JOURNAL OF DENTISTRY (SHIRAZ UNIVERSITY OF MEDICAL SCIENCES)
Year:2009 | Volume:10 | Issue:3 (24)|Papers Count:16

Statement of Problems: The extracted human teeth are commonly used in endodontic research and preclinical education. The Center for Disease Control (CDC) recommends sterilizing the extracted teeth by storing in 10% formalin for 2 weeks or autoclaving.Purpose: The purpose of this study was to determine the potential effect of storage in formalin or autoclaving of the extracted human teeth on the apical seal integrity of the obturated canals.Materials and Method: A total of 83 extracted single–rooted teeth, free of visible fracture, caries or large restoration or root canal treatment were collected, and temporarily stored in normal saline for no longer than 48 hours before categorizing them in experimental and control groups. The teeth were divided into three experimental groups of 25 each, and placed in 10% formalin for 2 weeks or autoclaved or immediately prepared. Eight teeth served as positive and negative controls. Preparations for all the teeth consisted of decornation, canal instrumentation by protaper system and obturation with lateral compaction technique. The teeth were immersed in India ink and cleared. Then the greatest extent of linear dye leakage was measured. Leakage measurements were evaluated for significant differences using ANOVA with Tukey's HSD Post Hoc analysis.Results: There was less dye leakage in the teeth stored in formalin as compared to autoclaved and freshly extracted teeth. No statistical significant differences in apical microleakage between the three experimental groups were observed (p>0.05).Conclusion: The results of this study revealed that storage of the extracted teeth for research and educational purpose in formalin or autoclaving had no effect on apical microleakage of the obturated teeth.

Statement of problem: The main purpose of root canal treatment is to eliminate microorganisms and their byproducts. The use of antimicrobial agents besides mechanical preparation is necessary to achieve this goal. On the other hand, calcium hydroxide is ineffective in Killing some resistant microorganisms. Purpose: The aim of this in vitro study was to compare the effectiveness of calcium hydroxide mixed with different vehicles (Distilled water, Sodium hypochlorite or Chlorhexidine) in disinfecting the root canal and dentin of the infected teeth.Materials and Method: After root canal preparation of 130 single rooted teeth, they were sterilized and randomly divided into three experimental (n= 40 in each group) and two control groups. Then, the specimens were experimentally infected with E. faecalis and C. albicans during a period of 21 days. The infected specimens were exposed to the pastes of calcium hydroxide mixed with distilled water solution, CHX or NaOCl. Antimicrobial assessment was performed at 24h, 48h, 1 week and 2 week (n=10 in each time interval). Microbial samples were obtained from the root canals before and after the experiment. Also, the dentin samples were obtained for evaluating dentin disinfection. The data were analyzed, using Two-way ANOVA test. Results: This study showed that there was no significant difference between the three intracanal medicaments and also between the four periods of time (p>0.05). However, the mixture of calcium hydroxide/distilled water did not completely eradicate E. faecalis from dentinal tubules at any period of time. Conclusion: According to the results of this study, calcium hydroxide mixed with CHX or NaOCl is better than calcium hydroxide mixed with distilled water for dentin disinfection in cases of persistent intracanal infection.

Statement of problem: Adverse surface interactions between one-bottle adhesives and self – cured composites may occur similarly with light-cured composites during the use of different modes of light activation. Purpose: This study examined the effect of different light activation modes of light-cured composite on the shear bond strength of 2 one-bottle adhesives with different acidity to the dentin.Materials and Method: This experimental study was performed on 110 extracted sound molars. Then, the teeth were randomly divided into 10 equal groups (n=11). One-Step plus (OS) and Prime & Bond NT (P&B NT) were used and followed by respective composite application in 5 light- activation modes of soft conventional, Soft-Start I (SSI), Soft-Start II (SSII), Pulse-Delay I (PDI), Pulse-Delay II (PDII). Then, shear bond strength (SBS) test was performed, using an Instron at 1 mm/min. The SBS was recorded in MPa. Statistical analysis included two way ANOVA with a significance level of 0.05.Results: The highest SBS (MPa) was shown in OS conventional group (19.62) and the lowest in P&B NT, PDII (5.43). In each group of 5 curing mode, mean SBS in P&B NT was significantly lower than that in OS as follows: In conventional; P&B NT (17.27) vs OS (19.82) in SSI; P&B NT (10.89) vs OS (13.09) in SSII; P&B NT (14.48) vs, OS (18.79) in PDI; P&B NT (5.93) vs OS (11.97) and in PDII; P&B NT (11.82) vs OS (16), ( p <0.001). In each of 2 adhesives, ranking of SBS from minimum to maximum was as follows: PDI<SSI<PDII<SSII<C. Two-paired comparisons of curing modes showed significant differences (p<0.05).Conclusion: The bond strength of P&B NT might be compromised by the higher acidity of this adhesive compared to OS during all of the curing modes especially PDI. The acidity of the adhesive showed the least effect on the conventional mode.

Statement of Problem: One of the most important goals of topical fluoride application is to prevent dental caries in children. General opinion reveals that topical fluoride has a negative effect on composite bond and adhesive materials to tooth; otherwise, it could be considered in pediatric dentistry. Purpose: The aim of this research was to evaluate and compare the effect of topical fluoride on shear bond strength of resin modified light cured glass ionomer to the etched and non-etched enamel of the primary tooth under different preparing conditions.Materials and Method: In this in-vitro experimental study, 108 primary canine teeth free of caries and crack were prepared in three main groups respectively: 1) immediately after using APF, 2) 24 hours after using APF, and 3) without using APF. Then, each main group was divided into three subgroups. The first subgroup received conditioner + GCFuii LC2, the second received GCFuii Lc2 + 3M phosphoric acid 35%, and the third one received composite 3Mz100 on the tooth surface. After thermocycling, the shear bond strength of the material on the teeth was measured by instron machine. Two- way ANOVA and Post hoc Bonferroni test was used for statistical analysis. Results: There were no statistically significant differences between the mean shear bond strength of the groups in which APF was used and those which did not receive topical fluoride (p >0.05). There was not a statistically significant difference, between the mean shear bond strength of GC Fuji LC2, using polyacrylic acid 20% and the same material using phosphoric acid 35%. However, there was a significant difference between the strength of shear bond of the two above materials and composite 3MZ100 (p <0.001). Conclusions: According to the results of this study, it can be concluded that 1- Application of APF, has little effect on reducing the strength of shear bond in GC Fuji LC2 and 3MZ100 composite. Moreover, 2- Using polyacrylic acid 20% and phosphoric acid 35% have similar effects on the strength of glass ionomer GC Fuji LC2 to the primary tooth enamel.

Statement of problem: Insufficient compressive strength of dental cements leads to crack formation and further complications such as unrestrained restorations, secondary caries and pulpal infections.Purpose: The aim of this study was to determine the compressive strength of two kinds of glass ionomer (GI) and zinc phosphate cements (ZPH).Materials and Method: In this study, the compressive strength of two kinds of zinc phosphate cements manufactured by GC (Elite cement 100) and Ariadent company was evaluated. Furthermore, two kinds of glass ionomer cements made by GC (Fuji I) and Ariadent company were examined. Five cylindrical samples were prepared according to ISO 9917 from each cement. After processing the samples in incubator and distilled water for 23 0.5 hours, they were examined in Instron mechanical tester. The data were analyzed by one way ANOVA and Tukey HSD methods.Results: The compressive strength of GI cements made by GC and Ariadent were 187±40 Mpa and 129±10 Mpa, respectively. Moreover, compressive strengths of ZPH cements made by GC and Ariadent were 83±21 and 123±21 Mpa. According to the results of one way ANOVA, GI cement made by GC had significantly higher compressive strength as compared to other cemens ( p <0.05). Tukey HSD test showed no significant difference between GI and ZPH cements manufactured by Ariadent (p >0.05).Conclusion: Glass ionomer cement manufactured by GC company had a significantly higher compressive strength compared to other cements. However, GI and ZPH cements made by Ariadent were acceptable according to ISO 9917 standards.

Statement of problem: Post-extraction dry socket is the most painful complication in oral surgery .It is not only time consuming for dentists and patients but also very expensive to treat.Purpose: The aim of this study was to evaluate the role of Irsha antibacterial mouth wash on reduction of dry socket prevalence in patients who referred to Tabriz Oral and Maxillofacial Surgery Department. Materials and Method: A quasi experimental study was conducted on 274 patients (146 in study group and 128 in the control group) with 300 sockets in their extracted teeth. Patients were randomly selected from those referred to Tabriz oral and maxillofacial clinic. Before extraction, the patients in the study group washed their mouth with Irsha mouth wash for 30 seconds to 1 minute and the operator rinsed the site of the extraction by gauze soaked with respective mouth wash. On 3 rd and 7 th days, they were called to fill the questionnaire. The patients with dry socket were invited to the oral and maxillofacial department and examined by an oral and maxillofacial surgeon. The collected data were statistically analyzed by Chi-Square test, using SPSS soft ware.Results: 2.5% of the patients in the study group and 10.5% in the control group had dry socket (p= 0.04), so there was a significant difference between the two groups. Influential factors in dry socket appearance such as smoking and oral hygiene condition were studied, showing a significant difference (p = 0.006 and 0.009, respectively). There was a significant difference between the extracted teeth with preapical lesions and those without any areas in their radiographs. Patients with poor oral hygiene showed more dry socket involvement than good oral hygienic group (p=0.006).Conclusion: Irsha antibacterial mouth wash like other antibacterial mouth washes can reduce dry socket prevalence. Bacterial accumulation and their virulence might be a major cause of the dry socket.

Statement of Problems: Numerous evidence indicates the deteriorating effects of obesity on body organs and its role in predisposition to systemic diseases such as diabetes. On the other hand, diabetes has been recognized as a risk factor for periodontal breakdown.Purpose: This study aimed to determine the relationship between obesity and periodontal diseases. The second aim was to clarify if periodontal diseases make the individuals prone to impaired glucose tolerance. Materials and Method: A total of 166 patients (age 35- 59 years) who sought dental care in Tabriz Dental Faculty were recruited in this study. Eighty three people had periodontitis in accordance with NHANES III index (test group) and the remaining who did not have periodontal disease served as the control group. The body weight (BW), height and waist circumference (WC) were measured in both of the study groups followed by fasting plasma glucose (FPG) and oral glucose tolerance test (OGTT). Data were analyzed by student t-test and Chi-Square followed by calculating the odds ratio and Spearman correlation.Results: All of the studied variables expressed a higher score in the test group than the control one (p < 0.05).Evaluation of the correlation of obesity (OB), overweigh (OW), WC, and impaired glucose tolerance (IGT) with periodontal disease severity, revealed the highest correlation between OB (r=1 and p<0.001) and the lowest between OW (r = 0.4 and p =0.07). Regarding the association of OB, WC and OW with IGT among women, the strongest association was found in OB (odds ratio, 6.5; 95% CI, 1.26- 23.6) and the weakest was in OW (odds ratio, 0.43; 95% CI, 0.07-2.6). These associations were similar among the males and the highest was between OB (odds ratio, 5; 95% CI, 0.82-19.41) VS. the weakest that was observed in OW (odds ratio, 0.39; 95% CI, 0.07-2.17). Conclusion: The association of obesity and periodontal disease is stronger than that with impaired glucose test. This may be attributed to different mechanisms involved in relationship between periodontal disease, obesity and diabetes.

Statement of Problem: In order to get ready for medical emergencies, sufficient scientific knowledge, suitable facilities and emergency drugs are necessary.Purpose: This study aimed to investigate the emergency facilities, drugs and the knowledge of dentists about emergency cases in dental offices of Kerman in 1386.Materials and Method: This is cross-sectional and descriptive study using questioners. Some active dental offices were selected and the questioners were given to them. The completed forms were gathered. The data were extracted and analyzed by t- test, fisher, x2, using SPSS13.5 statistical program.Results: In the present study, 101 dentists were enrolled. 25 dentists, (24.7%) had emergency cases in their office, and the most prevalent case was vasodepressor syncope. The mean knowledge of the dentist was 5.89±1.39. 76.2% of the dentists expressed that they ask the patients about their medical emergency history. This study shows that the knowledge and information of dentists enhance with an increase in working hours, and decrease with an increase usage and wok experience. Also, it is found that the most prevalent drugs used in dental office as emergency drugs were oxygen and nitroglycerine tablets.Conclusion: This study indicates that some emergency events take place in dental offices in Kerman as in many other countries but, unfortunately, there is not sufficient equipment and facilities to deal with these emergency cases. The present condition can be improved with teaching in universities, holding some educational workshops and preparation of pamphlets.

Statement of Problems: The knowledge regarding risk factors and primary signs of oral cancer in general population can help them to avoid the risk factors of cancer and their timely referral to physicians. Purpose: The aim of this study was to survey the adult knowledge about the risk factors and signs of oral cancer in Kerman city in 2007.Materials and Method: In this descriptive cross-sectional study, 723 adults who referred to Kerman Dental School and clinics were enrolled. The data were collected using a questionnaire. The data were analyzed by ANOVA and t- test.Results: The results of this study showed that the mean knowledge about the risk factors and signs of oral cancer were (6.04±2.31 from 15) and (2±1.3 from 6), respectively. There was only a significant difference between knowledge about risk factory of oral cancer and the education of the participants.Conclusion: Low level of knowledge of adult people regarding both risk factors and signs of oral cancer stresses the need to more efforts made about the above-mentioned issues by media.

Statement of problem: Orofacial tumors are a heterogeneous group of lesions having various histological types and clinical behavior. The prevalence and clinical behavior of some pathologic lesions is different in various populations.Purpose: The aim of this study was to determine the type and distribution of orofacial tumors among patients referred to the Oral Pathology Departments of Shiraz Dental School and Chamran Hospital in Iran. Materials and Method: In this retrospective case series study, data on the type, age, sex and site of tumors in 2343 patients with orofacial lesions in the period from 1991-2008 were collected and analyzed, using SPSS13. Results: In this study, 300 (12.8%) tumors were found among the subjects. The most common types of benign and malignant tumors were odontoma and langerhans cell histiocytosis in children and adolescents, and unicystic ameloblastoma and squamous cell carcinoma in the adults, respectively. The most common site of tumors in soft tissue was gingiva and in the jaws it was the posterior part of the mandible.Conclusion: The observed differences in the tumor type and distribution in this study compared with the previous studies, in addition to design and methods of the study, may be attributed to genetic and geographic variations in the population. Therefore, more extensive investigations are recommended to achieve more information about these lesions which can be used for assessment of patients.

Statement of problem: Periapical surgery has been performed to remove irritant factors and seal the end of the root. So, selections of retrograde filling materials which can produce hermetic seal and are easily available with reasonable prices seem to be necessary.Purpose: The aim of this in-vitro study was to compare the sealing ability of Pro Root MTA, Root- MTA and Portland cement.Materials and Method: In this experimental in-vitro study, 40 intact mandibular first premolar teeth were selected and cut from the site of cemento-enamel junction (CEJ). The canals were prepared using step back method and obturated with Gutta-Percha and sealer by lateral condensation technique. The 3 mm of the apical portion of the roots were cut with a 45 angle to the long axis of the teeth. Thirty six teeth were divided into three experimental groups and the 4 remaining teeth were considered as control groups. Cavities randomly with 3 mm depth were prepared in the apical of the canals by a ½ round bar, and in the experimental groups they were filled with pro-root MTA, root MTA and/or Portland cement. The surfaces of the roots were covered by nail polish. After incubations, the teeth were kept in %2 methylen blue solution for 24 hours. Then, the teeth were cut longitudinally and the depths of color penetration were evaluated by a stereo microscope. The data were analyzed using one-way ANOVA and Mann-Whitney U test.Results: In the positive control group, the dye had penetrated the total cavity; in the negative control group, microleakage was not found. There was no significant differences between the Pro Root MTA and Root MTA (p>0.05), but Pro Root MTA and Root MTA had significant differences with Portland cement (p<0.05). Pro-root MTA had the lowest apical microleakage followed by root MTA and Portland cement respectively. Conclusion: Considering the results of this study, Portland cement cannot be replaced with Pro-root MTA in retrograde fillings, but using Root MTA as a substitute for Pro Root MTA needs more investigations.

The term calcifying odontogenic cyst was first used by Gorlin in 1962 to describe a new cystic entity with a peculiar pathogenesis and histologic feature. Other odontogenic tumors such as ameloblastoma, odontoma, ameloblastic fibroma, ameloblastic fibroodontoma, odontoameloblastoma, pindborg's tumor, and adenomatoid odontogenic tumor may seldom be associated with this lesion. This paper describes the case of a 16-year-old male with a remarkable combination of two entities. The lesion associated with an impacted canine tooth was detected at the mandibular left side, producing an extensive expansion of buccal cortical plate on panoramic view. During the operation, enucleation of the cyst was performed and the impacted canine tooth was extracted. The histologic specimen revealed the diagnosis of an adenomatoid odontogenic tumor (AOT) in a calcifying odontogenic cyst (COC).