Journal of Dental School
Volume:22 Issue: 2, 2004

The aim of this research is assessment off radiation protection in Shahid Beheshti dental offices. Method & Material: This descriptive study was performed in 200 dental offices in 7 parts of Tehran under supervision of Shahid Beheshti University which were selected randomly in 2002. From these offices, 94% didn’t use Lead shielded wall, 75.5% didn’t use Lead partition, and in all of them distance between practitioner and x-ray unit was acceptable, in 1% rectangular collimator was used. The knowledge of dentists about radiation protection rules and methods were very poor and it is essential to emphasize on the radiation effects and x - ray risk and radiation protection guidelines in continuing education lectures.

Regional odonto dysplasia (ROD) is an unusual nonhereditary of teeth with significantly clinical and radiographic features. Affected teeth usually remain unerupted or semi-erupted with a discolaration and irregular shape. Radiographically these teeth have a large pulp chamber and thin layer of enamel and dentin with similar density. This article is introducing a female patient who was affected by regional odonto dysplasia (ROD) (a developmental abnormality) and treatment of this patient. Case Report: This patient is a ten-year-old girl was referred to us with unerupted anterior maxillary teeth. Her parents stated that the CBA A teeth were extracted at the age of 3 for infection. At the first appointment the erupted left maxillary central tooth had malformation, discoloration and a related fistula with infected drainage. The 321 teeth germs were not erupted. Due to surgical procedure the left permanent incisor (1) was extracted and right permanent central, lateral and canine (321) were enucleated, and appropriate prosthetic treatment was performed for patient after a while.

The aim of this study was to investigate the mechanical properties of two newly introduced glass–ionomers (Iono cid – F and Iono Gem LC) to the market. Two well-known glass ionomer cements (Fuji II and Fuji II LC) were used for comparison. Methods & Materials: Fifteen cylindrical specimens were made from each material and were tested under compression at 1 hours, 24 hours and 1week after preparation. Another fifteen specimens having dimensions of (2x2x25mm) were made to study the flexural strength of the materials at the same intervals. One-way ANOVA and Scheffe tests were used to determine any statistically significant differences. The results indicated that Fuji II LC showed higher compressive and flexural strength at 1 hour and 1 week. Two new glass-ionomer cements exhibited compressive and flexural strength less than that of the two other glass-ionomers tested. It was concluded that the new glass-ionomers distributed are significantly weaker and might show less satisfactory clinical performance.

Several clinical parameters are used in epidemiological surveys of periodontal diseases as well as in treatment planning for periodontal patients. The CPTIN index was originally introduced to determine the periodontal treatment needs in communities. Since periodontal evaluation is always neglected in dental offices and the convenience of using CPITN, this index was compared with clinical attachment level, pocket depth, bleeding on probing and bone loss in 25 patients. Method & Material: Using a WHO 612 CPITN probe measurements was carried out and pocket depth was measured by means of a pressure sensitive probe with a constant force of 25 g. Bone loss was measured from patients P.A. radiographs. Spearman rank correlation test showed a strong significant correlation between CPITN and pocket depth (r=0.82, P<0.0001). Since, pocket depth is an important factor in treatment planning, this finding beside the convenience of CPITN use in dental clinics, this index is suggested for clinical use.

The purpose of this study was to report our experience in the diagnosis, surgical treatment and follow up of 27 Iranian patients. Method & Materials: A retrospective analysis was conducted of odontogenic keratocyst that were diagnosed and treated between 1991-2002.Clinical and histologic data were complied from the patient records and pathologic reports. Including recurrences and syndromic types, the material comprises 37 OKCs. The man: woman ratio was 2.375:1 and most of the patients belonged to the age groups 20-29 (%29.7) and 10-19(%18.5). %83.8 of the OKCs were localized in the mandible. The most common site was the third molar, angle and Ascending ramus area. The most frequent clinical manifestation at first admission were swelling (%77.7), pain (%63), purulent discharge (%48.1) and neurologic involvement (%14.8). Radiographic impressions included unilocular pattern (%68.8) and multilocular pattern (%31.2). The diagnosis of Gorlin's syndrome was established in two patients (%7.5). Recurrences were observed in 5 patients and the mean time interval between the primary operation and the first recurrence was 3 years. Half of the cases were treated with enucleation and corettage,%36 with enucleation and peripheral ostectomy,%8 with marsupialization and %5 with partial resection.Parakeratosis and ortho-and parakeratosis was observed in %94.6of the cases and orthokeratosis in %5.4.Malignancy was observed in one case. In our study, most features of OKC are consistent with those previously reported.

There is an increasing of prevalence of chronic obstructive pulmonary diseases (COPD). A lot of researches have shown the relation between periodontal and some kinds of systemic disease. To determine the relation between periodontal disease and COPD this research was performed on patients in Labafinejad hospital and their match control group at 2001-2002. Method & Material: In this case-control study, test group consisted of patients with diagnosed COPD and control group was selected same as test group except for having COPD. Periodontal examination was done which was included: Pocket Depth measurement (PD), Bleeding on Probing (BoP), Probing Attachment Loss (PAL) and plaque index (Loe and Silness). By use of statistical analysis, the above measurements were interpreted. This study was done on 130 attendants totally, 65 persons in each group. The group (case and control) were matched based on age, gender, smoking, socio-economic condition. In the control group, 9.2% and in the test group 29.2.% had PD>3mm (P<0.05) that means COPD patients were 3.4 times more at risk of PD>3mm. In the control and test group, BOP were 49.5 ± 11.7 and 63.5 ± 15.2 (P<0.0001) respectively and COPD patients are 1.8 times more at risk of gingival bleeding in comparison to the control group. PAL>2mm in the control and test group were 61.5% and 80% respectively (P<0.02) that means in COPD patients there is 2.5 times more risk to have PAL>2mm than the control group. Moderate and advanced PI in the control and test group were 24.6% and 44.6% (P<0.02) respectively which shows COPD patients are 2.47 times more at risk of moderate and advance PI. There is a direct relation between periodontal disease and COPD. We recommend an experimental study to show the efficacy of periodontal treatment on progression and prognosis of COPD.

The most detailed information about neural activity comes from intracellular recording. Not only this technique shows the pattern of neural action potential, but it also records the cellular events which give rise to the action potential, including variations in the resting potential, changes in cellular resistance and synaptic potentials. Using this method with manipulation of the composition of the bathing solution (changing ionic concentrations or adding drugs) the ionic mechanisms responsible for these potentials can be identified. It is also possible to investigate the mechanisms of actions of drugs such as dental sealers on neuronal excitability. In the present study, intracellular recording technique has been introduced in dental materials research as a valuable method to determine the neurotoxicity of endodontic sealers on neuronal cells.

Amalgam restorations often tarnish and corrode in the oral environment. The degree of tarnish and the resulting discoloration appear to be dependent on the parameters such as oral environment, oral hygiene, and the particular alloy employed and clinical procedures. The aim of this research was to evaluate and compare the effect of clinical procedures such as carving, carving-burnishing and carving-burnishing-polishing on the tarnish and corrosion behavior of four brand dental amalgams. Method & Materials: Four different type of commercial amalgam alloy powders with different powders with various particles shape (lathe cut, spherical, spheroids) namely Sybraloy (Sy), Cinalux (CL), Oralloy (Or) and cinaalloy (Ca) were studied. A special mold was used to prepare the samples of each type of commercial amalgams. Twenty-one samples of each type of amalgams were prepared. After trituration and condensation, the samples of each type of amalgams were divided into three groups and each group was finished by using one of three procedures carving, carving-burnishing, carving-burnishing-polishing. Electrochemical potentiodynamic tests were performed at a temperature of 37±1 °C in order to determine and compare the corrosion behavior of dental amalgams, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current densities values of three different groups of each type of commercial amalgam (P<0.05). The polished group of each type of commercial amalgams possesses the lowest corrosion current density and the carved group shows the highest corrosion current density (the lowest corrosion resistance). This trend was not affected by the brand and chemical composition of commercial amalgams. The polished Sybraloy amalgam possesses the highest corrosion resistance between four types of polished amalgams and the polished Cinaaloy amalgam showed the lowest corrosion resistance. The similar trend was observed in carved group and carved-burnished group of four types of amalgams. It was concluded that the clinical operations and procedures could influence the tarnish and corrosion behavior of high copper dental amalgams. Polishing procedure increases the corrosion resistance of high copper dental amalgams and is more effective on the corrosion behavior of dental amalgams, which are less corrosion resistant in compare with the dental amalgams that are more corrosion resistant.

The aim of this study was to determine the maximum amount of acute inflammation in the periapical region of cat's preinfected canine teeth, following instrumentation of root canals with standard Profile (performed with double-Z method), Step-Back (with K-type file) and Crown-Down (with Nitiflex file) preparation techniques. Method & Material: 30 mature and healthy cats were selected and after cutting the crown of 3 of its canine teeth and removing the pulp and opening a path from the oral cavity to the periapical region (with over-instrumenting the canal with small-sized files), 48 hours later, the crownless canine teeth were randomly instrumented with Standard Profile, Crown-Down (using Nitiflex file) and Step-Back (using K-type file) techniques and the fourth tooth was left intact as the negative control group. After the instrumentation process was finished, depending on the group the cat was randomly assigned to, vital perfusion operation was performed 8, 24 and 48 hours later. Then the teeth with its surrounding tissue were resected and sent to lab for decalcification and staining processes and then the samples were examined under a light microscope. Statistical analysis was performed using Kruskal-Wallis test. 48 hours after removing the pulp and linking the periapical tissue to oral cavity via canal system and then instrumentation of the canal using the techniques evaluated in this study, the least inflammation was obtained in 48-hour group after the instrumentation was completed, comparing to 24 and 8-hour groups although this difference was significant only in the edema index (P<0.1). Maximum amount of acute inflammation after pulp expiration is seen 48 hours after it and then, the inflammation decreases in the preapical region in a way that during 48 to 96 hours after expiration, least amount of inflammation is seen in hour 96.

Aspartate aminotransferase is present in gingivial Crevicular fluid, and there is preliminary evidence that its activity may correlate with the extent of gingival inflammation and tissue destruction. Method & Mateial: This work describes a study in which AST was monitored over a one year in 96 Patients with moderate adult periodontitis. Values for plaque index, gingival index and probing attachment level were recorded, and 30- second 3min samples of gingival fluid harvested. As partate aminotransferase activity was determined by a standar method. Our results showed that Aspartate aminotransferase activity in control group was 432.7526.82 and in patient group was 763.4253.27 unit/min/ ml of GCF. Aspartate aminotransferase activities of 500 units in min in ml of GCF or higher appeared to be associate with active disease. Aspartate aminotransferase activity in GCF is strongly related to human periodontal disease. Our results showed that Ast, as a direct measure of tissue damage, will prove to be useful odjunct in the diagnosis of active periodontitis and ultimately aid in the design of more effective therapy.

Some factors can affect T.M.J. In this survey, prevalence of etiologic factors such as trauma, dental premature contacts, parafunctional habits and psychologic factors was studied. Methods & Materials: 100 patients who had T.M.D and referred to Mashhad Dental School was examined. For each patient a questionnaire was provided and etiologic factors evaluated. The most of patients were affected by pscychologic factors (77%). The next lateral eccentric premature contacts were higher than others (71%). Followed by clenching (38%), Bruxism (21%) and Trauma to T.M.J or chin (19%). The most important etiologic factor of TMD was psychologic followed by lateral eccentric premature contacts.

This study was carried out to assess the effect of etching time on the shear bond strength of single bond to primary teeth. Methods & Materials: Two groups, in each group diamond disc to 1.5 mm depth. Group 1 was etched for 7 seconds and group 2 was etched for 15 seconds with 37% phosphoric acid gel. After etching the teeth were rinsed and dried. Single bond was used in two layers and extend along the tooth surface by air and then light cured for 10 seconds. The Z100 (3M) composite was used in same sylanders with 3.2 mm diameter and 5 mm height and cure for 40 seconds. The mean of shear bond strength of groups were: M1: 15.58, M2:13.5 = t test S1:1.12, S2:1.21 T test analysis was shown that the difference between two groups is significant (P<0.0001). Reducing etching time for 15s to 7s leads to increasing shear bond strength of single bond to dentin of primary teeth.

The information about the microbiology of root canal treated teeth with persistent periapical lesion is very important, because the main cause of endodontic failure in such cases is persistent infection. The purpose of this study was to determine the occurrence of Enterococcus faecalis in teeth with failed endodontic treatment in an Iranian population. Methods & Materials: Twenty two asymptomatic root-filled teeth with chronic apical periodontitis were selected for retreatment. After removal of the root – filling material, the canal was sampled with paper points. All samples were grown under aerobic condition at 35 ˚c, then the bacterial growth was accurately analyzed. The finding indicated that bacteria were cultivated in 13 of the 22 (%59) teeth examined in the study. Enterococcus faecalis and staphylococcus aureus were the most commonly recovered bacteria. All cultivable bacteria were isolated in pure culture (monoinfection). It seems that some bacterial species (faculative anaerobes) with a special ecological resistance and high penetration ability have an important role in endodontic failures.

Impression making is one of the most important steps in fixed prosthodontics. Due to contradictory opinions on the issue of the accuracy of silicone impression material as a function of technique, this study was carried out to assess the dimensional accuracy of master casts made by Speedex silicone material as a function of three impression techniques: 2 step with space, 2 steps without space and one step. Method & Materials: This quasi–experimental study, was carried out by using laboratory models. 10 impressions were taken for each technique and stone models were poured. Die’s height, diameter and distance between die’s were measured by profile projector and compared with laboratory model by the use of ANOVA test and LSD analysis. Impression technique has statistical significant effect on dimensional accuracy of master models. 2 step technique with space is the most accurate technique for Speedex impression material. In the presence of undercut under finishing line, one step technique is preferable to two step technique without space.

The majority of carious lesions are not well-defined radiolucencies. Approximately 40% demineralization is required for radiographic detection of a lesion. The actual depth of penetration of carious lesion is deeper than may be detected radiographically. However, digital subtraction images permit to detect 1-5 % decrease of mineral mass per unit volume. The goal of the present study was to evaluate the accuracy of digital subtraction radiography in the detection of dental demineralization in vitro. Methods & Materials: This study was based on observational-diagnostic method which was done on 30 extracted human teeth, categorized in two groups A and B, each having 15 members. In each of teeth, one approximal enamel demineralization lesion was induced using an acidified system (PH=4.8). Direct digital radiography were obtained under standardized condition of teeth before demineralization. After 7 days, the teeth of group B and after 42 days, group A removed from acid and new radiographs were taken. The images of the 7th and 42nd days were subtracted from the baseline radiograph (before creation of the lesion). Then teeth were histologically evaluated. Direct digital and subtraction images were interpreted by three observers to detect presence or absence of the lesion, then the diagnostic accuracy of both methods was determined. After 7 days, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value for incipient lesions in direct digital radiography were 0%, 80%, 40%, 0% and 44% respectively and in digital subtraction radiography were 66.7%, 86.7%, 76.7%, 83.4% and 72.3% respectively. However after 42 days the sensitivity, specificity and accuracy of both methods were 100%. Digital subtraction radiography has a fairly acceptable accuracy in detection of the incipient proximal lesions in comparison with DDR. For moderate proximal lesions DSR has the same accuracy as DDR.

With regard to importance of sealing of gutta percha in the success of endodontic treatment the apical Microleakage of two gutta percha brands (Aria Dent & Dia Dent) was evaluated. Method & Materials: In this experimental study 82 extracted human teeth (single canal, with straight roots, without internal resorption and calcification) were selected. Roots were resected from CEJ and instrumented using the step back technique. The samples were randomly divided in to 4 groups. Group 1: 31 teeth, obturated with Aria Dent gutta- percha. Group 2: 31 teeth, obturated with DiaDent gutta- percha. Group 3: 10 teeth, as a negative control group. Group 4: 10 teeth, as a positive control group. The microleakage was measured using dye penetration and tooth sectioning technique. The deepest linear dye penetration was evaluated by three examiners using stereomicroscope. Then all of the data were analyzed using t-student test. the mean linear dye penetration in the two experimental groups were as follow: Aria Dent 2.67mm. DiaDent 2.63mm.Statistical analysis of results showed no significant difference in apical microleakage between two experimental groups. With regard to the insignificant difference in the sealing ability of the two brands evaluated, AriaDent gutta-percha can be used in laterally condensed obturations instead of Dia Dent gutta percha.

It is important for dentists and specialists to know about impacted wisdom teeth before and after surgery. In this surgery, postoperative complications like infection, bleeding and etc occur by the extraction of this kind of teeth. In this study, the post operative wound infection associated with 100 surgical operations performed during 2000 at OMFS Dept. Shahid Beheshthi Dental School, are reported (4 weeks follow up). Method & Material: This descriptive epidemiological study is performed by completing a data form after observation. This investigation is performed on 100 patients who were physically in a fair status. The patients were accessible easily and they examined at the end of the second and third weeks and the existing signs have been registering. The patients who were suspected of the infection have been following within the next 24 hours. At the end, the last following was performed to evaluating the subperiostal infection after one month. Antibiotics were used in the cases which the surgeon had been used micromotor during the surgery. T-test and one – way and chi – square analysis were used for calculation of the data. The conclusion is announced by p value and if the finding were less than 0.05, they were valuable. The post surgical wound infection rate overall was 6% and the other 94% have passed the usual procedure of recovery. The incidence of infection in the mandible was more than maxilla, and also there was a higher probability of infection in the hard tissue surgery specially in which the surgeon had used micromotor. The triangular flap is caused to infection more than the envelope flap. Most important findings in 100 impacted third molars (100 patients) were:1. In the complicated impacted third molars (like a Cl III or Cl C depth impaction) a new technique with a high concentration are needed. 2. There was relationship between tooth position, flap design, micromotor using and incidence of wound infection that means in all cases with the symptoms of wound infection, impacted wisdom teeth was in the lower jaw, flap design was triangular and practitioner had been used micromotor for removal of third molar. 3. Rate of wound infection not related to the prophylactic use of antibiotic.