Journal of Dentistry, Shiraz University of Medical Sciences
Volume:12 Issue: 2, 2011

Statement of Problems: Minimum length of the root end filling material and pulling out of gutta-percha during post space preparation is one of the complications of post insertion in the short root teeth with short root.

The aim of this study was to investigate the coronal leakage of Enterococcus Faecalis in the short root teeth with short root filled with Gutta-Percha and Mineral trioxide aggregate plug. Method and Material: In this in vitro study, 40 single-root extracted human teeth with a root length of 13 mm of root length were selected. Due to the shortnes of the root, 3 mm was considered for canal filling material and 10 mm for the required post space was considered. In order to prepare the canal, filing was done to size 50, using step back technique. No 2, 3 and 4 Gates Glidden was used for post space preparation.The teeth were divided into two experimental groups (Gutta-Percha, MTA) randomly. 15 Fifteen teeth were filled with Gutta-Percha and AH26 sealer using lateral compaction, and then post space was prepared immediately in a wayso that only 3mm of Gutta-Percha remained in the apical part. The other 15 teeth were filled with 3mm MTA plug. Then, ten 10 teeth were used in the positive and negative control groups. In In the positive control group, the teeth were filled with master cone and nowithout sealer and in the negative control group, the teeth were filled with Gutta-Percha and AH26 sealer using lateral compaction.. The working length was 13mm and the coronal parts of the roots was were sealed with stick wax. After the setting time of the filling material, Enterococcus Faecalis was injected into the canals and the teeth were kept in this environment for 120 days. Then, the time of turbidity of each specimens was recorded. Finally, the data were analyzed with using Fisher Exact test.

In the Gutta-Percha group, all the specimens showed leakage between during days 12-35. In the MTA group, leakage was observed in only four specimens between during day 74-113. The positive control group showed leakage in all the specimens during 2 days. none None of the specimens in the negative control group leaked. There was Statistically a statistically significant difference between Gitta-percha and MTA groups (p < 0.001).

Based of on the results of this study, the sealing ability of MTA is better than Gutta-Percha as an ortograde root filling material prepared for post insertion in the teeth with minimum length of root.

Statement of Problem: In diagnostic studies of dentistry, estimation of the mesiodistal width of the unerupted teeth and the required space for their eruption in relation to the space analysis and evaluation of the root-crow ratio is of great importance. This study aimed to evaluate the ratio between the real and radiographic length and mesiodistal width of mandibular premolars and provide a formula for prediction of the teeth length and mesiodistal width. Fifty six extracted teeth of mandibular first and second premolars of patients and their panoramic radiographs with good quality were collected. The extracted teeth were divided into four groups: T34 (lower left first premolar), T44 (lower right first premolar), T35 (lower left second premolar), and T45 (lower right second premolar). Then the length and mesiodistal width of both the panoramic images and the extracted teeth were measured. All of the obtained data were analyzed through t-test, two tailed student and linear regression model. It was shown that the vertical magnification of the mandibular first premolars was almost 11.4%-12.1% and that of the mandibular second premolar was almost 16%. The horizontal magnification of the mandibular first premolar was almost 15% and that of the mandibular second premolar was almost 26%. No statistically significant differences were found between the true and radiographic length and mesiodistal width and the magnifications of the left side premolars compared with right side premolars. To determine the real mesiodistal width and length size, some equations are introduced. The panoramic radiographs taken in this research by X-ray imaging machine are feasible and reliable for estimating the actual premolar teeth length and mesiodistal width using specific equations for each teeth in the lower jaw.

Statement of Problem: Success in pulpectomy of deciduous teeth greatly depends on the accuracy of root length measurements which have mostly been done radiographically. However, X-ray risks and patient cooperation have usually been a challenge for the clinicians. The clinical comparison of root length measurements with electronic apex locator and conventional radiography in 4-6 year old children's mandibular deciduous teeth was the aim of the present study. In the current clinical trial, 15 mandibular molars with 60 canals in 4-6 year old patients who had the treatment plan of pulpectomy were chosen. The measured root lengths with apex locator and parallel technique radiography were evaluated with the same reference point. Data were analyzed using simple linear regression, coefficient of correlation, coefficient of variability and also graphic Bland Altman Plot. The accuracy of electronic apex locator measurements in ±0/5 from apical foramen was 85%. In all cases without considering pulp situation, the difference between the two techniques was not significant. The electronic apex locators are recommended for root length measurements of the deciduous mandibular molars without apical resorption, disregarding the pulp status, especially when initial radiographic films are available.

Statement and Problems: Oral malignant tumors are the eleventh most common malignancy in the world, the most common type of which is oral squamous cell carcinoma (OSCC). It is typically seen in middle-aged to elderly men but it has recently been seen in young adults. The aim of this study was to determine the prevalence of oral squamous cell carcinoma in two different age groups in an Iranian population, and also to compare the related factors in these two groups. The study was descriptive and performed In Imam Khomeiny Cancer Institute, Taleghani and BooAli hospital in Tehran during Apr 2007 to July 2009. Our study group consisted of patients diagnosed with OSCC after biopsy. All demographic data, stage of the disease, occupation, blood group and other risk factors were gathered by reviewing pathological and clinical records. The patients were divided into younger (≤45) and older (>45) age groups and related factors in these groups were compared through Chi-square test in SPSS statistical package (16). Out of 170 patients suffering from OSCC, 138 cases (81.2%) were in the older age group. In this group, there were no statistically significant differences between sex. Tongue and blood group A were the most common site and blood group, respectively (p <0.05). Thirty two patients (18.8%) were in the young group, and mandibular mucosa and floor of the mouth were the most affected site. The great number of the patients were from the north of the country and in stage (IV) of the disease (p <0.05). Oral squamous cell carcinoma is more prevalent in older Iranian patients and the pattern of the disease is different in young patients.

Statement of Problem: In order to decrease microleakage, several preparation methods and cleaning techniques are used on the tooth surface before sealant application has been advocated. These techniques are pumice prophylaxis, fissure enameloplasty, adhesive, laser and air abrasion. The purpose of this in vitro study was to evaluate microleakage of three different preparation techniques before acid etching and pit and fissure sealant application. Sixty extracted sound third molars were randomly divided into 4 groups of 15 each. The teeth were prepared using 1 of the 3 occlusal surface treatments, 1) traditional pumice prophylaxis 2) fissure enameloplasty 3) air abrasion and acid etching. Then the sealant (Clinpro) was applied on the occlusal fissures of all the teeth based on the manufacturer's recommendations. The teeth were thermocycled between 5 and 55 degrees C for 500 cycles with a dwell time of 30 seconds and then stored in normal saline. All the teeth were sealed apically and coated within 1.5 mm of the sealant margin with two layers of nail varnish. They were then immersed in a 0.5% solution of fushin for 24 hours to allow dye penetration into the possible gaps between the enamel and sealant. Buccolingual cuts were made parallel to the long axis of the tooth. The surfaces were scored 0 to 2 for the extent of microleakage using a stereomicroscope. The results were analyzed through mann-Withney test and Mann-Whitney U test. Pretreatment with air abrasion produced the lowest microleakage scores. In the control group, 46.7% microleakage was shown, in the pumice prophylaxis group 40% and in the enameloplasty group 53.3%. There was no significant difference in microleakage between the 3 fissure preparation methods prior to sealant placement (p >0.05). Neither air abrasion nor enameloplasty followed by acid etching produced significantly less fissure sealant microleakage as compared to the traditional pumice prophylaxis technique.

Statement of Problem: Orientation of the occlusal plan in complete denture prostheses therapies plays an important role, leading to appropriate esthetics, stability and mastication. 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. This cross-sectional study consisted of 200 individuals (76 male, 124 female), with the mean age of 26.05 (SD±4.39). In order to determine the relationship between maxillary occlusal plane and ala-tragus line, fox plane and J plane were used. The relationships between maxillary occlusal plane and ALT1 (ala-superior border of tragus), ALT2 (ala-mid-tragus) and ALT3 (ala-inferior border of tragus) were evaluated. In the lower jaw, the occlusal plane was evaluated with the line between the upper and middle parts (ret1) and that between the middle and lower part of retromolar pad (ret2). Data were analyzed by Chi-square test. Evaluation of the difference between the number and percentage using Chi–square test (p < 0.05) showed that there were significant differences between ALT1, ALT2, ALT3 (ALT3 < ALT2 ret2).

Conclusion

Superior one third of the tragus and the upper and middle one third of the retromolar pad are suggested as a reference points for determining the posterior part of the occlusal plane in comparison with the middle and lower one third of the tragus and middle and inferior one third of the retromolarpad.

Statement of Problem: Dental erosion is defined as the loss of tooth substance by chemical processes not involving bacteria. Dental erosion has been found to be a common cause of tooth wear. Clinically apparent erosion has been found to be related to dietary factors such as the acid content of the beverages. Evaluation of enamel erosion in the primary and permanent teeth as the result of two most common acidic drinks produced in Iranian factories, Mirinda and Pepsi. The outermost surfaces of 20 primary and 20 permanent teeth were polished flat by using the finest grade sandpaper and water in order to facilitate the proper measurement. The specimens were then prepared by cutting 3-4 mm of the buccal surface of teeth by diamond burs. The specimens were then rinsed with distilled water and stored in 100˚10 humidity before testing. The surface micro-hardness of each specimen was measured by micro vickers Hardness tester before, after 5 minutes, and 10 minutes exposure to fresh solution of each drink (10 teeth per test group). Mann-Whitney and Wilcoxon signed rank tests were used for the estatistical analysis. The results showed that both drinks, Mirinda and Pepsi, produced significant surface hardness loss at 5 and 10 minutes of exposure time (p =0.05). The amount of erosive effect was changed as the exposure time increased (change from 5 to 10 minutes). There was no statistically significant difference between the amounts of surface hardness loss in the primary and permanent enamel (p >0.05). Both drinks may have almost similar but significant erosive effect on the primary and permanent enamel surfaces. Although there wasn’t any difference between erosive effect of the two beverages, this effect was increased with increase in time. The primary teeth enamel was not found to be more susceptibe to acidic beverage-induced erosion than the permanent teeth.

Statement of Problems: An oral biopsy is essential for definitive diagnosis of oral lesions, and for planning the appropriate treatment. Any fault that happens in biopsy procedures may result in diagnostic errors by pathologists. Thus, inadequate awareness of dentists and patients about biopsy is a significant concern for both of them. The aim of this study was to compare the senior students of dentistry and dental medical doctor's knowledge about harvesting and handling of oral biopsies in Hamadan city. (2009-2010) This cross-sectional study was conducted by using a questionnaire. The data were collected and analyzed through SPSS, version 15. Independent t-test was employed to determine the differences between groups. Of the total 152 collected questionnaires, 42 and 110 were completed by dental students and general dentists, respectively. Accurate responses by the students (72.48±10.76%) was significantly higher than those of the dentists (62.22±14.99 %; p =0.00). There were no significant differences in the correct responses given by female (75±10.11 %) and male (70.20±11.05 %) students and also between female (61.11±14.66 %) and male (62.67±15.19 %) dentists (p >0.05). Among general dentists, the differences of accurate responses between those with professional experience <10 years (62.44±15.64 %) and those with the professional experience >10 years (61.82±13.91 %) were not significant; (p =0.83). This study revealed that dental medical doctor's awareness regarding harvesting and handling of oral biopsies is lower than that of the students of dentistry. Moreover, gender and professional experience did not affect the level of knowledge. Consequently, there is a need for further training in this respect for dental medical doctors.

Despite the absence of any signs of infection in the oral cavity, all dentists and specialists should take prevention of infection and conditions leading to high risk infection into account. Antibiotic prophylaxis could inhibit or lessen the rate of such occurrences.The aim of this review was to describe all risks and side effects of missing prophylaxis and also to mention mechanisms and conditions which precipitate these risks. Hence, we could categorize and exactly define these risks and patients at risk and recommend the best approaches to preventing the risks, selecting antibiotic type, appropriate time for indication, duration of administration, and also all changes based on specific cases.

Statement of Problem: Science production in medical fields such as dentistry is of great significance. Science production can be appropriately directed through recognition of the most effective investigations, the most active institutions and countries in science production domain and also determining the status of specialists. The aim of this survey was to study the rate of dental science production indexed in the Web of Science (WOS) database by Iranian and other countrie's specialists. Using Web of Science, science production in dentistry in 2000-2009 was estimated; revealing 5005 records for scientists around the world and 32 for Iranian specialists. Then, analyses were done using HistCite software. The findings showed that the growth rate of scientific production in dentistry was 64.53% in 2000-2009. USA was in the first rank among other countries; British Dental Journal, Sao Paolo University, and Kokich Vare were the top journal, institution and author, respectively.Data related to Iran showed that Tehran and Shiraz Universities were the first and second top institutions, each with 6 articles. M.H.Fathi with 44 TGCS was the most prolific author in WOS and H.R.Pakshir with 4 TLCS was the most highly published author in WOS in this collection. The findings showed that USA and UK were the first and second top countries in this regard. Iran had only 0.63% of the scientific production of dentistry in the Web of Science database, which is considered low in spite of the importance of this field.

An abnormally small oral orifice is defined as microstomia which is caused by various factors like burning, scleroderma, etc. This disorder is difficult to treat due to the reduced oral opening. In particular, fabrication of removable prostheses is further complicated by tongue rigidity and the constant adjustment required to accommodate the changing periphery; however, successful treatment is possible through specific measures. In this article, a 41-year-old woman living in Baghmalek, Khoozestan was referred to the Prosthodontic department of Jondishapoor University in Ahvaz, southern Iran. She was suffering from microstomia and poor manual ability caused by scleroderma. Initial impression was prepared for her, using Silicon impression material by applying fingers pressure. The final impression was prepared using a two section tray so that the larger part covered one third of the smaller one and both could be attached by compressable button. Then the occlusal relation was established using occlusal rims connected to the two section parcels. Two part parcel prostheses connected with attachments were made for the lower and upper jaws, respectively. The patient was followed up for six months. In order to overcome the above-mentioned problems, the new method of removable prosthesis enjoys the advantage of sufficient precision as well as ease of use by the patient. For further evaluation, diagnosis and proper treatment plan are reported

Autonomic neuropathy is a rare disorder inherited as insensitivity to pain and temperature. It has been divided into five groups, the fourth of which named congenital insensitivity to pain with anhydrosis, (CIPA) is the most common type of this disorder. CIPA is a recessive inherited condition with courses of idiopathic fever, reduction of sweat glands secretion despite having normal glands, insensitivity to pain and temperature changes, and mild mental retardation. Oral symptoms due to their severe abuse in these patients are considerable. Gas shock tongue, lips and other oral mucosa have been reported.Case Report: Examination of a 15 month old boy revealed severe oral ulcers and burns in the fingers of both hands due to contact with the heater. Pathological studies and special attention to specific aspects of the patient revelead that he was insensitive to pain and thermal stimulation and was diagnosed as a possible case of CIPA. CIPA is a autosomal recessive disorder which is very rare in childhood, as insensitivity to pain or the incidence of abuse and lack of objective response to pain in people with peripheral and central nervous system are normal. Tyrosine gene defect related to gene code provided membrane tyrosine has been identified in these patients. Mutation in this gene results in insensitivity to pain, anhydrosis, self abuse, and mental retardation and is associated with cancer. More than half of the patients die before the age of three. Oral manifestations of this syndrome are the characteristics of the disorder and can help to make an early diagnosis.