Journal of Dentistry
Year:2007 | Volume:7 | Issue:3-4 (13)|Papers Count:17

Statement of problem: "Power Bleaching" which is a new an in-office whitening technique with a combination of a whitening agent (peroxide) and an auxiliary (plasma-Arch light), has been claimed to be an effective and fast method in tooth bleaching. What is more important in using this method is the maintenance of the pulp health after tooth whitening.Purpose: The aim of this study was to evaluate the human pulpal response after bleaching with H2O2 38% and plasma-Arc light.Materials and method: Eighty seven sound first premolars from 27 patients were selected and divided into 3 groups of 29, based on the time intervals of histologic evaluation. In each group 9 teeth were considered as a control. Vitality tests were done before bleaching (base line) and in four intervals of 2, 7, 30 and 60 days, but histologic evaluation was performed in three intervals 2, 7 and 60 days. Immediately after extraction, apical one third of the roots were sectioned off and each specimen was placed in 10% buffered formalin solution for pulpal fixation. EDTA was used for decalcification and sections were prepared from each specimen and stained with H&E and subsequently assessed microscopically for the following criteria: Irregularities in the odontoblastic layer, the presence of inflammatory cell, vasodilatation and pulpal fibrosis. Data was analyzed using Friedman test and Wilcoxon test (a= 0.05). Results: There were significant differences between the 2 and 60 days groups and between 7 and 60 days groups with respect to inflammatory responses and vasodilatation (p<0.05).Comparison of the control and experimental groups of the 2 and 7 days revealed statistically significant differences in inflammation and vasodilatation (p<0.05). No patient had experienced sensitivity, after different bleaching periods.Conclusion: Bleaching of teeth with H2O2 38% and plasma-Arc light might cause slight to moderate pulp reactions after 2 and 7 days confined to the coronal pulp. However, the observed histological changes did not affect the overall health of the pulp tissue permanently.

Statement of problem: Studies have shown the effect of sealers used with master cones in order to gain better apical multi dimensional sealing. This goal is considered to be effective in treatment prognosis and blocking micro-organisms and limiting their activities. Applicable sealers should have advantages such as little dissolution and proper adaptation to periapical tissue. Calcium phosphate and hydroxyapatite are compounds that have shown significant effect in recovery of osseous lesions.Purpose: The aim of this study was to apply a mixture of these materials as sealer, named Apatite Root Sealer, with gutta percha in root canals and compare its micro leakage with AH26 sealer.Materials and method: In this experimental study 26 extracted single-root human adult teeth, with same size and without curve were selected. The apical third of roots were prepared by step-back technique and Race rotary files (6%) up to MAF# 40 and the coronal two thirds were prepared by gates gliddens. The canals were irrigated with sodium hypochlorite 5.25%. The teeth were divided in two test groups of 10 and two control groups of three teeth. Group A: Canals were filled with gutta percha & Apatite Root Sealer. Group B: Canals were filled with gutta percha & AH26 sealer.The access cavities were sealed with Glass ionomer and then samples were placed in incubator at 37°C and 100% humidity for about 48 hours. After sealing the roots with two layers of nail polish and sticky wax except for the two mm of apical area, the teeth were placed in silver nitrate 50% for six hours and then rinsed and exposed to florescent light before floating in developing solution for about two hours. Specimens were sectioned longitudinally from buccal to lingual and examined under a stereomicroscope by 0.1 mm accuracy. The dye penetration level was measured and analyzed using T-student statistical test.Results: Measuring the samples showed that dye penetration in Apatite root sealer group was more than AH26 group, which was significantly comparative (p<0.001).Conclusion: Since the resin-based sealer (AH26) was more trustworthy and effective in achieving apical seal in comparison to the Apatite root sealer, its application is more recommended.

Statement of problem: Salivary gland tumors comprise a large groupe of oral cavity lesions. Ductal and myoepithelial cells are introduced as original cells in salivary gland tumors .The histogenesis of salivary gland tumors are controversial.Purpose: With considering the role of s-100 protein in demonstration of myoepithelial cells, the purpose of this study was the determination of immunoreactivity pattern and distribution of myoepithelial cells in PA, ACC and MEC.Materials and method: Formalin- fixed paraffin- embedded from 5 PAs, 5 ACCs and 5 MECs were studied immunohistochemically with employing S-100 protein. The S-100 protein positive cells were counted and mean score of Labeling Index (LI) were achieved. The immunoreactivity and staining pattern of each tumor were stablished. Lack of bleeding and necrosis was considered as inclusion criteria.Result: 1) In PA: The plasmacytoid and some of ductal cells were stained positive (LI=0.34). The immunoassaying reaction was moderate to severe.2) In ACC: S-100 protein Immunoreactivity was negative (LI=0).3) In MEC: The small numbers of epithelial cells were stained. Since, the stained epithelial cells were lesser than 5%, the MECs was considered negative.Conclusion: Based on this study, the myoepithelial cells do not comprises the main cellular part in ACC and MEC.

Statement of problem: Perforation is one of the most important problems which may occur during root canal therapy. To repair the perforation and to cut the relation of the root with the tissue of its peripheral environment, materials with adequate sealing ability and suitable price are needed.Purpose: The aim of this study was to survey the micro leakage of the three materials in the restoration of lateral perforations in the roots of the teeth.Materials and method: In this experimental study, 54 intact molar teeth were selected and assigned randomly to three groups. Canals were prepared with step back technique and perforations were made at the apical third of the roots. The cavities were restored with MTA, Root MTA and Portland Cements type 1. The positive control group was subjected to perforation but no perforations were made in the negative control group. The teeth were covered with two layers of nail varnish restoring in 2% fushin solution for 24 hours after incubation. The teeth were sectioned and their leakage was measured by stereomicroscope. The records were analyzed by one- way ANOVA and LSD (Least Square Differences) test.Results: In the positive group dye was completely entered in all perforation areas while no leakage was observed in the negative group. The statistical test showed no significant difference between MTA and Root MTA groups in terms of leakage (p>0.05). But MTA and Root MTA had significant differences with Portland cement (p<0.0001).Conclusion: Considering the results of this study, Root MTA may be considered as a substitute for Pro Root MTA in root canal treatment; however, using Portland type I cement needs more investigations.

Statement of problem: The sealing ability of different endodontic sealers has been evaluated using micro-leakage tests and/or measuring their bond strength (adhesion) to dentin and gutta percha. However, the micro-leakage studies do not determine the location of the micro-leakage. Therefore, to determine whether the micro-leakage occurs in the dentin-sealer or the gutta percha- sealer interfaces, the bond strength studies are required.Purpose: The purpose of the present study was to measure the bond strength of AH26 and Dorifill to dentin and gutta percha and to compare their relationship with their apical microleakage values using electrochemical test.Materials and method: In this laboratory study, to evaluate the tensile strength of AH26 and Dorfill, the dentinal coronal surface of the twenty four extracted maxillary and mandibular first and second molars were used. Twenty four disk shape specimens of the gutta-percha were prepared. Two groups of sealers (AH26, Dorifill) were placed within the aluminum customized cylinders (n=48) and stabilized on the dentin and gutta-percha. The tensile strength of each sealer with dentin; and gutta- percha were measured separately by a universal testing machine (zwick) in four groups (12 samples in each groups). The data were analyzed using independent samples t-test. To evaluate the sealers' apical leakages using electrochemical method, 36 maxillary and mandibular canines were used. The selected teeth randomly divided into 2 groups (16 sample in each group) and 4 teeth as control. After canal preparation, each group was filled with one of the sealers and gutta-percha using lateral condensation method. Measurment of current flow through the test system were recorded as a voltage drop across the 100-ohm resistance by a digital multimiter every 72 hour. The data were analyzed using Mann- Whitney test. Results: the bond strength of AH26 to both dentin and gutta-percha was significantly stronger than Dorifill. AH26 had a significantly lower magnitude of apical microleakage than DorifillConclusion: the results of this study showed a direct relation between sealers' bond strength to dentin and gutta-percha with their resistance to apical micro-leakages.

Statement of problem: Evaluation of facial skeletal trauma is based on clinical and radiographic examinations. For many years, conventional radiographs have been used in diagnosis of fractures. Today, advanced techniques such as CT and 3D-CT gradually are used as complementary techniques for conventional methods. Panoramic radiography is one of these conventional radiographs which cover maxilla, mandible, zygoma and sometimes inferior orbital rims. "Water's views" is the specialized radiographic technique of zygomatic bone and orbital rims in diagnosis of facial fracture.Purpose: To determine the agreement of panoramic radiographs with water's views in detection of zygomatic complex and inferior orbital rim fractures.Materials and method: In this descriptive-analytical study, 58 panoramics and water's views of patients with maxillofacial trauma were selected. These radiographs were coded and an experienced maxillofacial radiologist expressed about the presence or absence of fracture in maxillary process of zygomatic bone, inferior orbital rims, temporal process of zygoma, lateral wall of maxillary sinuses and zygomatic arch.The patients' demographic information was gathered by SPSS version 11.5. Kappa analysis test was used for calculation of the agreement rate between two radiographs Pvalues < 0/05 was regarded as significant.Results: Water's and panoramic views had the most agreement rate of very good to ideal level in diagnosis of fracture of maxillary process of zygoma (p<0.001, K=0.76).The agreement rate in diagnosis of fracture of temporal process of zygoma, inferior orbital rim and lateral wall of maxillary sinuses was in medium to good level but the agreement rate in diagnosis of zygomatic arch fracture was the least.Conclusion: According to the results of this study, the panoramic findings must be taken seriously in diagnosis of the fracture of maxillary process of zygoma and inferior orbital rim. The importance of this view must be considered in diagnosis of mid facial fracture especially in traumatic patients due to widespread coverage of facial bones.

Statement of problem: Despite the various methods used to initiate the polymerization of resin, the conversion of monomers to polymers is not complete and some unreacted monomers are left in the polymer that is leachable into saliva. Substance leached from resin can cause adverse reactions in the oral mucosa adjacent to the denture.Aim: The aim of this study was the comparison of cellular toxicity of Iranian and non Iranian self cure acryl on mouse L929 gingival fibroblasts. Materials and method: Three types of acryl including Trim acryl (poly vinyl Ethyl Methacrylate), Duralay acryl (poly methyl Methacrylate) and Acropars acryl (poly methyl methacrylate) were used. A total of 90 rings (30 for each type) with predetermined sizes were prepared. Suspension of fibroblasts with acrylic rings was put in 24-wells culture plates and a culture media containing RPMI-1640 environment plus antibiotics and 10% FBS were added. The plates were incubated in the Co2 incubator and after one hour, 24 hours and seven days they were checked for cytotoxicity by MTT test and secretion of IL-6 by ELISA technique. Two-way ANOVA, Kruskal-wallis and Mann-Whitney U tests were used for data analysis.Results: Significant differences were found in the biocompatibility of experimental acryl, Trim and Duralay (p<0.05) Acropars and Duralay (p<0.01) and Acropars and Trim (p<0.001), among studied time intervals. No statistically significant difference was seen in the production ofIL-6 among these acryl (p=0.120). Least cytotoxicity was seen at interval of 24 hours with significant statistically difference between one hour and one week time intervals (p<0.001).Conclusion: This study showed that the acryl having methyl methacrylate (Acropars and duralay) have greater toxic effects on fibroblasts; although the toxic effects of Acropars were more than Duralay. The least cytotoxicity was seen in Trim which has vinylethyl methacrylate. There was no difference among studied acryl on induction of IL-6.

Statement of problem: Root fracture of permanent teeth caused by injury are relatively rare, occurred in 0/5-7 percent of dental injuries cases. Generally, final diagnosis is based on the radiographic features of a fracture .line/ lines, and mobility of the coronal segments of the teeth. In the recent years, digital radiography with different types of receptors has become available. These receptors have some advantages, in which the greatest is dose reduction.Purpose: The aim of this study was to compare the detectional accuracy of PSP receptor with dental film F in the diagnosis of root facture.Materials and method: In this in-vitro study 162 extracted human teeth were selected and parallel periapical radiographs of teeth were taken with two different receptors (film-F, PSP) under a standard condition. The presence or absence of root fracture was evaluated by two observers according to 2 points confidence scale. The actual status of each root of the tooth was determined by sable-seek staining. Sensitivity and specificity of the imaging modalities were calculated and the observer responses were analyzed with Mc-Nemar and kappa test.Results: The sensitivity value of F-speed film and PSP receptor were 80 and 77.5% respectively, while the specificity values were 83.5 and 87% respectively. The difference in detecting root fracture between the test groups was not statistically significant.Conclusion: Although, there is no statistically significant differences between evaluated imaging modalities in root fracture detection, because of reduced exposure in digital radiography relative to conventional film, it seems logical if the conventional radiographic films will be replaced by digital system in root fracture detection.

Statement of Problem: Oral Mucositis (OM) is a frequent and well-known side effect of cancer chemotherapy as well as head and neck radiation therapy. Considering the proposed critical role of pro-inflammatory cytokines and an important cellular transcription factor (Nuclear Factor-kappa B) in pathogenesis of OM, an animal study was planned to evaluate the possible effects from powerful inhibition of the above-mentioned factors on OM.Purpose: Evaluation of the effects of systemic dexamethasone (DEX) premeditation on the course and severity of a short-term chemotherapy-induced OM in an animal model.Materials and method: In this trial, 75 male adult golden hamsters were recruited by random division to three groups as following: Group A: Received neither chemotherapy nor DEX premedication. Group B: Received chemotherapy and also normal saline as premeditation. Group C: Received chemotherapy and also DEX as premedication in specified dosages for three sub-groups, each with 15 animals.Chemotherapy was administered by once daily injections of 5-Fluorouracil on the days 1 and 2 of the experiment. Premeditations implied either as normal saline or DEX, were administered as once daily injections at the same time of days 1 to 9; those of the days 1 and 2 were followed one hour later by 5-FU injections. On the fourth day of the experiment, the cheek pouch mucosa of all animals was irritated by scratches of sterile needle tip to potentiate OM. On the days 6, 9 and 16, the cheek pouches were examined clinically and histopathologically for determination of definite macroscopic and microscopic scores in a blind fashion. Moreover, on the day 9, blood sampling for culture as well as histopathologic analysis for oral candidiasis were carried out respectively on randomized subsets of 2 and 5 animals per each group. The data were analyzed by Kruskal-Wallis test. Results: Comparison of macroscopic as well as microscopic scores among different groups, showed prominent protective role from DEX premeditation at high and moderate dosages, seen clinically as less severe forms of OM. The most important negative outcome from DEX premedication was mortality in a number of animals, with the most occurring in the high-dosage subgroup.Conclusion: It seems that among the three dosages of DEX premedication in this trial, the moderate dose (0.1 mg/kg) showed good results, both in terms of less mortality and also remarkable effect on reducing the severity of OM.

Statement of Problem: Formocresol has been considered as a popular pulpotomy medicament in the primary dentition for the past 60 years. However, concerns have been raised on its potential toxicity and mutagen city during recent years. Therefore, many alternatives have been recommended over the years for form ocresolas pulpot omyagents in primary teeth.Purpose: The aim of this study was to evaluate the clinical and radiographic success rates of electro surgery as a pulptomy technique in pulpotomized primary molar teeth.Materials and method: Forty primary molar teeth were randomly selected and treated using needle shape electrode in an electrosurgical unit as the pulpotomy technique. All teeth were treated in one treatment session. Patients were placed on a recall program and were evaluated clinically and radio graphically after 6-12 month follow up period. Any evidences of pain, fistula, swelling, abnormal mobility, furcation radiolucency or pathologic root resorption were considered as criteria for failure of treatment.Results: After 6-12 month observation period, the clinical success rate was found to be 100% while the radiographic success rate was 84.2%. The overall success rate for this type of treatment showed to be 84.2%. Conclusion: Since electro surgery is a nonpharmacologic, easy to use, rapid and effective technique, it may be recommended as a suitable alternative for form cresol pulpotomy in primary molar teeth.

Statement of problem: Hyperactive gag reflexes in some dental patients may lead to difficulties In the treatment processes. Various methods have been introduced for control of gag reflex in dentistry.Purpose: The aim of this study was to evaluate the effect of inhalation sedation for gag reflex control in patients with hyperactive gag reflexes and improving operation condition during dental treatment.Materials and method: In this clinical trial study 14 healthy adult patients with tow times failure in dental treatment due to the hyperactive gag reflexes were selected for treatment of posterior mandibular teeth. For all patients, treatment was performed under inhalation sedation with 50% N2O and 50% O2. Severity of gag reflexes and operation conditions was evaluated and results were analyzed using Spearman, Mann Whitney and Wilcoxon tests.Results: Of 14 patients under study, 4 patients were men (28.6%) and 10 patients were women (71.4%). Gag reflex during operation was suppressed in 11 patients (77.8%) and "it was active in only three patients (21.4). Dental treatment was performed easily in nine patients (64.2%), while in three patients (21.4%) it was done with difficulty and in two patients (14.3%) no treatment was performed due to hyperactive gag reflex. Complications were not 0bserved during treatment.Conclusion: For reducing gag reflexes and improving the operations condition in patients with severe gag reflexes it is possible to use inhalation sedation (N2O and O2) which is easy to use and safe. In case, this method is not sufficient, treatment should be performed under general anesthesia.

Statement of problem: The electric pulp test (EPT) is an important diagnostic aid in evaluation of pulpal vitality. It was postulated that premeditation with analgesics can decrease tooth sensitivity to electric stimulation.Purpose: The purpose of this study was to evaluate the effect of premeditation with ibuprofen on the responses of vital central teeth to electric pulp tester.Materials and method: This clinical trial study was performed on 88 intact maxillary central and lateral incisors. After taking medical and dental histories and clinical examinations, electric pulp testing was done using tooth paste as conducting medium and the results were recorded. Afterwards, each subject received a 400mg ibuprofen tablet and one hour later, electric pulp testing was conducted again. The data were statistically analyzed using t-test to compare pre- and post-medication records.Results: The mean EPT scale of teeth before ibuprofen administration was 2.5, whereas after drug administration the mean EPT scale of the teeth was 2.7. Statistical analysis showed significant differences.Conclusion: This investigation showed that, although ibuprofen decreased the tooth sensitivity to electrical stimulation, but with proper attention in using pulp tester, it could still be a valuable aid in clinical practice for patient's receiving Ibuprofen.

Statement of problem: Many risk factors cause progression of peritonitis. Smoking is one of these factors and due to increasing rate of smokers, there is need to study more about the effect of smoking on periodontal indicators.Purpose: The aim of this study was clinical evaluation .of smoking effects on periodontal tissues in referring patients to oral medicine and periodontics department in Tabriz dental faculty.Materials and method: This study was an analytical, cross-sectional study. Sample size consisted of one hundred patients with chronic periodontitis. Of these patients, 50 smoker patients (34 Heavy smokers and 16 Light smokers) entered into case group and 50 non-smoker patients entered into control group. After ensuring age matching between smokers and non-smokers, periodontal measurements such as clinical probing depth (CPD), gingival recession (OR), clinical attachment level (CAL), tooth mobility (TM) and bleeding on Probing (BOP) were obtained and recorded in special questionnaires. Data analysis was performed by SPSS soft ware and Tukey and Pearson tests.Results: Clinical probing depth, gingival recession, clinical attachment loss and tooth mobility increased significantly in Heavy smokers compared with non-smokers and Light smokers (p<0.05), while no statistically significant differences were found between non- smoker and light smoker groups.Considering bleeding on probing, there was declining trend in BOP in Heavy smokers compared with non-smokers and Light smokers (p=0.00). There was not significant differences upon the effect of cigarette consumption (based on pack years) in the mentioned indices (p>0.05) between the two groups.Conclusion: Based on the results of this study which showed an increasing rate of intensity in periodontal indicators in smokers group compared with non-smoker, specific programs to increase public awareness on the effect of smoking should be recommended.

Statement of problem: Bonding agents are one of the most important materials in adhesive dentistry. Sixth generation bondings have more simple application than fifth generation, but despite this, it has been addressed by some articles that adhesive strength of sixth generation gradually decreases over time. Purpose: The aim of this study was to compare the shear bond strength of a resin composite with application of two bonding agents (fifth and sixth generation) after three months storage in normal saline.Materials and method: This in vitro study was conducted on 40 anterior bovine teeth. After complete removal of enamels, the samples were randomly divided into four groups based on the use of acid etch technique and the type of bonding agents (Excite or Prompt L-pop).After applying Z250 composite resin, the samples were immersed in normal saline for 90 days and then were thermocycled and subjected to shear bond testing with Dartec universal testing machine. Statistical analysis was performed using one-way ANOVA and Tukey's test.Results: In non-etched groups, Prompt L-pop showed significant higher bond strength than Exite, but in etched groups Excite had significantly higher bond strength (p<0.005). There were no significant differences in Prompt L-pop subgroups with or without etching meanwhile in Excite subgroups, significant differences were found.Conclusion: The use of Excite with acid etching technique provides more reliable bonding than Prompt L-pop to dentin.

Statement of Problem: During treatment with functional appliance in patient with class II division I malocclusion, mandible is postured inferiorly and anteriorly. Considering the relation between mandible with tongue and oropharynx space, functional appliance therapy can alter the tongue position and oropharynx space.Purpose: This study aimed to determine the changes of oropharynx space and posterior surface of the tongue position following treatment with Farmand functional appliances in patients with class II division I malocclusions.Materials and method: In this clinical trial study, 28 pre and post treatment cephalometric radiographs of patients with class II division I malocclusions were investigated. The age rang of females was 10-13 years and in males it was 11-14 years. The patients were treated by Farmand functional applicne for 11 months. McNamara analysis and some linear variables were used to determine the positional changes of tongue and oropharynx space.Paired-t test was used to compare the pre and post treatment differences of mean values. Variance analysis was used to compare the growth patterns of the patients.Results: Tongue moved significantly forward (p<0.001) but non-significantly downward. Oropharynx space increased significantly in sagittal dimension (p<0.001). There was a significant correlation between decrease of ANB angle with forward movement of tongue (p<0.05) as well as with the increase in extent of oropharynx space in the sagittal dimension (p<0.05).Conclusion: Treatment with Farmand functional appliance showed significant alteration in tongue position and as a result, increased the extent of oropharyngeal space.

Statement of problem: Increasing demands for health care services on one hand, and limited resources on the other hand brings about pressure over governments to find out a mechanism for fair and appropriate distribution of resources. Economic analysis is one of the appropriate tools for policy making on this priority.Purpose: The objective of this study was to assess capital and consumption expenditure of Oral Health Units of Health Care Centers in Fars province and its effectiveness on oral health indices.Materials and method: The data were collected by statistical forms in urban and rural Health Care Centers which were sent to Provincial Health Care Centers every 3 months from 2001 to 2003.Results: Oral Health Unit service expenses had been 6,871,471,160 Rials in 2001, 6,243,026,540 Rials in 2002 and 7,009,570,880 Rials in 2003 respectively. Income/cost ratio was 20% in 2001 and it was 25% and 26% in 2002 and 2003 respectively. In spite of these high expenses, the oral health statues of 6-12 year old children did not improve during the survey period.Conclusion: Regarding the low tariff of dentistry services and also subsidiary payment to target groups, the Oral Health Unit expenses are always more than its income. These costs had no effect on oral health indices (dmft, DMFT) in Fars province.