Vol 2, No 2 (2005)
Proceeding Abstracts
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Statement of Problem: Nasopharyngeal obstruction by adenoid enlargement is one of the main causes of mouth breathing. Diagnostic indices of nasopharyngeal obstruction by lateral cephalometric radiography are controversial. Purpose: The purpose of this study was to diagnose the nasopharyngeal obstruction by means of lateral cephalometric radiography. Materials and Methods: In this research two groups, (study and control), of 6 to15 years old were studied. In the study group, 46 mouth breathers were clinically examined by an orthodontist and an Otolaryngologist to confirm the nasopharyngeal obstruction. Control group was also comprised of 46 nasal breathers within the same age groups. A lateral cephalogram in centric occlusion was obtained for each patient. After tracing, following 7 nasopharyngeal variables were measured: 1- pp (palatopharyngeal depth). 2- Ad.Pmp (nasopharyngeal airway depth). 3- Air area (nasopharyngeal airway area). 4- NP area (bony area of nasopharynx). 5- Ba.Pmp (bony depth of nasopharynx). 6- d (bony depth of nasopharynx). 7- h (bony height of nasopharynx). Statistical t-test was conducted following calculating the mean, standard deviation and p-value of parameters. Discriminant function analysis was employed subsequent to the t-test for the significant variables, in order to find a method by which the values for several variables could be used simultaneously to determine whether obstruction exists. Qualitative variables of sex and age groups (6-10, 11-12, and 13-15 years old) were also used in discriminant analysis. Results: In the study group, mean value of pp, Ad.pmp, air area, Np area and Ba.pmp were significantly decreased, whereas mean of d and h variables were not considerably lessened. After performing analysis stage, the following discriminant function equation with critical point of 3.88 and correct classification of 94.57% was determined: D=0.345 (pp) +0.064 (Ad.pmp)-0.001(NP area) + 0.03(Air area) +0.505(Age1). If a person’s age is between 6 and 10 years old, we use one instead of Age 1 and if the age is between 11 and 15 years old, we consider zero in place of Age 1. Conclusion: If discriminant score is less than 3.88, the patient has nasopharyngeal obstruction with 94.57% probability.
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Statement of Problem: Considering the importance of the occlusal plane orientation in complete denture prostheses, a study was conducted on the relationship between this plane with ala-tragus and Camper’s lines in soft tissue among individuals with class III malocclusion, in Mashhad School of Dentistry. Purpose: The aim of the present study was to define the best soft tissue index by which the location and inclination of the occlusal plane in complete dentures could be established. Materials and methods: The participants consisted of 13 males with Angle’s class III occlusal relationship. Radiopaque markers were attached to the intended points on soft tissue and then standard lateral cephalograms were obtained from each subject. The angles between the following lines were measured: Occlusal line (OL), Camper's line (ala-porion), AT1 (ala-superior border of tragus), AT2 (ala- mid-tragus) and AT3 (ala-inferior border of tragus). Results: The mean values and standard deviations calculated from the measured variables are as follows: OL-^AT1, 5.65 (3.95) degrees; OL- ^AT2, 3.19 (2.45) degrees; OL- ^AT3, 2.92 (2.42) degrees and OL- ^Camper, 8.5 (3.83) degrees. Comparison of the results by the ANOVA test exhibited a significant difference (F=3.7, P=0.05). As the OL^-AT3 angle had the lowest value, the occlusal line had a stronger tendency to be parallel to the AT3 line. Conclusion: According to the present study, the inferior border of the tragus is suggested as the posterior point for ala-tragus line orientation.
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Statement of Problem: Tongue thrust and/or its consequent swallowing pattern are amongst the parafunctional habits that have always been considered as etiological factors for dental disorders by different investigators. Purpose: The aim of this study was to investigate the prevalence of tongue thrusting and the incidence of periodontal disorders associated with this habit among patients referred to the Department of Periodontology, School of Dentistry, Tehran University of Medical Sciences. Material and Methods: Two hundred and eighty patients, undergoing first phase of periodontal therapy, were selected. Among them, those who had tongue thrusting were diagnosed and periodontal indices (probing depth, gingival recession, spacing and gingival enlargement) were measured. Also, crown-root ratio was assessed for each anterior tooth. Results: Tongue thrusting was seen in 27.3%of patients, whereas 29.8% and 33.8% of them showed an increase in periodontal pocket depths in their upper and lower jaws, respectively. Gingival recession was found in the upper jaw in 12.98% and in the lower jaw in 49.35% of the cases. Crown to root length ratio in 24.6% of the upper incisors and 35.1% of the lower incisors were found to be higher than normal. Spacing was observed between the incisors in 31.2% and 41.6% of the patients in the upper and lower jaws, respectively. Finally 31.2% of the patients showed gingival enlargement. Conclusion: The results of the present study revealed a considerable increase in the prevalence of various periodontal diseases among these subjects. To minimize the clinical problems of such patients, prevention of periodontal diseases through excellent oral hygiene and regular dental visits are suggested.
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Statement of Problem: Considering the cost and amount of time and also the quantity of tooth loss in the process of cavity preparation, repair of the restoration instead of its replacement would be much more efficient. Purpose: The aim of this study was to determine the effect of different methods of surface conditioning on the shear bond strength of repaired compomers. Materials and Methods: Sixty blocks of compomer were prepared in acrylic molds and then they were randomly divided into five groups of 12. Group I (control group) received no treatment. The remaining samples were immersed in 37 ºC distilled water for one week, then the surfaces were roughened with a coarse diamond bur. Samples in each group were prepared by different surface treatment and conditioning: In group II specimens were conditioned with 35% phosphoric acid for 20s. Specimens in group III were etched with 10% polyacrylic acid for 20s. In group IV 1.23% acidulated phosphate fluoride was applied for 30s, and compomer surfaces were sandblasted with 50μm Al2O3 powder in group V. After the initial preparations, all groups were treated with silane and resin before bonding of the second mix of compomer. Shear forces were applied with a universal testing machine at a cross-head speed of 5mm/min. The data were analyzed using one-way ANOVA and Duncan's multiple range tests. Results: The mean shear bond strengths and standard deviations (in parentheses) for groups I to V were 31.56(10.86), 20.02(5.49), 17.74(7.34), 19.31(4.31) and 27.7(6.33) MPa, respectively. The mean bond strengths for Groups I and V were significantly higher than that of the other groups (P<0.05). Conclusion: The results showed that among the surface treatments used in this study, sandblasting with alumina could be the best surface preparation method for repairing compomer restorations.
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Statement of problem: Endodontic treatment of necrotic teeth with open apices is a challenge. After ruling out surgery as a treatment scheme and introduction of the multivisit apexification which in turn had its disadvantages, apical plug seems to be a suitable substitute treatment plan for such cases. Apical plug makes the treatment through formation of a barrier against the obturating material in a single visit. Purpose: The purpose of this study was to compare histologically the periapical healing using MTA and calcium hydroxide apical plugs after intervals of 4 and 12 weeks in cats. Materials and Methods: In this clinical trial study 64 canines of 16 healthy and mature cats were divided into 3 groups after a periapical lesion formation by over instrumentation in the apical area with files up to no.120. The first group included 24 teeth on which MTA apical plug was applied. The second group included 24 teeth on which Ca (OH) 2 apical plug was applied. In both groups the canals were filled with gutta percha and sealer. The third group included 16 control teeth whose canals were left empty after instrumentation and debridement. The access cavities of all teeth were sealed with varnish and amalgam and the vital perfusion of cats was performed in 4 and 12 week intervals. Statistical analysis was established by χ2 and independence test. Results: After 4 weeks, periapical healing in the first group was 90%, in the second group 80% and in the third group, it was only 12.5 %. After 12 weeks, periapical healing occurred in 100% of the MTA group, while it was 57.1% in the second and 40% in the third group .Generally, in the study of histological parameters of healing, no statistical significant difference was observed between the 2 experimental groups, although the MTA group results were much better than the Ca (OH) 2 group especially at 12 weeks. Conclusion: The use of MTA apical plug is more effective than Ca (OH) 2 in treatment of necrotic teeth with open apices.
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Statement of Problem: Glucocorticoid-induced osteoporosis is characterized by a decrease in osteoblast numbers and a marked impairment of new bone formation. Purpose: The ain of present study was to evaluate the effect of methylprednisolone acetate on bone metabolism and bone mineral density in rats. Materials and Methods: Eighteen male Sprague Dawley rats (8 weeks old, weighting 180 gm) were randomly divided into three groups: Group A (n=6), was a baseline control consisting of normal animals. Group B (n=6), was treated only by normal saline injection (0.9%) and group C (n=6), injected Methylprednisolone acetate (0.2 mg/kg/s.c. 3 times/week for 4 weeks). Changes in biochemical agents of serum calcium were evaluated by measuring acid phosphatase and osteocalcin, before and after treatment. Bone mineral density (BMD) of the lumbar vertebrae was also measured by dual energy x-ray absorptiometry (DEXA). Results: The results showed that, serum calcium levels were not affected by methylprednisolone acetate (p>0.05), but acid phosphatase levels of serum increased significantly (p≤0.05). In addition, the serum osteocalcin levels and bone mineral density of lumbar vertebrae decreased significantly (p≤0.05) in the methylprednisolone acetate-treated group as compared to the other groups. Conclusions: The findings indicate that administration of methylprednisolone acetate decreases bone formation and increases bone resorption in the lumbar vertebrae.
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Sialography is the retrograde injection of an iodinated contrast agent into the ductal system of salivary glands and this technique is the only method capable of adequately demonstrating the status of the ductal system. One of the indications of sialography is classification of the salivary ductal system fistulae. This classification has important prognostic and therapeutic values. In the present article, interesting diagnostic findings of combined parotid sialography and extraoral fistulography without using other advanced imaging techniques is discussed in an injured patient.
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A 16 year old female was referred to an oral and maxillofacial radiologist for evaluation of a radiolucent area at mesial radicular aspect of right maxillary central incisor which was detected accidentally during pre-orthodontic treatment check ups. Clinical examination showed no particular signs or symptoms except for slightly tenderness to lateral percussion. Second radiograph with altered horizontal angulations showed a mesial supernumerary root which the radiolucency seemed to be associated with that. In order to treat the tooth, the composite filling was removed and canals were cleaned, shaped, and obturated by lateral condensation technique.
