JOURNAL OF DENTISTRY (SHIRAZ UNIVERSITY OF MEDICAL SCIENCES)
Year:2012 | Volume:13 | Issue:3 (36)|Papers Count:8

Statement of Problem: Several dilemmas have been reported with regard to the retention and longevity of implant-retained over dentures. A few studies have investigated the influence of implant and attachment inclination on the path of insertion and withdrawal of the prosthesis and on the retention and longevity of the over denture. However, no study has been reported with regard to the influence of labio-lingual inclination on the aforementioned indices.Purpose: The purpose of this study was to investigate the influence of implants and attachments with 5 and 10 degrees of inclination on the retention and longevity of implant-retained over dentures.Materials and Method: In this experimental study, 10 implants and 50 attachments were selected and divided into five groups: Group I: two implants and attachments parallel to each other, Group II: implants inclined at an angle of 5 degrees and attachments without any inclination, Group III: implants and attachments inclined at an angle of 5 degrees, Group IV: implants inclined at an angle of 10 degrees and attachments without any inclination, Group V: implants and attachments inclined at an angle of 10 degrees. All the attachments and implants were lubricated by artificial saliva. Initial retention (N) of blocks was measured through the Universal Testing Machine (SANTAM, STM-20). The blocks were removed and replaced for 3000 cycles and retention was measured after each 500 cycles. The retention was measured five times for each group and the registered data were analyzed by One-way ANOVA and T-test.Results: The maximum and minimum amounts of initial retention were 5.54±0.3 and 3.88±0.19 and were related to groups III and I, respectively. There was no significant difference among groups II, III, IV, and V with regard to the amount of retention of implants and attachments (p<0.3). However, there was a significant difference between the control group, group I, and the other groups (p<0.01).Conclusion: Although the placement of labially inclined implants results in an increase in the initial retention, it will lead to a large decrease in the amount of retention after the last cycle. However, this amount of inclination (5 or 10 degrees) does not have any negative effect on the prosthesis longevity.

Statement of Problem: Dentists and dental laboratory technicians' awareness of the dangers of cross-contaminations has made them seek the best ways to control and eradicate the main sources of infections.Purpose: The aim of this study was to evaluate the effects of spraying Deconex on three different impression materials.Materials and Method: In this in vitro experimental study, 30 circular samples of different impression materials, such as alginate, silicone and polyether impression materials were separately contaminated with Staphylococcus aureus (ATCC29213), Pseudomonas aeruginosa (ATCC27853), and Candida albicans fungus (PTCC5027).Except for the control samples, all the other samples were disinfected with Deconex through spraying. Then, they were kept in plastic bags which were stuffed with humid rolled cotton for 5 and 10 minutes. In order to isolate bacteria, the samples were immersed in 2% trypsin for one hour and then the solution was diluted with normal saline in proportion of 1, 1/2 and 1.4. The trypsin suspensions were transferred to culture plates and the number of colonies was counted after 24 and 48 hours for bacteria and after 72 hours for fungus. Data analysis was done through running Mann-Whitney Test (a=0.05).Results: There was a significant difference between the effect of Deconex on silicone and its effect on polyether for all the mentioned microorganisms after 5 minutes (p<0.05). The highest percentage of bacterial growth prevention was recorded for silicone impression material. Deconex completely eradicated the three kinds of microorganisms after 5 and 10 minutes in the silicon group. Deconex was not capable to eliminate all three microorganisms in the polyether and the alginate groups, with the exception of Pseudomonas aeruginosa after 10 minutes.Conclusion: The results of the present study indicated that Deconex has the highest capacity when it is used with silicone, it eradicates all microorganisms in both 5 and 10 minutes.

Statement of Problem: Oral biopsy is important in the definite diagnosis of oral and maxillofacial lesions. This procedure as well as other laboratory services is prone to errors affecting the patients' safety.Purpose: The purpose of this study was to evaluate pre-analytical biopsy specimen errors in the Oral Pathology Laboratory of Hamedan School of Dentistry, west of Iran.Materials and Method: Ninety-one oral biopsy samples, obtained from departments of oral and maxillofacial surgery (34 samples, 37.3%), oral medicine (22 samples, 24.3%) and periodontics (10 samples, 10.9%), as well as private offices (16 samples, 17.6%) and hospitals (9 samples, 9.9%) were received and evaluated in the Oral Pathology Laboratory of Hamedan School of Dentistry considering pre-analytical errors.Results: The errors in the request forms included unmentioned names of patients (7.7%), age (3.3%), clinical history (4.4%), site of biopsy (10.9%), differential diagnosis (18.7%) and the name of the requesting clinician (8.8%), as well as lack of radiographs (4.4%) and previous biopsy results (2.2%). Use of inappropriate fixative (5%), and specimen-containers with non-proportional volume (3%), and their small size inlets (3%) was also reported. Non-standard containers were seen in 19% of the cases, and mislabeling errors (31 missed, 2incomplete defects, and 1 incorrect) in 34% of the cases. Of 105 specimens, 6.67% were small in size, 1.90% superficially removed, and 0.95% had been traumatized. Out of the 5 containers with more than one specimen, 4 containers did not have any markers.Conclusion: Considering the biopsy errors in the study specimens, training and surveillance to reduce the frequency of such errors seems necessary.

Statement of Problem: One fourth of orthodontic patients can benefit from maxillary expansion but traditional expansion screws produce unfavorable heavy interrupted forces. A new spring- loaded expansion screw was designed which created light and continuous forces.Purpose: The purpose of this study was to compare the treatment effects and patients, discomfort with removable slow maxillary expansion and newly designed spring loaded expansion screw.Materials and Method: 35 healthy Iranian children were divided randomly to two groups: group I (25 patients) treated by removable expansion appliance and group II (10 patients) treated by spring- loaded expansion appliance. The active phase of expansion was monitored and arch sizes of the upper dental arches (inter- canine, inter- premolar, inter- molar and arch perimeter) were measured with a caliper on casts monthly. The patients requested to mark the intensity estimation of their discomforts during wearing of appliance on questionnaires which comprised 12 statements. The scores of individual question were added up to obtain a total score. The independent t test and Mann- Whitney U-test were applied to analyze the data.Results: There were no significant differences in both groups in the mean of arch size changes in each appointment (p>0.05). There was no significant difference in both groups in terms of the mean of scores of questionnaires (p=0.352).Conclusion: There was no significant difference in terms of patients, discomfort and arch size changes in spring-loaded and removable expansion appliances. Since the newly designed expansion appliance does not need to be activated by patients, it might be assumed a proper substitute for traditional expansion appliances.

Statement of Problem: Although the basic use of tissue conditioners is to treat inflamed mucosa, they are also employed as functional impression materials. No information was obtained on the reproduction of surface detail of these materials over time.Purpose: The purpose of this study was to evaluate changes in the surface quality of three tissue conditioners after being immersed in water for a period of time.Materials and Method: Detail reproduction was determined by using from a ruled test block the same it was specified in ISO Specification 4823. Three tissue conditioners (GC, Acrosoft, and Visco-gel) were evaluated. Samples were made by pouring freshly mixed materials into a ruled test block. The samples were then stored in distilled water for either of the followings periods of time: 0 hour, 24 hours, 3 days, 7 days, 14 days. Subsequently, the dental stone was mixed with distilled water and poured on each sample and allowed to remain for 60 minutes. Then, 25 specimens were prepared. The detail reproduction was determined based on what is specified in ISO Specification 4823. The samples were examined under a stereo-microscope with low-angle illumination. The data was analyzed through running Kruskal-Wallis Test and Mann-Whitney Test.Results: The three materials had minimum standard of detail reproduction. The detail reproduction were more significantly influenced by the time period of immersion in water (p<0.0005) than the type of the material. The best detail reproduction was pertained to Visco-gel not immersed in water. Acrosoft was less influenced by the time period of immersion in water than the two other types.Conclusion: The detail reproduction may be attributed to chemical composition. The type of material and immersion time had a significant effect, while the effect of the type was less significant. The best time for making functional impressions was ranges from 0 to 24 hours.

Statement of Problem: After 30 years of intermittent reports in the literature, the use of fiber-reinforcement is just now experiencing rapid expansion in dentistry.However, there are some controversy reports in the amounts of flexural strength of fiber reinforced composites to use them as bridges.Purpose: The purpose of this study was to evaluate the flexural strength of three commercially available fiber-reinforced composites including Belle Glass, GC Gradia, and Signum.Materials and Method: Thirty uniform bars of 25×2×2 mm (10 for each group) were fabricated as their manufacturers recommended. Then all specimens were loaded to failure using a three-point bending test and flexural strength was determined.Results: The mean flexural strength of Belle Glass (386.65 MPa) was significantly (p<0.0001) higher than that of GC Gradia (219.25 MPa) and Signum (172.89 MPa). There was no significant difference between GC Gradia and Signum in flexural strength.Conclusion: On the basis of these findings, Belle Glass can be used in clinical practice with greater confidence compared to GC Gradia and Signum.

Primary leiomyosarcoma is a rare tumor in the head and neck. This report is to describe a case of maxillary leiomyosarcoma in a 36-year-old man, who was referred to Chamran Hospital (Shiraz, Iran) in September 2009. The patient was diagnosed with leiomyosarcoma, originated in the left premaxilla. Histogenetically, maxillary leiomyosarcoma arise from the medial muscle of blood vessels or from primitive mesenchyme in the maxilla (1). The lesion was treated with surgical resection; Midface Degloving procedure. The primary site received postoperative radiotherapy with external irradiation of 45 GY (25 treatments, 1.8 GY). The patient was monitored at follow-up visits in the next one year.

Cementoblastoma is a rare benign neoplasm of cementoblastic origin which is usually represented with marked swelling and severe pain. In this article, the mechanism of pain generation and definite diagnosis of a cementoblastoma related to the first mandibular molar with a long-lasting dull pain have been discussed.