, using the Fisher meta-analytic method of combining significance probabilities. Results: Individually, two of these studies reported significantly superior performance of articaine hydrocholoride compared to lidocaine hydrochloride on the basis of achievement of pulpal anesthetic success; a third study reported a suggestive result (p=0.057). In four additional studies, the observed rate of anesthetic success was greater for articaine hydrocholoride, although not significantly so; the performance of the two anesthetic agents was identical in the remaining three studies. Differences in anesthetic success based upon tooth type/location and injection type were explored. Further results were obtained for pulpal anesthetic timelines. Conclusions: The overall result for anesthetic success based upon meta-analysis by the Fisher method was that articaine hydrochloride demonstrated statistically superior efficacy (p=0.004) relative to lidocaine hydrochloride. Supported by the University of Iowa Department of Endodontics.

Objectives: Tooth extraction initiates a cascade of biological events leading to the reduction of alveolar ridge volume. Alveolar ridge preservation (ARP) is a surgical treatment which aims at minimizing hard and soft tissue changes following tooth extraction. Several techniques and materials have been studied and used clinically in ARP. The selection of the biomaterials used for this technique is determined by several factors, such as features of the extraction site, inherent biomaterial properties and handling preferences by the surgeon, among others. The purpose of this study was to evaluate the efficacy of alveolar ridge preservation via the application of Easy-graft CLASSIC® (Sunstar Americas Inc.), an alloplastic bone substitute with unique handling features, following flapless posterior single tooth extraction compared to a particulate freeze-dried bone allograft (FDBA) covered with a collagen wound dressing, which has been advocated as a predictable treatment modality. The primary outcome in this study was bone volumetric reduction of the alveolar ridge assessed using cone beam computed tomography (CBCT) scans obtained at baseline and 16 weeks after tooth extraction and ARP. Methods: This study is part of a multicenter study in collaboration with the University of Maryland School of Dentistry. Seventeen healthy adults treatment planned for a single tooth implants in the area posterior to the canines, excluding third molars, were recruited on the basis of an eligibility criteria. Patients were randomly assigned to the control group or the experimental group. Minimally traumatic extraction of the tooth was completed and the presence of an intact buccal plate of bone was verified. The control group received FDBA and the site was stabilized with a collagen wound dressing and sutures. The experimental group received Easy-graft CLASSIC® with no attempt to approximate the marginal mucosa. Healing was assessed after 1, 2, 4, 8, and 16 weeks. DICOM data was used to assess the alveolar ridge volume and linear changes from baseline to 16 weeks after ARP. Clinical measurements of the buccal gingival thickness, buccal alveolar bone thickness, keratinized gingiva, and socket dimensions were made at the time of the extraction and were subsequently analyzed for possible influences on the observed volumetric and linear outcomes. Results: The mean alveolar ridge volume reduction from baseline to 16 weeks post operatively for the control and the experimental group was 114.96 mm3 and 94.87 mm3, respectively. These values correspond to a reduction of 9.59% for the control group and 13.04% for the experimental group. This difference did not reach statistical significance. The average loss of ridge width was 1.10mm for the FDBA and 1.24mm for the Easy-graft CLASSIC® with no statically significant differences between the two groups. The average loss of buccal bone height and lingual bone height in the FDBA group was 1.12mm and 0.63mm, respectively. Similarly, the average loss of buccal bone height and lingual bone height in the Easy-graft CLASSIC® was 1.19mm and 0.67mm, respectively. There was a weak to moderate positive correlation between buccal tissue thickness and the thickness of the buccal bone and a weak negative correlation between buccal bone thickness and alveolar ridge width reduction. Conclusions: Within the limitations of this study, both treatment groups appear to be effective in alveolar ridge preservation and are associated with similar volumetric and linear bone reduction patterns.

Long-chain bases (sphingosine, dihydrosphingosine, and phytosphingosine) are present in the oral cavity and have potent antimicrobial activity against oral pathogens. However, little is known about their cytotoxicity for oral cells, an important step in considering their potential as future antimicrobial agents for oral infections. In this study, primary oral keratinocytes, primary oral fibroblasts, dendritic cells, and oral squamous cell carcinoma cells were exposed to 10.0-640.0 µM long-chain bases and glycerol monolaurate (GML) in cell culture medium containing resazurin (e.g., Alamar Blue, Invitrogen Corp., Carlsbad, CA). Cell metabolism was assessed at 48 hours by the reduction of resazurin to resorufin. Percent cytotoxicity was defined as the median fluorescence intensity (MFI) of resazurin in cell culture media of cells treated with dilutions of long-chain bases/MFI of resazurin in cell culture media of untreated cells x 100, and the lethal dose 50 (LD50) was determined from the dose response curve where the 50 percent cytotoxicity intercepts with the long-chain base concentration on the x-axis. For all cells, the LD50 (mean µM + std err) of sphingosine, dihydrosphingosine, phytosphingosine, and GML were 69.7 (1.7), 29.2 (1.7), 20.6 (1.7), and 134.3 (1.7), respectively. Primary oral keratinocytes were more resistant to long chain bases, whereas oral fibroblasts, dendritic cells, and oral squamous cell carcinoma cells were more susceptible. Overall, long chain bases have LD50 for oral keratinocytes, oral fibroblasts, dendritic cells, and oral squamous cell carcinoma cells that are considerably higher than the minimal inhibitory concentrations for oral pathogens, a finding important to their future potential as therapeutics for prevention or treatment of periodontal disease infections.

Improper dowel design can cause the failure of a restoration in an endodontically treated single-rooted tooth. A three-dimensional finite element stress analysis was used to evaluate stress patterns on an endodontically treated single-rooted tooth restored with a tapered dowel and core and a complete crown under an angular load applied to the tip of the crown. Results showed that, on the loading side, peak dentin and cement tensile stresses were located at the level of the alveolar crest and at the crown margin, respectively. Increasing the diameter and/or stiffness of the dowel decreased these peak stresses; however, it increased the dentin and cement stresses at the dowel apex level, and at the bone level, respectively. The role of the dowel length was to change the location of the stress concentrations in the dentin occurring at the dowel apex. A large and short dowel or a large and stiff (200 GPa) dowel might cause the root fracture to occur across the dowel apex region. The ferrule had no effect on both the dentin and cement stresses below the alveolar crest level. Increasing the ferrule height diminished the stress propagating in the cement layer from the crown margin toward the tooth-core junction. If root fracture occurred, the model predicted a horizontal fracture when the cement layer was perfectly intact. A vertical root fracture was predicted when the cement was broken at the crown margin on the loaded side. The ferrule effectively prevented the vertical fracture. Reducing the bone height resulted in increasing the dentin and cement stresses at and below the bone level. Extending the crown margin toward the bone level increased the cement stress at the crown margin. With an application of the composite theory, it could be demonstrated that while dowels might increase the stiffness of the system, it might not strengthen the tooth under a transverse loading. In conclusion, dowel diameter, dowel length (below the alveolar crest), dowel material, and ferrule are important factors in predicting the failure of the dowel-core restoration. All factors have to be considered together in the dowel design.

Objectives: Extraction of a tooth leads to a series of healing events that are intimately associated with dimensional changes in the alveolar ridge that typically result in a net volume loss. Previous studies have evaluated the extent and pattern of those resorptive changes, however it remains challenging to predict the degree of change that will occur, as numerous local and systemic factors may play a role in the biologic events that follow tooth extraction. The purpose of this study was to assess the role that phenotypic characteristics of the periodontium play in the alveolar ridge remodeling processes that take place following single tooth extraction. Methods: Healthy patients in need of a single tooth extraction in the maxillary arch from second premolar to second premolar (inclusive) and who met a predefined eligibility criteria were enrolled in this study. An impression of the maxillary arch was made and a cone beam computed tomography (CBCT) scan of the maxilla was obtained immediately prior to tooth extraction at the baseline visit. At the time of the extraction, clinical measurements were made including probing depth, bone sounding, buccal keratinized mucosa width, buccal and palatal alveolar bone thickness, and buccal and palatal soft tissue thickness. Fourteen weeks following the baseline intervention, patients returned to the clinic for a second impression of the maxillary arch and a second CBCT of the maxilla. Linear and volumetric bone measurements were made using the data obtained from the CBCT scans. The casts obtained from the impressions were digitally scanned and volumetric measurements were made from the digitized data to assess volume changes of the residual ridge. The primary outcome of interest was the volumetric percent reduction of the alveolar ridge following single tooth extraction. Spearman correlations were utilized to evaluate relationships between variables and modeling was completed to predict the percentage of volumetric change in the hard and soft tissues using the clinical variables. Results: A total of 21 patients participated in the study, 19 patients are included in this analysis (one patient has yet to complete the study, one patient was later excluded due to lack of compliance). Of the 19 extraction sites included, 17 were maxillary premolar teeth. At baseline, the average buccal plate thickness was 1.09 mm. After 14 weeks, the average loss of alveolar bone width was 1.66 mm. The average loss of buccal bone height was 1.10 mm and mean loss of palatal bone height was 1.36 mm. The average percentage volumetric reduction of the bone as measured from a CBCT scan was 26.42% after 14 weeks of healing. Mean percentage volumetric reduction of the ridge, as measured from a digitized cast, was 18.89%. There was no statistically significant correlation noted between the bone and ridge volumetric measurements. While there were no statistically significant correlations noted between the thickness of the buccal bone and the amount of volumetric remodeling, statistically significant negative correlations were found between the buccal bone thickness and the loss of alveolar bone width (rs = -0.66418, p-value = 0.0019). In addition, a statistically significant correlation was noted between the reduction in alveolar bone width and the loss of buccal ridge height (rs = 0.55707, p-value = 0.0132). Modeling methods found that increased thickness of the buccal soft tissue was predictive of increased percentage volumetric reduction of hard tissues (coeff = 37.24, p-value = 0.0301). Conclusions: Increased buccal soft tissue thickness was found to be predictive of increased percent volumetric reduction of alveolar bone. Thinner buccal bone was correlated with increased loss of alveolar bone width. While statistically significant correlations were identified, further studies with larger sample size are needed to better understand these relationships.