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"Effect of Third Generation Beta-Adrenoceptor Antagonists
With Vasodilating Properties, Carvedilol And Nebivolol, On
Orthodontic Tooth Movement In Rats": Edward El Asmar (Read)
- "Effect of Bilateral Loss of Maxillary Posterior Teeth on the Temporomandibular Joint in Rats": Rabih Antoun(Read)
- "Effect of Autologous Platelet-Rich Plasma on Distraction Osteogenesis in the Mandible of Rabbits": Marc Rahme(Read)
- "Bone Marrow Mesenchymal Scem Cells in Vitro Culture and in Vivo Transplantation": Laeticia Nassif(Read)
- "Effect of Nitric Oxide Enhancer on Orthodontic Tooth Movement in Rats": Edward Asmar
- "Growth Stimulation of Mandibular Condyle by the Effect of Testosterone in Rats": Tarek Shalan
- "Modulation of Myofibroblasts in the Rabbit Wound Healing Experimental Model": Cynthia El-Kahi (More)
- "Effect of Cancer Therapy on Dental and Skeletal Development in Children": Maria Saadeh (More)
- "Relationship Between Severity of Malocclusion and Timing of Adenoidectomy and Tonsillectomy": Anthony T. Macari (More)
- "Craniofacial Anatomy Associated with Class III Malocclusion": Ramzi V. Haddad (More)
- "Detection of Porphyromonac Gingivalis in Pregnant Women with Healthy to Compromised Periodontal Status": Nada M. Souccar (More)
Title: Modulation of Myofibroblasts in the Rabbit Wound Healing Experimental Model
By: Cynthia El-Kahi
Date of Thesis Defense: October 3, 2008
Cutaneous wound healing is a complex process encompassing a number of overlapping phases, including inflammation, epithelialisation, angiogenesis and matrix deposition whereby myofibroblasts are greatly involved. Wound contraction by means of the myofibroblast is a fundamental stage to reestablish the continuity of the wounded area; the latter is characterized by a contractile apparatus in its cytoskeleton especially with the presence of a-smooth actin (aSMA).Treatment with Moist Exposed Burn Ointment (MEBO) seems to enhance wound healing and results in less scar tissue.
To study the modulation of myofibroblasts and integrin avß3 in a full thickness wound performed on rabbits treated with different topical agents.
Full thickness wounds were performed on 16 rabbits divided into four groups. Each group was treated with one of the four followings: (1) Saline, (2) Tegaderm occlusive dressing (3) Silver Sulfadiazine and (4) MEBO. Biopsies were taken on days 0, 4, 8, 12, 16 and 20. They were processed for light microscopy and immuhistochemistry to reveal aSMA and integrin avß3 expressions under the various conditions using fluorescence.
The reepithelialisation was 4 days faster in the MEBO group compared to the other therapies with less edema formation, less inflammatory cells and the lowest TEWL resulting in a soft scar. Even though a-SMA was the highest during the first 12 days in the MEBO group, wound contraction was the least for the same period probably due to a downregulation of the integrin avß3. It seems that the effect of MEBO could be more pronounced on force transmission rather then force generation.
Healing with MEBO showed earlier epithelialisation and decreased activity of myofibroblasts despite the normal levels expression of aSMA, therefore, a better healing quality. The data showed that myofibroblasts can be modulated by topical application of ointments.
Title: Effect of Cancer Therapy on Dental and Skeletal Development in Children
By: Maria Saadeh
Date of Thesis Defense: June 10, 2008
The aim of this study was to determine the impact of anticancer therapy on dental and skeletal maturity.
Material and Methods
The material included panoramic and hand wrist radiographs of 93 children previously or presently treated for cancer matched with healthy controls. Dental age was quantified with 2 commonly used methods (Moorrees - Demirjian). Skeletal age was assessed with the Greulich and Pyle and Tanner-Whitehouse methods. Statistical analyses included t-tests and analyses of variance for group differences in continuous measurements, the Pearson product moment correlation coefficient for associations between various parameters, and linear and multiple regressions for prediction models.
The main results were:
- Chemotherapy has no significant effect on dental maturation. Radiotherapy’s influence is depicted when the jaws are in the direct path of irradiation, mostly in the form of morphological abnormalities.
- In the leukemia patients, a skeletal age retardation of 15 to 20 % was observed with a statistically significant delay of 0.7 years in the high risk group.
- No specific associations were observed for chemotherapy agents, nor for combinations of chemo and radiotherapy.
- The duration of treatment did not have significant effects on dental or skeletal maturation.
- The Demirjian system consistently assigned older dental ages than the Moorrees method.
- The Greulich and Pyle and TW2 bone age systems corresponded in nearly 90% of instances.
Barring the permanent morphological alterations from direct irradiation to the face and jaws, the findings indicate the lack of definitive effect of cancer therapy on dental maturation, and the secondary and probably transient nature of its influence on skeletal development. These conclusions underline definite trends that could be elucidated in larger samples and ideally with longitudinal documentation.
Title: Relationship Between Severity of Malocclusion and Timing of Adenoidectomy and Tonsillectomy
By: Anthony T. Macari
Date of Thesis Defense: February 29, 2008
Airway blockage leads to dentofacial changes culminating in the long-face syndrome or “adenoid facies”, which is difficult to treat back to normal skeletal morphology.
The aim was to evaluate dentofacial changes following nasal obstruction and determine indicators for optimal timing of adenoidotonsillectomy that would avoid or minimize dentofacial alterations.
Cephalographs were taken of 200 Caucasian children (ages:1.71-12.62 years) referred by the pediatric otolaryngologist for cephalometric evaluation of airway obstruction. In addition to conventional angular and linear cephalometric measurements to determine relations among cranial base, maxilla, mandible, and separately the chin, the distances from the soft palate, shortest to the adenoid (SAD), and to the most convex point on the adenoid (CAD) were recorded. Airway clearance was graded (1-3) according to a common rating system of the adenoid blocking various percentages of the airway. Occlusal relations were noted. Statistical analyses included t-tests and analyses of variance for differences in continuous measurements between groups (by age or comparisons to available Caucasian norms), the Pearson product moment correlation coefficient for associations between various parameters, and linear and multiple regressions for associations and prediction models.
Dysmorphology compensatory to nasal obstruction set as early as age 1.7 years, the maxilla often affected first with a posterior-inferior tilt of the palatal plane to the horizontal (PP/H). Other changes occurred separately or together: mandibular antegonial notching, steeper mandibular plane, anterior symphyseal reduction, increased lower face-height. Dental malocclusions included increased overjet with normal or distoclusion, open bite, anterior and posterior crossbite. SAD and maxillary length (ANS-PNS) or inclination (PP/H) accounted for nearly 65% or 60% of the variation in mandibular size, respectively.
Title: Craniofacial Anatomy Associated with Class III Malocclusion
By: Ramzi V. Haddad
Date of Thesis Defense: February 29, 2008
Despite extensive investigation, morphological characteristics of Class III malocclusion warrant study. The objective was to evaluate this malocclusion’s craniofacial anatomy, specifically the relationship between anterior crossbite, cant of the palate and anterior cranial base.
The material included the lateral cephalometric radiographs of two samples: a Class III group (n=142; 80 males, mean age: 15.92+7.62; 62 females, age: 16.56+7.34 years) with a minimal incisal edge to edge relationship, and a Class II, division 1 group (n=84; 41 males, age 10.10+1.55; 43 females, age: 9.72+1.30 years). The radiographs were analyzed following a standardized method. Cephalometric measurements included, among others: overjet (or anterior crossbite); angles ANB, SN to horizontal (H), the saddle angle (articulare-sella-nasion), and the cant of the palatal plane (PP) to SN and to H. Statistical analyses included t-tests and analyses of variance for group differences in continuous measurements, the Pearson product moment correlation coefficient for associations between various parameters, and linear and multiple regressions for prediction models.
In the Class III sample, the anterior cranial base inclination was more cephalad than the average, more in males (5.21o) than females (7.36o; p=0.002). The opposite direction was noted in Class II patients, who were compared with a Class III subgroup, matched for similar age brackets. Statistically significant differences were observed for all measurements except mandibular size and inclination. When both groups were merged to evaluate the continuum of severity from one malocclusion pole to another, high correlations were noted between overjet (OJ) and PP/H (r=-0.82); SN/H and PP/H (r=-0.77), and overjet and SN/H (r=0.67). The findings suggest that the relation of the palate and cranial base to the basic measure of malocclusion (overjet and crossbite) reflects the expectation that any one of them would be associated with or affect the shape of the other(s). Specifically in Class III, (1)-development and/or severity of the dysmorphology may depend on intragrowth orthopedics generated by functional forces transferred through the occlusion to cause maxillary retrognathism that otherwise would not exist. (2) since maxillary retrognathism was on average more severe (SNA=78o; norm=82o) than mandibular prognathism (SNB=81o; norm=80o), mandibular prognathism is not the prevalent component of mesioclusion.
Title: Detection of Porphyromonac Gingivalis in Pregnant Women with Healthy to Compromised Periodontal Status
By: Nada M. Souccar
Date of Thesis Defense: June 11, 2007
Periodontitis is a mixed infection involving multiple bacterial species and host cell interactions. Porphyromonas gingivalis, one of the most studied periodontal pathogens, produces a number of toxins and can invade soft tissues. Its presence in the periodontal pocket depends on the severity of the disease. Recently, periodontitis has been related to many systemic conditions, including adverse pregnancy outcomes. To date, no study involving periodontally challenged Lebanese pregnant women was conducted. The aims of this study were to determine the presence and potential correspondence of P. gingivalis in the dental plaque and the vagina; and determine serum anti-P. gingivalis antibody and C-reactive Protein (CRP) levels and relate the findings to periodontal status and pregnancy complications.
Forty pregnant women in their third trimester were recruited in 2 equal groups according to periodontal status. All personal and dental characteristics were documented. Dental plaque samples and vaginal swabs were tested by PCR for the presence of IS1126, an insertion sequence specific for P. gingivalis. Anti-P. gingivalis antibody and CRP levels in serum were measured by ELISA.
Fifteen oral samples were positive for IS1126, 13 of which belonging to women presenting clinical periodontitis. All vaginal samples tested negative for the same insertion sequence. The antibody titer was increased in 6 of the 15 precited women. CRP titer was increased in 6 patients. All females had no pregnancy complications and delivered on term.
Age and low socio-economic status appear to be important predisposing factors for the establishment of P. gingivalis in the periodontal pocket. These preliminary results suggest timely treatment of periodontitis. However, there does not seem to be a direct effect of periodontal disease on pregnancy outcome in Lebanese women. More research is needed to answer our aims.