مجله دانشکده دندان پزشکی اصفهان
سال پنجم شماره 4 (پیاپی 20، زمستان 1388)

Disinfection of dental impressions is mandatory for decreasing the risk of infection transmission to dental laboratory. Polyethers are one of the most popular and precise impression materials. The aim of this study was to evaluate the disinfecting potential of 2% Sanosil on polyether impression materials via immersion and spray methods. Sixty three circle specimens (1 cm diameter and 2 mm thickness) of polyether impression materials (Impregum F) were contaminated with Staphylococcus Areus (ATCC 29213), Enterococcus Feacalis (ATCC 51299), and Candida Albicans (PTCC 5027). Except for control samples, all specimens were immersed in or sprayed with 2% Sanosil for 5 and 10 minutes (5 samples for each disinfection methods and 1 control). Tripsin was used for separating of microorganisms. 1, 1/2 and 1/4 concentrations of the tripsination solution were analyzed microbiologically for Colony–Forming Units (CFU). The number of CFUs per milliliter was counted at 24 and 48 hours for the bacteria and 72 hours for Candidia Albicans. Mann-Whitney and Wilcoxon tests were used for data analysis (α = 0.05). With both spray and immersion methods, the number of CFUs decreased with increasing the disinfecting time and increased with longer incubation time. The CFU counting of Staphylococcus Areus in 5 and 10 minutes immersion in 2% Sanosil were significantly less than spraying method (p value < 0.05). The difference between the two methods in 5 minute disinfection was not significant for Enterococcus Feacalis, however in 10 minute disinfection the immersion proved significantly more effective. The number of CFUs for Candidia Albicans after an incubation of 72 hours was less with 5 minute immersion compared to 5 minute spray. The two methods did not show significant differences in 10 minute disinfection. Spraying with and immersion in 2% Sanosil have high level bacteriocidal effect on Staphylococcus Areus (99.99% and 100%, respectively) and less effect on Enterococcus Feacalis (88% with spraying and 96% with immersion). 2% Sanosil has high effectiveness in disinfection of Candida Albicans (99% with spraying and 99.99% with immersion).

One of the most important factors in long-term success of implant supported restorations is an accurate transfer of implant position by means of impression techniques. This study was designed to evaluate the effect of Implant Abutment Connection (IAC) on the accuracy of impression with different implant angulations and two different impression materials. A stainless steel model containing 10 implants (5 with external and 5 with internal connection) was fabricated with 0, 15, 30 and 40 degrees angulations. An open-tray impression technique was performed, using a custom tray and polyether (n = 30)/monophase polyvinyl siloxane (n = 30). The impressions were poured by stone type IV. The orientation of implants on the master models and the samples was evaluated by coordinating measuring machine (CMM) with 1 µm precision. Two-way analysis of variance and t-student test were used for statistical analysis via SPSS software. (α = 0.05) No statistical differences were found between the two impression materials. There was also no significant difference between connection types in implants with 15˚and 30˚ angulations. However, 40˚ angulations showed higher degrees of error, using internal IAC. Types of connection along with implant angulations seem to have great impacts on impression precision. As observed, 40˚ implants with internal connection reduced impression precision.

Recurrent Aphthous Stomatitis (RAS) is one of the most common oral mucosal disorders. RAS patients show a decline in oral tolerance which leads to epithelial damage. Cortisol secretion in such patients may not be enough to suppress cytotoxic reactions against oral epithelium. The aim of this study was to measure salivary cortisol level during both ulceration and ulcer free phases of the disease. In this analytic-descriptive study, a total of 20 patients having minor oral aphthi with a history of at least three times oral ulceration in one year were included.Saliva samples were collected through spitting. The salivary concentration level of cortisol was measured on the first and 7th days from the appearance of aphthous ulcers, every patient was considered as both case and control. Sampling was repeated when ulcers were completely healed. The saliva samples were collected between 9 and 10 am and were analyzed via Enzyme-Linked Immunosorbent Assay (ELISA). The collected data were statistically analyzed on a computer through repeated measurement ANOVA and paired t-tests using SPSS software.(α = 0.05) The mean concentration of salivary cortisol on the first day of aphthous appearance was 2.72. However after complete healing of the ulcers, it rose to 3.37. The difference these values were shown to be statistically significant (p value=0.002). The mean concentration level of salivary cortisol on the 7th day from aphthous appearance (2.6) was also significantly different from the aphthous Free State. (p value = 0.001). Mean cortisol concentration level on the first and 7th days from the appearance of aphthous ulcer did not show a significant difference (p value = 0.304). The results showed that the mean salivary cortisol level at the beginning of the disease as well as during its active ulcerative period (acute phase) were significantly lower than in aphthous free periods. It seems that cortisol plays a key role in reducing aphthous ulcer inflammation. Impaired cortisol secretion in RAS patients may cause an increased rate of incidence and severity of aphthous ulcers.

Though sliding techniques are quite common in orthodontics, the produced friction however hampers ideal movement of teeth. Increased friction not only necessitates a greater orthodontic force but also results in anchorage loss. The aim of this study was to evaluate frictional changes of steel brackets on stainless steel wires while sliding. In this experimental study a total of 69 stainless steel brackets (Dentaurum) with 0.018 inch slots were randomly divided into three groups of 23 brackets. With each group either 0.016 or 0.016 × 0.016 or 0.016 × 0.022 inch steel wires of the same company (Dentaurum) were used in combination with brackets. There were 5 slots on each piece and every slot was 1mm apart from the next. Therefore each piece of wire was pulled via Dartec machine in every bracket slot with an average speed of 0.5mm/min in five sections. The amounts of friction were recorded. The collected data were then compared with repeated measurement ANOVA and paired sample T-test.(α = 0.05) Three brackets were randomly examined under scanning electron microscope (SEM) at the beginning and after the first, the third and the fifth tractions. Repeated measurement ANOVA showed statistical significant differences in static and kinetic frictions between first to fifth tractions in three sizes of wires. Based on paired sample t-test, significant differences were seen between first traction and the others. However, differences between the third and the forth, the third and the fifth and the forth and the fifth tractions were not significant between the three sizes of wires and the two kinds of frictions. It seems that friction would decrease during sliding of steel brackets on steel wires. Diameter and cross section of wires would have little effect on friction.

In addition to its role in preventing dental caries via remineralization, it has been shown that CPP-ACP can also protect teeth against erosion. The aim of this study was to determine whether CPP-ACP could reduce enamel wear rates under erosive conditions simulating attrition and low PH diet. In this experimental in vitro study, enamel specimens were subjected to 5000 wear cycles at a load of 3Kg and PH = 3(citric acid as media) in a tooth wear machine. Enamel specimens were divided into 2 groups (n = 9). CPP-ACP in the form of a paste was applied on the samples in the test group for 15 minutes. No treatment was given to the control group. The machine was stopped every 1000 cycles and the same protocol was repeated in the test group for 5 times (totally 5000 cycles). The amount of wear was examined with stereomicroscope. The collected data were then analyzed on a computer via T-test and repeated measurement ANOVA using SPSS. (α = 0.05) T-test indicated that the mean wear rate in the test group (39.09 ± 9.84 micron/1000 cycles) was significantly lower than that in the control group (53.24 ± 4.54 micron/1000 cycles)(p value = 0.004). CPP-ACP as a bioactive substance can reduce enamel attrition in acidic condition. Further studies on how such bioactive substances can clinically control wear seem to be of great advantage.

Temporomandibular Joint (TMJ) is an important and complicated joint in the body with a critical role in chewing and speech. Some 50% to 60% of people are said to have a kind of disorder in their TMJs. Among those, 5%-10% suffer from acute or chronic dislocation of TMJ.The definitive treatment for this problem is surgery which of course has probable side effects such as ankylosis and facial nerve injury. Also, Routine conservative treatment just subside symptoms for a period of time. In this study, we evaluated if autologous blood injection in TMJ can be an acceptable conservative treatment for TMJ dislocation. This was a case-control experimental study including 10 rats. The right side TMJs formed the case and the left ones were considered as the control group samples. They were divided into 5 groups so that each group consisted of 2 rats. The groups were sacrificed on days 1, 3, 7,14 and 28. Both of TMJs on every individual were prepared for histological study. Fibrosis was assessed via digital imaging. The collected data were then statistically analyzed by SPSS statistical software using Wilcoxon test.(α = 0.05) The amount of fibrosis in the case group was statistically higher than in the control group (45.95% versus 34.44%) Blood injection into TMJ seems to be a simple and cost-effective therapeutic choice for patients with recurrent TMJ dislocation.

them to patients is substitution of debonded teeth in their places. Several studies have already been planned to study the factors affecting the bonding strength of artificial teeth to their denture acrylic base resin. The aim of this study was to make a review on the factors which affect bonding strength of artificial teeth to the acrylic denture base resin.Methods and Materials: A thorough literature review was made on the web using Pubmed and Science Direct services. The key words applied for the search were acrylic, dentures, tooth, artificial, denture bases, bonding strength. Since 1952, a total of 54 relevant papers were selected. There is a wide variety in methodology of testing the samples for bond strength. Contamination with wax appears to be the major cause of bond failure between teeth and denture base resins. Also contamination with tin foil substitute seems to reduce bond strength. Application of monomer or adhesive bonding agents and chemicals to acrylic teeth can enhance bond strength values. Heat activated resins produced a higher bond strength than other types of acrylic resins.

Schwannoma or Neurilemoma is a benign neoplasm of the nervous system originating from Schwann cells. It develops from the neural sheath of peripheral motor, sensory, sympathetic, and cranial nerves except for the optic and the olfactory nerves which basically lack Shwann cell sheaths. Approximately 25% to 45% of the schwannomas occur in the head and neck region. Usually, the mass is asymptomatic, though tenderness or pain is reported in some instances. Tongue is the most common site for oral neurilemomas. Occasionally, the tumor arises centrally within the mandibular bone and thus makes jaw expansion.Case Report: A 22-year-old man presented with a mass in the right side of his mouth floor allegedly existing from six months earlier. The mass was surgically removed. Sample sections of the mass were prepared. In microscopic examination with H&E, there were two areas of wavy and spindle cells within a loose and myxomatous stroma compatible with the known Antoni A and B patterns of Schwannoma. The tumor cells showed a diffuse positive immunohistochemical reaction to S-100 which supported the diagnosis. Schwannoma is a benign soft tissue tumor which mostly involves tongue within oral cavity. This tumor rarely occurs in other regions such as mouth floor.