Journal of Dental School
Year:2009 | Volume:27 | Issue:1 (79)|Papers Count:8

Background and Aim: Facial growth pattern is one of the important factors in orthodontic treatment planning. The aim of this study was to compare the inclination of the posterior teeth in subjects with a normal and vertical growth pattern.Materials & Methods: Fifty 16 to 20 year old individuals having no history of orthodontic treatment, dental extraction, spacing and crowding in posterior teeth were selected for this case - control study. These individuals were divided into two groups of vertical and normal growth patterns based on SN-MP and jarabak Index. Study casts provided for these patients were trimmed from anterior to the second premolar and from posterior to the first molar.Lateral surfaces of casts were trimmed perpendicular to the occlusal surface tangential to the most prominent cusps of these 4 or at least 3 (two molars and one premolar) teeth. The angle between lateral surface of the cast and the occlusal surface of each tooth was considered as axial inclination. The results were statistically analyzed using Mann Whitney U and t tests.Results: The mean age of the studied group was 18.3±1.6 The mean axial inclination of maxillary first permanent molar with normal growth pattern was 27.5±16.8 (right side) and 26.2±14.7 (left side). The amount of this variable with vertical growth pattern was 23.4±11.9 (right side) and 24.8±14.7 (left side). The mean axial inclination of mandibular first permanent molar with normal growth pattern was 27.24±15.2 (right side) and 27.44±14.8 (left side) and with vertical growth pattern was 23.8±13.9 (right side) and 23.5±14.3 (left side).Conclusion: Buccolingual inclination of the teeth has no effect on orthodontic treatment planning.

Background and Aim: Sealing occlusal fissure of posterior teeth is proved to be an effective approach in prevention of fissure caries. The aim of this in vitro study was to assess the level of microleakage at the sealant/tooth interface of four differently prepared enamel surfaces using Er, Cr:YSGG laser energy with and without additional routine acid.Materials & Methods: A total of 60 sound extracted premolars were included in this in vitro investigation. Samples were randomly assigned to four groups of control (using acid etching technique), laser alone Er, Cr: YSGG Laser radiation with power of 2w, RR: 20 HZ, Pd: 7601ls, and a supplemental etching before lor after laser application in 3rd and 4th Groups, Respectively. Prepared fissures were then sealed using Clin-pro TM sealant (3M, USA). Cases were then thermo cycled for 500 cycles in 5oC and 55oC followed by immersion of Subjects to a 1% methylene blue dye for 48 hrs. This was to enable microleakage assessment. Collected data was then analyzed using Kruskal-Wallis test.Results: No significant differences were found between the classical preparation techniques (Acid etching) and other three experimental groups. The degree of dye Penetration was found to be at its lowest level in the laser-prepared group alone followed by acid etching alone. However further laser intervention of acid etched surfaces was proved beneficial.Conclusion: Additional use of acid etching preparation after Er, Cr: YSGG laser application was shown to be superior to the individual use of acid or laser for enamel preparation, as the result of this study indicated a lower microleakage level on samples treated this way.

Background and Aim: Little is known concerning factors influencing the retention of fixed prostheses cemented to implant abutments. The purpose of this study was to investigate the effect of varying screw access channel filling methods on the retention of implant-supported prosthesis.Materials & Methods: To perform this experimental study, forty titanium implant abutments (Biohorizons) were placed in implant analogues. Implant analogues were mounted in acrylic resin blocks using surveyor. After fabrication of crowns for each abutment, 3.5 mm of the flat axial wall of all abutments was removed. Specimens were divided into 4 groups. In three groups, the screw access channels were fully filled with wax, Polyvinyl Siloxane and Cotosol. In the fourth group, access hole partially filled with wax. Provisional luting agents Temp-Bond, Dycal and Temp- Bond NE were used to secure the crowns to the respective abutments. All specimens were stored in 100% humidity environment prior to testing. Each crown was pulled using a universal testing machine and tensile strength was recorded (N). Data were analyzed using ANDVA.Results: When Dycal was used for cementation, higher tensile strength was observed by partially filled access hole with Wax, fully filled with Wax, Cotosol and Polyvinyl Siloxane respectively. Temp-Bond NE showed significantly higher tensile strength when Polyvinyl Siloxane was used as screw access channel filling material. However, no difference was found in tensile strength of Temp-Bond with different materials used for filling of access hole.Conclusion: The retention of castings cemented to implant abutments with Temp-Bond NE or Dycal is influenced by the filling modality of screw access channel.

Background and Aim: Benign fibrous histiocytoma (BFH) is a rare oral neoplasm particularly in children. Oral BFH is usually painless and found in middle age individuals and mostly affects buccal mucosa. This article describes a case of rare BFH of the oral mucosa that represented high recurrence rate.Case report: The patient reported is a 9-year old girl who was referred for a relatively firm mass about I cm in interdental maxillary incisor. Radiographic examination did not show any particular feature. The mass was excised.Microscopic examination revealed spindle-shaped fibroblastic with vesicular nucleus arranged in fascicule with Storiform pattern, and some histiocyte-like cells. There was no apparent cytologic atypia or any mitotic figures. Evidence suggested benign fibrous histiocytoma (BFH).Conclusion: Although oral benign fibrous histiocytoma (BFH) is a rare lesion, it should be considered in differential diagnosis of oral lesions.

Background and Aim: Early diagnosis of dental problems can prevent so many complications. Treatment of Priority Index (TPI) was introduced by Grainger (1967) for screening and assessing the severity of malocclusion and defines priorities for treatment. The purpose of this study was to evaluate the TPI in the school children (3rd-5th grade) of West Azerbaijan Province in 2005-2006.Materials & Methods: This study was done cross-sectionally with a random cluster sampling method. 550 schoolchildren with mixed dentition were selected. All examinations were done by a trained practitioner, using periodontal probe, tongue blades on a chair in the room light. The TPI of each child was assessed and registered in the questionnaire. The data was analyzed with t-test and ANOVA statistical methods.Results: The average TPI was 2.78±2.65 ranging from 0.27 to 18.17. In 160 cases (29.1%) TPI was in normal range.Whereas 268 persons (48.7%) showed minor manifestations of malocclusion, 83 cases (15.1%) had definite need to treatment. Severe problem was seen in only 29 persons (5.3%) and 10 persons (1.8%) had suffered from very severe problem. No statistically significant difference was found between the mean TPI values of male and female subjects.Conclusion: According to TPI, it seems that half of the population needed slight orthodontic treatment but one-fifth required variety of mandatory orthodontic therapies. This group requires special attention and application of preventive measures.

Background ant Aim: Correct and on time diagnosis of bony lesions of oral cavity provide the possibility of controlling and proper managing for patient and prevent lesion from reaching more advanced stages. The main purpose of this research was to plan and evaluate a decision support system software in order to diagnose the bony lesions of the jaws.Materials & Methods: For the designing the software system the information related to lesions based on books and references were collected and algorithms related to each set of lesions were designed. The algorithms were entered to the decision support system software. Gold Standard for evaluating of software system efficiency were different pictures of bony lesions of Wood text book (Differential Diagnosis of Oral and Maxillofacial Lesions).61 specimens of these lesions with patient's history, rodiographic features and other necessary information were selected to evaluate the software system efficiency. Three observers including specialist in oral medicine, a general dentist, and a dental student provided their diagnosis first without and second with software system. The data were subjected to t test.Results: The, numbers of specimens that have been diagnosed correctly by observer I, without using software system were 61 and again 61 with using software system. The number of specimen that hav~ been diagnosed correctly by the 2nd observer, without using software system were 17 and 46 with using software system. The 3rd observer diagnosed 34 specimens without using the software and 51 with using the software.Conclusion: Algorithms and designed system were useful and reliable for diagnosing the bony lesions of the jaws.

Background and Aim: Membrane is an important factor in regeneration of bony defect. The purpose of this study was to compare the effect of Gutta percha and cytoplast membranes on the regeneration of bony defect in parietal bone of rabbit histologically.Materials & Methods: This experimental histologic study was done on 4 female white Newzland rabbits. 3 bicortical defects were created in parietal bone of each-4 rabbit by 8mm trephine bur. The anterior defects were covered by unresorbable cytoplast –membranes and the posterior defects were covered by Gutta percha membrane (experimental group). The middle defects were not covered by any material (control group). Two rabbits were sacrificed after 20 days and the others after 40 days. The samples were sent for histological examinations.Results: The histological results indicated that the volume of newly formed bone matrix was significantly greater in the experimental groups (cytoplast, gutta percha) than the control groups. But the volume of new bone matrix was not significant between the two experimental groups. The low inflammatory reaction was seen in 20 day's cases. But no inflammatory reaction was seen in 40 days cases.Conclusion: The Gutta percha membrane like cytoplast membrane has biocompatibility and space making properties that could promote bone regeneration.

Background and Aim: Squamous cell carcinoma (SCC) constitutes 94% of oral malignancies. In recent decade many molecular and genetic changes have been known to affect tumoral behavior which might be good targets for new drug production. It is known that expression of EGF is correlated with poor prognosis and expression of laminin- 5 can lead to the development of premalignant lesions to in situ or invasive malignancies. The aim of this study was to determine the correlation between the expression of EGFR and laminin- 5 with clinical stage and microscopic grade of oral see.Materials & Methods: Forty two paraffin blocks with diagnosis of see were collected from oral pathology department of Shahid Beheshti dental school. Immunohistochemical staining was performed with antibodies against EGFR and laminin -5. Two pathologists counted the number of stained cells under light microscope and expression of these two markers was compared by Kendal test.Results: No significant correlation was found between expression of EGFR and tumoral stage and grade. But a significant correlation was found between the expression of laminin-5 with tumoral grade and stage was found (p<0.01).Conclusion: It is concluded that laminin-5 is a marker with a significant effect in developing of a higher tumoral stage and grade but more precise researches are needed to identifying the role of EGFR.