مجله دندانپزشکی دانشگاه علوم پزشکی تهران
سال نوزدهم شماره 1 (پیاپی 46، بهار 1385)

Dentistry has always benefited from photography as an adjunct tool in diagnosis treatment planning and presentations. The main reason for taking dental photographs is to provide documents and supplements for treatment. A photograph facilitates communication between dentists and laboratories. Quality control will become more important to dental practice in near future and photographs can be used by dentists as self-checking tools. Nowadays performing lectures or publications without presenting pictures is inconceivable. The camera system must be easy to use and accessories should be always available. Although a good variety of equipments are now available and can be used for close-up photography, the special requirements of dental clinical photography are not always provided by the manufacturers and dealer's recommendations are not always correct. This article tries to help the readers to find and use the most suitable equipments for their routine dental practice.

With recent introduction of packable composites, it is claimed that they apply less stress on tooth structure because of reduced polymerization shrinkage, and similarity of coefficient of thermal expansion to tooth structure. However, the high viscosity may in turn cause less adaptation, so it is not clearly known whether these materials strengthen tooth structure or not. The aim of this study was to evaluate fracture resistance of maxillary premolars, receiving hybrid or packable composite restorations with different methods of application and curing. In this experimental study, seventy five intact premolars were randomly assigned to five groups of 15 teeth each. One group was maintained intact as the control group. Similar MOD cavities were prepared in the other teeth. The teeth in group two were restored with Spectrum in incremental layers and light cured with 500 mw/cm2 intensity. The third group were filled with Surefil and cured with light intensity of 500 mw/cm2. The groups four and five were restored with Surefil in bulk technique with two different modes: 500 mw/cm2 intensity and a ramp mode (100-900 mw/cm2) respectively. After thermocycling, force to fracture was assessed and degree of conversion (DC) at the bottom of cavities was evaluated for different modes and methods. The curing and placement methods in groups tested for DC (A to D) were the same as fracture resistance groups (2 to 5). Data were analyzed using one way ANOVA and Tukey HSD tests with p<0.05 as the limit of significance. All the restored groups showed significantly less fracture resistance than the control group, but had no significant difference among themselves. DC of Spectrum was higher than Surefil. Bulk method with 500 mw/cm2 light intensity, significantly decreased DC. DC in bulk method with high light intensity was not significantly different from incremental method with 500 mw/cm2 light intensity. Placement techniques, light intensity and type of composite had no influence on the fracture resistance. The use of packable composite with bulk technique and 500 mw/cm2 intensity or less is not recommended in 4 mm depth cavities due to insufficient DC.

Increasing patient demands for esthetic, put the root coverage procedures in particular attention. Periodontal regeneration with GTR based root coverage methods is the most common treatment used. The purpose of this study was to compare guided tissue regeneration (GTR) with collagen membrane and a bone graft, with sub-epithelial connective tissue graft (SCTG), in treatment of gingival recession. In this randomized clinical trial study, eleven healthy patients with no systemic diseases who had miller’s class I or II recession defects (gingival recession 2mm) were treated with SCTG or GTR using a collagen membrane and a bone graft. Clinical measurements were obtained at baseline and 6 months after surgery. These clinical measurements included recession depth (RD), recession width (RW), probing depth (PD), and clinical attachment level (CAL). Data were analyzed using independent t test with p<0.05 as the limit of significance. Both treatment methods resulted in a statistically significant reduction of recession depth (SCTG=2.3mm, GTR=2.1mm P<0.0001). CAL gain after 6 months was also improved in both groups (SCG= 2.5mm, GTR=2.1mm), compared to baseline (P<0.0001). No statistical differences were observed in RD, RW, CAL between test and control groups. Root coverage was similar in both methods (SCTG= 74.2%, GTR= 62.6%, P=0.87). Based on the results of this study, the two techniques are clinically comparable. Therefore the use of collagen membrane and a bovine derived xenograft may alleviate the need for connective tissue graft.

Cementation is one of the most critical steps of the porcelain restoration technique. However¡ limited information is available concerning the bond strength of current ceramic bonding systems. The aim of this study was to evaluate the shear bond strength of three dual-cure resin cements to IPS-Empress2 ceramics.
In this experimental study¡ 30 pairs of IPS-Empress 2 ceramic discs were fabricated with 10 and 8 mm diameters and 2.5 mm thickness. After sandblasting and ultrasonic cleaning¡ the surfaces of all specimens were etched with 9% hydrofluoric acid for 60 seconds. Then¡ the three groups of 10 bonded specimens were prepared ceramic bonding resin systems including Panavia F2¡ Variolink II and Rely X ARC. After storage in 37±1c water for 24 hours and thermocycling in 5c and 55c water for 500 cycles with 1-minute dwell time¡ the shear bond strengths were determined using Instron machine at speed of 0.5mm/min. Data were analyzed by One Way ANOVA test. For multiple paired comparisons¡ the Tukey HSD method was used. The mode of failure was evaluated by scanning electro microscope (SEM). P Significant differences were found between different cement types (P Based on the results of this study¡ according to the highest mode of cohesive failure¡ Variolink II seems to have the strongest bond with IPS-Empress2 ceramics.

Although the use of adhesive systems can be effective in decreasing microleakge, it is still a major problem in composite resin restorations. The aim of the present study was to evaluate the marginal sealing ability of resin composite restorations using four dentin bonding systems in both primary and permanent teeth. In this experimental study, one hundred and sixty extracted human teeth (80 primary and 80 permanent) were selected. All of the samples received a class V cavity preparation on the buccal surfaces (The coronal half in enamel and the gingival half in cementum or dentin). Each group was then divided into four subgroups each containing 20 teeth. Four different dentin bonding systems (Scotchbond Multipurpose, Single Bond, Clearfil SE Bond and Prompt L-Pop) were used in each subgroup. Then the cavities were filled with composite resin (Z100 for SBMP and Clearfil AP-X for Clearfil SE Bond). Samples were thermocycled, immersed in 0.5% basic fuschin, cut faciolingually and evaluated for dye penetration using a binocular stereomicroscope. Kruskal-Wallis and Dunn tests were used for comparison of microleakage between groups with p<0.05 as the limit of significance. The results showed that: There was significant difference in microleakage among four adhesive systems in both incisal and gingival margins of permanent teeth and in incisal margin of primary teeth (P=0.000, P=0.002, P=0.000 respectively). There was no significant difference in microleakage of restorations with each of four systems between permanent and primary teeth in both incisal and gingival margins except for PLP, which showed a significant different microleakage in the cervical margins (P=0.009). PLP showed better cervical seal in primary teeth compared to permanent teeth. Clearfil SE Bond showed acceptable results at incisal and cervical margins in primary teeth in comparison to other bonding systems. Based on the results of this study, CSEB, SB and SBMP systems showed acceptable clinical results in primary and permanent teeth. Only PLP showed weak results in reducing microleakage. CSEB can be used successfully in primary teeth because of simplicity and reducing leakage in primary dentin and enamel.

Water sorption and solubility are important properties of acrylic resins. Denture base acrylic resins have low solubility. This solubility results from the leaching out of unreacted monomer and water soluble additives into the oral fluids. The solubility of denture bases can cause oral soft tissue reactions. In addition, water absorbed into this material acts as a plasticizer and decreases the mechanical properties such as hardness, transverse strength, fatigue limit and also can change the color and dimensional stability. The aim of this study was to compare the water sorption and solubility of Acropars and Meliodent heat cure acrylic resins. This experimental study was performed on the basis of ADA specification No.12 and ISO No.1567 and standards NO: 2571 of Institute of Standards & Industrial Research of Iran. Six disc form samples of each acrylic resin were prepared, with the dimension of 50×0.5 mm. After desiccating, the samples were kept in an oven for 24 hours and weighed. Then they were immersed in water, kept in oven for 7 days and weighed again. After this phase, the samples were carried to a dessicator, for 24 hours and kept in an oven for drying and were weighed for the third time. Data were analyzed with Mann Whitney and one sample t-test. P<0.05 was considered as the limit of significance. Water sorption mean values were 30.5±0.1 µg/mm3 or 0.76±0.01 mg/cm2 for Meliodent samples and 30.7±0.87 µg/mm3 or 0.77±0.009 mg/cm2 for Acropars samples. No significant difference was observed in water sorption of these two materials (P=0.9). Meliodent acrylic resin showed lower solubility (1.7±0.097 µg/mm3 or 0.042±0.001 mg/cm2) than Acropars acrylic resin (2.5±0.13 µg/mm3 or 0.062±0.001 mg/cm2) (P=0.002). Acropars heat cure acrylic resin matched well with the requirements of the international standards for water sorption, but its solubility was not favorable. This problem is probably the result of high concentration of residual monomer, the amount and type of cross linking agents and plasticizers as well as the amount of water soluble additives in this material.

The hormone receptor status in breast cancer has been pivotal in determining the likelihood of response to hormonal manipulation. Tumors which are both estrogen and progesterone receptor positive are much more likely to respond to anti-hormone therapy than negative tumors. There is well-established similarity between breast tissue and salivary glands. The aim of this study was to evaluate the progesterone receptor expression in pleomorphic adenoma and adenoid cystic carcinoma of salivary glands. In this descriptive study, immunohistochemical staining with progesterone antibody was performed on 14 pleomorphic adenoma (PA) and 15 adenoid cystic carcinoma (ACC) paraffin blocks. The percentage of positive cells was determined using an eye piece graticule. Immunoreactivity was categorized as either positive (reactivity more than 5%) or negative (reactivity less than 5%). In addition the existence of progesterone receptor in tumor cells, stromal cells (fibroblasts), inflammatory cells and salivary glands around tumors was evaluated. Data were analyzed with T and Mann Whitney U tests with p<0.05 as the limit of significance. Immunohistochemical staining for progesterone receptor was negative in 15 ACC and 13 PA. Only one case of PA showed immunoreactivity for progesterone receptor. Also, 12 normal salivary glands around tumor were positive. Inflammatory cells, endothelial cells and fibroblasts did not show immunoreactivity in most cases. The results indicate the lack of progesterone receptor expression in ACC and PA of salivary glands.

Several factories produce dental cartridge in the world. In Iran, Daroupakhsh company is responsible for this task. The aim of this study was evaluate some properties of daroupakhsh cartridge and compare them with two imported ones: Ecocaine (made in Italy) and Septodont (made in France). In this experimental study, 70 healthy patients from maxillofacial clinic of Shariaty hospital were selected. After obtaining informed consent, 0.1 cc of each carpule was injected to the patient's frontal region and the extent of anesthesia was measured at different time intervals. Also the quality of injections was evaluated by 11 surgeons. The dimensions of the three cartridges were also measured and compared together. Data were analyzed by repeated measure ANOVA and Friedman with p<0.05 as the limit of significance. There was no significant difference in extent and duration of anesthesia among the studied cartridges. Surgeons were equally satisfied of all three kinds of cartridges. All of the cartridges were aspirable. Based on the results of this study, the three studied cartridges had similar properties.

Radiography is the most commonly used technique in root canal length determination, but its application in pedodontics is difficult due to many problems such as radiation hazards, superimposition of permanent teeth buds and uncooperative children. The aim of this study was to investigate the accuracy of an electronic apex locator (Dentaport ZX) in measuring the root canal length of primary teeth in vivo. In this test evaluation study, pulp tissues of 52 primary teeth planned to extraction were removed and the canal length were measured by Dentaport ZX. After extraction, real lengths of canals were measured by using# 15 K-Type file with 0. 1 mm accuracy and both measurements were compared. Data were analyzed by Smirnov Kolmogorov, chi-square, ANOVA and intraclass correlation and p<0.05 was considered as the limit of significance. The difference between the canal lengths measured by eye and Dentaport ZX was–0.17±0.384 mm. Maximum deviation of the real length of canals was between-0.2 to+0.2 mm from apical foramen. Accuracy of Dentaport ZX in the range of-0.2 to+0.2 from apical foramen was 66.96% and in the range of-0.5 to+0.5 from apical foramen was 92.17%. Based on the results of this study, the use of Dentaport ZX in endodontic treatment for primary teeth could be advisable.

Infection control is an important issue in dentistry. Without an efficient infection control, pathogens left on instruments and working surfaces will have potential danger to patients’ health. In this research, antiviral effect of three disinfectants: 0.5% sodium hypochlorite 0.05% sodium hypochlorite and Deconex 50 AF, on HBV was investigated. In this interventional (before-after) study serums of 26 HBV positive patients were analyzed by PCR HBV analysis and 9 contaminated species were obtained to test three disinfectants. 36 agar plates were prepared with the contaminated serums. 27 of the plates were disinfected in 3 separate groups with the above mentioned solutions. Nine remaining plates were not disinfected (control). Swabs wetted by BSAS (Bovine Serum Albumin Sodium Chloride) medium were applied on the surface of the plates and the were kept in the transferred medium and sent to virology-lab of Pasteur Institute. HBV DNA were detected by commercial kit of HBV PCR (polymerase chain reaction) method. Data were analyzed by Cochrane test with p<0.05 as the limit of significance. None of samples disinfected with 0.5% sodium hypochlorite showed contamination. 11/1% of samples disinfected with 0.05% sodium hypochlorite and 44/4% of samples disinfected with Deconex 50 AF remained contaminated. Statistical analysis showed a significant difference between 0.5% sodium hypochlorite and the other groups. Our findings revealed that 0.5% sodium hypochlorite solution is a strong and efficient disinfectant against HBV. Key Words: HBV Sodium hypochlorite.

Lead is one of the most dangerous metallic poisons which can lead to acute and chronic poisoning with a broad range of systemic and oral signs. The aim of this study was to evaluate the relationship between the prevalence of oral complications and blood lead level in workers employed in Koushk lead mines, Yazd province. This analytical study was conducted on 70 subjects employed in Koushk lead mines and 70 workers in Yazdbaf textile factory as control group. A questionnaire including demographic information and medical questions was completed for each case and oral manifestations were recorded, as well. Blood samples were taken from subjects and blood lead level was measured by atomic absorption spectrophotometer. Data were analyzed using t, Chi-Square and Mann Whitney tests with p<0.05 as the limit of significance. The mean lead level was 7.06 µg/dl in case group and 4.97µg/dl in control group (P= 0.039). In case group, 3 subjects had blood lead level more than 20µg/dl. Statistical analysis showed significant differences regarding neurologic disorder, chronic fatigue, existence of lead line, mucous pigmentation, gingivitis, tongue burning, taste sense reduction and DMF between case and control groups (P<0.05). Based on the results of this study, since the mean blood lead level in mine workers was in normal limits, the observed symptoms were not related to systemic poisoning. Direct contact of the oral mucosa with the lead in breathing air or other factors related to overall health problems in mine workers may be responsible for the present findings. Further studies are recommended on similar subjects working in different conditions.

Langerhans cell histiocytosis (LCH) is a rare disease with formation of granulomatous infiltrations consisting of Langerhans cells, histiocytes, lymphocytes and eosinophilic granulocytes. The ethiopathogenesis of the disease has not been fully clarified yet. It can occur as focal or disseminated form - acute or chronic. Oral manifestations may be the first signs. This article reports a case of a 3 year old boy with LCH suffering from severe dental mobility and foul breathe. Radiographically, the lesions appeared as well-defined radiolucent defects in maxilla and mandible. The microscopic findings consisted of sheet like arrangements of histiocytes with a mixture of eosinophils and other inflammatory cells. Biochemical tests were within normal limits.