مجله دانشکده دندان پزشکی اصفهان
سال دوم شماره 1 (پیاپی 5، بهار 1385)

Full coverage of teeth chosen correctly, could be the best treatment, but because of different steps involved in crown fabrication, dentists must try to make crowns with noticeable duration. The purpose of this study was to evaluate the effect of auxillary preparation elements and occlusal surface modifications on the resistance form of a complete lower molar crown.Methods and materials: This study was of experimental-laboratory type. Ivorine tooth was prepared with 20 degree TOC (Total Occlusal Convergence), 3 mm occlusocervical dimension and shoulder finishing line (First group=control group). Ten standard metal dies were replicated from this model. Standard metal crowns were made for all samples. After the cementation of metal crowns to metal dies with resin cement, the resistance of each samples against lateral forces were determined by instron machine. Next groups consisted of interproximal boxes+ buccolingual grooves (2nd group), occlusal isthmus (3rd group) and reduced TOC at cervical area (4th group) prepared on control group. The other procedures were done the same as for the control group. Data from 4 groups were evaluated by ANOVA and Post Hoc tests. Statistical analysis of the results showed the most significant differences were in the 4th group and then the second group (239.1 and 178.5 kgf respectively). While no statistical differences were found between groups "1&3" (93.8 and 94.7 kgf respectively). The best axial preparation to increase the resistance form was reduced TOC. Preparing boxes+grooves were of second impatance. However lack of axial preparation (group "A") or auxiliary features without favorable effects such as occlusal isthmus (group "C") on teeth with insufficient resistance form does not have any positive effect.

Scaling and root planing is one of the most commonly used procedures during periodontal treatments. Removal of calculus using conventional hand instruments is incomplete and rather time consuming. To find more efficient and less difficult instrumentation method, investigators have proposed lasers as an alternative or adjunct to hand instruments for scaling and root planing. The aim of the present study was to compare the effectiveness of three methods of hand instruments, ultrasonic and Er:YAG laser for scaling & root planing of root surfaces with SEM method.Methods and materials: This was an experimental study and samples included 15 extracted premolars collected from patients with periodontal problem. The teeth were sectioned in two parts vertically. Therefore 30 samples were randomly divided in two groups. In the first group each surface of root from CEJ was divided in two parts. One part was scaled with manual curret and another by Er:YAG laser and third group was cleaned by ultrasonic methods. Another surface was considered as control group. The surface changes were evaluated by SEM in magnification of 50, 400 and 750 by 5 Examiners. Data was analyzed by SPSS program. The findings show that surface roughness is more in control group comparing with three other groups. Besides roughness from the most to the least belong to: ultrasonic group, laser group & manual scaling group. Kruscal-wallis test & Mann-Whitney test showed that there was a significant difference in the amount of surface roughness between manual group & laser group and also between control group & other groups and between manual and ultrasonic group. But there was no significant difference between rate of surface roughness in laser and ultrasounic group. The efficacy of Er:YAG laser for scaling & root planing is not more than manual and ultrasonic instruments the amount of surface roughness created by Er:YAG is more than manual scaling but the difference is not significant comparing to ultrasonic scaling.

Oral Lichen Planus (OLP) is a common mucocutanous disorder with unknown etiology. While current data suggest that oral lichen planus is a cell-mediated autoimmune disease, it might be associated to S+100, CD+4 and CD+8 cells. Because of differential diagnosis of OLP and Oral Lichenoid Lesion (OLL) is usually difficult this study was designed to compare any probable immunohistochemical differences between these lesions.Methods and materials: Formalin-fixed, paraffin- embedded tissue sections of 30 oral lichen planus and 60 oral lichenoid lesions were Immunohistochemically analyzed for number and distribution of S+100, CD+4 and CD+8 cells. A standard Biotin-strerptavidin procedure after Antigen retrieval was used. SPSS-13 software and Mann-whitney test were applied in data analysis. We could not find any significant differences in number and distribution of CD+4, CD+8 cells and distribution of S+100 cells between two groups but Numbers of S100+ cells were higher in epithelium of OLP. The number of S+100 cells in oral lichen planus was different from lichenoid lesions. In spite of similarities betweem these two groups, it seems they may have different pathogenesis. Further studies about mentioned cells with follow up of patients are recommended.

Recent anti-inflammatory group of medications include the introduction of cyclooxygenase-II inhibitors such as coxibs. These agents offer potentially significant advantages because of their realive lack of gastrointestinal irritation. The aim of this study was to evaluate the effect third molar surgery.Methods and materials: This study was a double, randomized, cross over, clinical trial. Fourteen patients in age range of 17-30 years that acted as their own controls underwent bilateral third molar surgery with an interval of 2 weeks between each operation, when the tooth was removed in attention to right or left side of surgery, patients were randomly entered in study every twelve houres, ibuprofen 400mg was taken if pain persisted. Patients in control group took ibuprofen 400mg upon pain. The number of additional analgesic and the time of intake were recorded by patients. There was no significant difference between mean pain intensity in study and control group. The number of ibuprofen used in the study group was less significant. But the number of total analgesic in this group was more than control group. Incidence of first group adverse events was less in study group but there was no significant difference between first group adcerse events in two groups. Use of celecoxib clinically had valuable efficacy in control of postoperative pain after third molar surgery and reduced intake of ibuprofen in patients. Although there was no significant difference between pain intensity in two groups. It appears that because of reducing intake of ibuprofen and fewer first group advers events use of celecoxibe 200mg per 12 hours and ibuprofen PRN is suggested in the patients with first group problems. However in individuals without first group problems, intake of ibuprofen alone is suggested.

Radiographs are of limited value in diagnosis of osseous defects. Anatomic and technical factors affect the radiographic appearance of bone lesions. In this research radiographic appearance of alveolar osseous defects in relation to their anatomic location is evaluated by periapical radiography.Methods and materials: Experimental bone lesions were created in the eight location of alveolar process of a skull. Standardized periapical radiographs were obtained before and after the defects were made. After processing, pairs of radiographs were randomly mounted. Four dentists acted as observers in order to determine whether or not a change in alveolar bone was detectable at each of the eight possible locations. Finally, the twenty Radiographic images taken from each location were randomly arranged and mounted in ten pairs and four dentists were asked to determine whether or not a change in alveolar bone was detectable at each of eight possible locations. After evaluation of the data and statistical analysis, it was concluded that the prevalence of the correct diagnosis in mandibular lesions in contrast with maxilla, and in lingual aspect in contrast with the buccal aspect of the alveolar bone, and in marginal bone in contrast with interproximal region is definitely more. The results showed that the anatomic location of a lesion in the alveolar bone did affect its radiographic appearance. Furthurmore, experimental defects were detected more often in the mandible and on the lingual surface of the alveolar crest and on the marginal bone.

For a successful root canal treatment, canal must be obturated apically, coronally and laterally to prevent microleakage and canal reinfection. Cold lateral condensation is the most popular method of canal obturation; an easy method with a controlled filling. Cold lateral technique disadvantages are presence of void, possible vertical root fracture, and absence of a homogenous and condensed filling. In some techniques like One-step, heat is used to soften gutta-percha for better adaptation to canal walls. The purpose of this study was to compare of the apical microleakage in roots obturated with One-step and lateral condensation techniques.Methods and materials: In this in invitro study ninety extracted human maxillary central incisors, canines, and mandibular premolar (single rooted teeth) were instrumented to a size 40 file and step back flaring was performed to a size 80 file. Apical patency was ensured in all teeth. The teeth were divided into two experimental groups of 40 each and two positive and negative control groups. In the first experimental group, the roots were obturated with lateral condensation gutta-percha technique and AH26 as a sealer. In the second experimental group, the roots were obturated with One-step technique and AH26 according to the instruction of manufacturer. All roots were placed in humidor with 100% humidity and incubated at 37ºc for 3 days to allow the sealer to set. After achieving coronal seal, the roots were coated with two layers of fingernail polish and one layer of stickywax except for the apical 2-3mm and then placed into India ink and incubated at 37ºc for 72h. The roots were removed from the dye, fractured longitudinally and liner dye penetration was measured. The mean apical dye penetration in laterally condensed technique and One –step technique were 3.60±2.03 mm and 4.00±2.23 mm respectively. Dye penetration in negative control group was zero, and in the positive control group dye pentrated through all the canal system. Statistical analysis of the results did not show significant difference between two groups. Although there was no statistical difference in the sealing ability of laterally condensed and One-step techniques, further in vivo and in vitro studies are needed to prove the clinical abilities of One-step technique.

Evaluation of bonding in atomic level, by SEM/EDS analysis of Si atoms, is an exact method for determination of bond strength of metal and porcelain. The purpose of this study was to evaluate the bond strength of one noble alloy and two base metal alloys with and without beryllium.Methods and materials: Six specimens of each alloy Begostar, Rexillium III, Wiron 99 (10×10×1mm dimensions) were prepared. All specimens were airabraded with 50 μm aluminium oxide particles. Vita VMK 95 porcelain was fused on the central 6 mm diameter circular area of each specimen with 1 mm thickness. Porcelain was debonded by planar-shear test at a cross- head speed of 0/5 mm/min. Specimens were analyzed by SEM/EDS (Scanning Electron Microscope/Energy Dispresssive Spectroscopy) analysis 3 times throughout the study to determine the Si atomic percentage. Bond strength of porcelain to alloys was characterized by determining the Area Fraction of Adherent Porcelain (AFAP). Results were analyzed by one-way analysis of variance and LSD test. Statistical analysis showed a significant difference in the AFAP values among groups. AFAP value of noble alloy group (0.97±0.07) was significantly higher than other groups. For base metal groups, AFAP value of beryllium group (0.45±0.13) was significantly higher than non-beryllium group (0.17±0.04). Superior AFAP values of noble alloys, confirm better bond strength between noble alloys and porcelain as compared with base metal alloys. Also, in base metal alloys, specimens with beryllium, have a higher AFAP values and higher bond strengths.

The antibacterial agents are generally safe, but the list of possible adverse reactions is very long. Adverse antibiotic reactions can involve every organ and system of the body and are frequently mistaken for signs of underlying disease. Similarly, the mouth and associated structures can be affected by many antibiotic or chemicals. Regarding different parts of the oral system, these reactions can be categorized to oral mucosa and tongue, dental structures, salivary glands, periodontal tissues, cleft lip and palate, taste disturbances, muscular and neurological disorders.The knowledge about antibiotic- induced oral adverse effects helps dentists and physicians to better diag-nose oral disease, administer antibacterial agents, improve patient compliance during antibiotic therapy, and may influence a more rational use of drugs.