Journal of Dental Medicine

Giant cell granuloma: a cross- sectional study in oral and maxillofacial pathology department of dental faculty of Tehran University of Medical Sciences (1986-2000)

Statement of Problem: Giant cell granuloma (G.C.G) is a reactive lesion which affects the jaws and oral mucosa of gingiva.This lesion is classified to central and peripheral ones. The histopathologic aspects of central and peripheral G.C.G is the same. The central lesions are aggressive and cause osseous destruction. The peripheral G.C.G produces ulcerative swellings similar to pyogenic granuloma or peripheral ossifying fibroma. Since the peripheral and central G.C.G are common lesions, the awareness of dentists of different aspect of G.C.G is very important.

Purpose: The aim of this study was a statistical evaluation of variables such as age, gender and location of peripheral and central G.C.G in oral and maxillofacial pathology department of Dental Faculty of Tehran University of Medical Sciences.

Materials and Methods: This study was a cross-sectional, case series one. The medical records of oral and maxillofacial pathology department of Dental Faculty of Tehran University of Medical Sciences was assessed in two steps: In the first stage, the medical records of patients with pathologic report of peripheral and central G.C.G were selected and reviewed. In the next step, the informations such as age, gender and location of peripheral and central G.C.G were registered in data forms. The obtained data were analyzed by SPSS statistical software.

Results: The results showed that the age range in peripheral and central G.C.G were 2- 90 and 4-70 years, respectively. The peak incidence of peripheral and central G.C.G was in the third and second decades, respectively. The peripheral G.C.G was more common in men (52.70%) than women (47.30%). This finding in central G.C.G was 37.19% for men and 62.88% for women. 57.06% of peripheral G.C.G cases were in mandible and 42.94% in maxilla. The occurrence of central G.C.G was 67.07% in mandible and 32.93 % in maxilla.

Conclusion: Based on this study, the peripheral lesions were more frequent in men, third decade and mandible and the central lesions in women, second decade and mandible.

Effect of three porcelain etchants type (HF-APF-PHA) on porcelain- composite shear bond strength

H. Kermanshah

Statement of Problem: Porcelain restorations are susceptible to fracture and a common method for repairing is the use of silane and composite on etched porcelain. Although HF is very effective in porcelain etching but has detrimental effects on tissues.

Purpose: In this study, the effect of APF and PHA was compared with HF in porcelain etching. Also the role of silane, unfilled resin and dentin bonding in bond strength of composite- porcelain was evaluated.

Methods and Materials: In this experimental in-vitro study, one-hundred twenty porcelain square blocks (552 mm) were prepared and bonding surfaces of each sandblasted. Samples were divided into three groups. The first group (n=40) were etched with buffered HF 9.5% (Ultradent) for 1 min., the second group (n=40) were etched with Iranian APF 1.23% (Kimia) for 10 minutes and the third group (n=40) were etched with Iranian PHA 37% (Kimia) for 1 min. Ultradent silane was applied on the surfaces of half of cases in each group. On the surfaces of half of silane-treated samples unfilled resin was applied and dentin bonding was used on the surfaces of the remaining. Samples without silane were treated in a similar manner. Composite cylinder with 4mm diameter and 2 mm height was bonded to porcelain. Specimens were stored in 37°C distilled water for 24 hours and subjected to 500 cycles. Shear bond strength was measured with an Instron machine and type of fracture was evaluated using a stereomicroscope. Results were analyzed using 3 way ANOVA, Kaplan- Maier and Tukey HSD tests.

Results: Findings showed that PHA and APF roughened the porcelain surface without creating retentive micro undercuts but HF etches porcelain and creates retentive microundercuts. Ultradent silane had no significant effect on bond strength of porcelain- composite. Unfilled resin with Ultradent silane compared with dentin bonding with the same silane is more effective in bond strength of composite- porcelain.

Conclusion: Based on present study, application of Ultradent silane on sandblasted and etched porcelain with PHA or APF cannot be used as an alternative to this silane on sandblasted and etched porcelain with HF.

Prevalence of actinobacillus actinomycetemcomitans and prophyromonas gingivalis in subgingival microflora of patients with aggressive periodontitis

M. Paknejad

Statement of Problem: One of the best ways for treatment of Aggressive Periodontitis (AP) is identification and elimination of etiologic factors specially two microorganisms Actinobacillus actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) in patients harboring them.

Purpose: This study determines the prevalence of Aa and Pg and its correlation with age, sex and the number of family members as well as probing pocket depth (PPD) in active sites of AP patients, referred to department of periodontics, Faculty of Dentistry, Tehran University of Medical Sciences.

Materials and Methods: In this cross sectional, descriptive study, 54 sites (PPD> 5mm) in 15 patients were considered for culture. Marginal gingiva was dried and sampling performed by paperpoint (#30). The selective medium for Aa, was Trypticase Soy Agar-Bacitracin- Vancomycin (TSBV) and for Pg was Brucella agar.Results were analyzed using Fisher and Chi-Square statistical tests.

Results: Thirteen patients or 38 sites (70.4%) were identified as Aa positive and 3 patients or 10 sites (18.4%) were Pg positive. There was no significant relation between the presence of Aa and sex or age (P=0.086). Pg was more prevalent in men compared with women (P<0.0001) but with regard to age there was no statistical difference between men and women. Aa had a significant positive correlation with PPD (P=0.002), which was not true for Pg. In addition, the number of positive sites showed a significant negative correlation with the number of family members.

Conclusion: Based on the present study, the prevalence of Aa in deep pockets in patients with AP is higher than Pg.

Comparison between conventional tomography & radiovisiography methods for assessment of presurgical dental implants

AR. Talaei Pour

Statement of Problem: Computed tomography (CT) has proved to be the most precise method to evaluate the quantity of jaw bones.In recent years, patient dose which is much more greater in CT than conventional methods has attracted more attention, and has brought the idea of using the conventional method in more accurate ways or applying new methods with lower doses.

Purpose:radiovisiography for presurgical evaluation of endosseous implants.

Materials and Methods: measured with the two aforementioned techniques. To determine the magnification factor, an acrylic stent with spherical lead markers with known diameter, has been used. Then in intra-operative phase, this distance was measured directly on the patient’s jawbone. To assess the significance of differences from radiography results and the gold standard the binomial distribution was used.

Results:significant and there was no significant difference between RVG and visual method.

Conclusion:to conventional tomography.

Radiography is the main tool for presurgical assessment of endosseous implants.The goal of this study was the assessment of the accuracy of conventional tomography andDistance between alveolar margin and superior border of mental foramen wasFindings showed that the differences between conventional omography and visual methods wereThis study revealed that the radiovisiography method showed more precise results in comparison

Evaluation of ergonomic postures of dental professions by Rapid Entire Body Assessment (REBA), in Birjand, Iran

J. Nasl Saraji

Statement of Problem: Musculoskeletal disorders (MSDs) are major parts of the occupational diseases in workplaces. Protection from such diseases is dependent on assessment and improvement of job postures by using job analysis methods in ergonomics.

Purpose: This study was aimed to evaluate ergonomic conditions in dental professions by rapid entire body assessment (REBA) in Birjand city and also to assess the relation between MSDS in different parts of the body and work conditions.

Materials and Methods: This study was a descriptive-analytical approach performed on 48 persons working at different professions by using REBA method. The prevalence of MSDs was obtained by using Nordic Musculoskeletal Questionnaire (NMQ). The data were analyzed by independent t-test, Chi-square and Fisher tests with P<0.05 as the limit of significance.

Results: In this investigation, the prevalence of disorders for different parts of the body was as follows: 65% for neck, 60% for back, 38% for shoulders, and 31% for wrist. These disorders were higher in women than men except for the back. There were significant correlation between disorders of femur and foreleg with work history, ankle and sole with body mass index (BMI), and MSDs with work conditions (P<0.05).

Conclusion: It is concluded that the work conditions and postures need to be improved. In addition the level of dental professional education regarding biomechanical hazardous effects as well as correct work conditions and postures should be increased.

Odontogenic keratocyst: a 31- year retrospective study in the oral and maxillofacial pathology department, Faculty of Dentistry, Tehran University of Medical Sciences

N. Eshghyar

Statement of Problem: Odontogenic keratocyst is a developmental odontogenic cyst which arises from dental lamina. One of the important features of odontogenic keratocyst is strong tendency to recurrence.

Purpose: The purpose of this study was the statistical evaluation of age and gender of patient as well as area of involvement in odontogenic keratocysts in the oral and maxillofacial pathology department of dental faculty of Tehran University of Medical Sciences from 1971-2002. Materials and Methods: This study was a cross sectional, descriptive one. Medical records were reviewed and variables such as age, gender and site of involvement were recorded. The data were analyzed with SPSS software.

Results: The relative frequency of odontogenic keratocyst was 36%. 66% of cysts were in men and 34% in women. 68% of lesions affected the lower jaw and 32% the upper jaw. Regarding the site of involvement, 48% of lesions involved the molar region of mandible and 42%, the anterior part of maxilla. The occurrence of keratocysts was higher in this sites. Most of the cases were diagnosed in the third decade.

Conclusion: Based on the findings of this study, odontogenic keratocyst was more prevalent in men, mandible and the third decade. The posterior part of mandible and anterior region of maxilla were involved most frequently.

Effect of two bleaching agents on enamel morphology: a SEM study

M. Ghavam

Statement of Problem: Bleaching materials are able to change the surface morphology as well as mineral and organic content of tooth structure. Considering that bleaching is done for aesthetic purpose, awareness of the possible effect of these materials on hard tissue is important, because it may affect the restorative treatments.

Purpose: The aim of this study was comparing the effect of two bleaching materials, Kimia and Ultradent both containing 35% H2O2, on tooth enamel by SEM.

Materials and Methods: Five intact central incisors were cut into three sections vertically and each part was randomly divided into three groups. Group 1 (control), without any bleaching. Group 2, bleached with Kimia 35% H2O2. Group 3, bleached with Ultradent 35% H2O2. Each tooth served as its own control. Then the samples were observed by SEM with 250 and 500 magnifications.

Results: In the control group some scratches and small white grains were observed which seems to be the result of mastication trauma and pumice powder. In the other groups, morphologic changes like increased surface roughness, deepening of cracks, rod exposure and presence of new cracks were observed. The two experimental materials did not differ in these regards.

Conclusion: It seems that both studied materials have limited destructive effects on tooth enamel which seems to be of no clinical importance.

Biocompatibility evaluation of Minalux and VeraBond2 in-vitro

A. Mirfazaelian

Statement of Problem: One of newly presented base metal alloys (Minalux) is produced according to VeraBond2 alloy (Ni- Cr base) composition. Several studies showed that, cytotoxicity of base metal alloys can be occurred due to corrosion and element release.

Purpose: This study evaluated the biocompatibility of these two base metal alloys in three steps: as cast, after polishing and after porcelain firing cycles. Release of Ni and Cr ions were measured to determine if there is any difference between these two alloys.

Materials and Methods: Samples of two base metal alloys were subjected to Neutral Red Assay, MTT Assay and Trypan Blue for biocompatibility tests. Fibroblast Balb/c 3T3 cells were used for cell culture. Samples were contacted directly with cells in 37ºc and 5% Co2 concentration for 72 hours. Teflon samples were used as negative control. ANOVA test was used to compare different groups of two alloys. In addition, the release of Ni and Cr ions in to saline solution was measured by means of atomic absorption spectrometry.

Results: MTT and Trypan Blue didn’t show any significant difference between Minalux, VeraBond2 and Teflon. Neutral Red Assay showed no significant difference between these two base metal alloys but as cast group was higher in cytotoxicity in comparisons with polished and firing groups in both two alloys. Release of Cr ion was non detectable (Cr < 1 PPB) but Ni ion was measured and Ni release was significantly different in as cast groups (P=0.007) of two alloys.

Conclusion: There is no significant difference between cytotoxicity of two base metal alloys and polishing and firing can decrease cytotoxicity of both alloys.

Histologic and histomorphometric evaluation of osteogenesis induced by octacalcium phosphate (OCP) combined with bone matrix gelatin (BMG) in rat skull defects

Ag. Sobhani

Statement of Problem: Several methods are used to enhance bone repair and new bone formation, and bone matrix gelatin (BMG) is recently introduced.

Purpose: The purpose of this histologic and histomorphometric study was to assess the osteogenic potential and the quantity of new trabecular bone formation after implantation of OCP and BMG alone and in combination into the cranial defects in rat.

Materials and Methods: In this experimental study, 100 young male Sprague Dawley rats (5-6 weeks age and 120-150gr weight) were divided into four groups randomly. A full thickness standard trephine defect 5mm in diameter was made in the rat’s parietal bone, and 5mg of OCP, BMG alone and in combination were implanted into the defects. No OCP and BMG particles were implanted in control group which was otherwise treated identically. On the 5th, 7th, 14th, 21st and 56th days after implantation, the rats were killed and bone samples collected. After processing the samples by routine histological procedures, 5µm thick sections of bone were cut and stained with Haematoxyline & Eosin (H&E) and Alcian Blue and studied histologically and histomorphometrically using light microscope and eyepiece graticule. The amount of newly formed bone was quantitatively measured by the use of histomorphometric methods. Data were analyzed with SAS statistical package using ANOVA and Duncan tests.

Results: In the experimental groups, the new bone formation was initiated from the margin of defects during 5-14 days after implantation. During 14-21 days after implantation, bone marrow cavities and bone marrow tissues in newly formed bone were seen. By the end of the study, the newly formed bone increased and was relatively matured and almost all of the implanted materials were absorbed. In control group, at the end of the study, a few clusters of new bone were seen near to the defect margins and host bone. The histomorphometric analysis indicated statistical significant differences in the amount of newly formed bone between the experimental and control groups (P<0.05).

Conclusion: Implants of OCP/BMG appear to stimulate bone induction and new bone growth in bone defects greater than the other groups and these biomaterials could be used in the repair of cranial bone defects in clinical situations.

Measuring the degree of conversion of ScotchBond MP Plus Adhesive, Single Bond, Prompt L-Pop and an experimental bonding resin

TS. Jafarzadeh Kashi

Statement of Problem: The quantity of remaining unreacted double bonds may be a significant factor pertaining to the mechanical, physical and chemical properties of restorative resins. Insufficient polymerisation within the hybrid layer may cause significant differences in the quality of this layer, and act as a reservoir for monomer release thus increasing cytotoxic potential.

Purpose: The aim of this study was to measure the degree of conversion of three generations of 3M dentin bonding agents and an experimental dentin bonding agent

Materials and Methods: The quantity was determined from the transmission IR-spectrum of the materials before and after polymerization. ScotchBond MP plus adhesive, SingleBond, Prompt L-Pop, and an experimental dentin bonding were used to measure degree of conversion. Six repetitions of each bonding were investigated. Time of light curing was 120s. Kruskal-Wallis and Mann-whitney test were used to compare groups with P<0.05 as the limit of significance.

Results: The results showed a significant difference between groups (P<0.01). A trend of increasing in Singlebond conversion obtained in comparison with ScotchBond MP plus adhesive, Prompt L-Pop and experimental dentin bonding. The degree of conversion was not statistically significant among the other dentin bondings. No significant difference was found between conversion of the experimental dentin bonding and ScotchBond MP plus adhesive (P=1.00) with P<0.05 as the limit of significance.

Conclusion: Dentin bonding technology continues to evolve toward simpler systems. However, Prompt L-Pop as a self-etching adhesive does not show the trend of increasing the degree of conversion. However, the performance of these simpler systems must be further investigated.

Comparison of shear bond strength between unfilled resin to dry enamel and dentin bonding to moist and dry enamel

E. Yasini

Statement of Problem: The use of dentine bondings on enamel and dentin in total etch protocols has recently become popular. Unfilled resin is hydrophobic and dentin bonding is hydrophilic in nature. This chemical difference could be effective in enamel bonding process. Purpose: The aim of this study was to compare the shear bond strength of unfilled resin to dry enamel and dentin bonding to dry and moist enamel.

Materials and Methods: In this experimental study, a total of 30 incisor teeth were used. The specimens were randomly assigned to three groups of 10. 37% phosphoric acid etchant was applied to the enamel surfaces in each group for 15 seconds, rinsed with water for 20 seconds and dried for 20 seconds with compressed air in groups one and two. After conditioning, group 1 received unfilled resin (Margin Bond, Colten) and group 2 received dentin bonding (Single Bond, 3M) and in group 3 after conditioning and rinsing with water, a layer of dentin bonding (Single Bond) was applied on wet enamel. The enamel and dentin bonding were light cured for 20 seconds. A ring mold 3.5 mm in diameter and 2 mm height was placed over the specimens to receive the composite filling material (Z100, 3M). The composite was cured for 40 seconds. The specimens were thermocycled and shear bond strengths were determined using an Instron Universal Testing Machine. The findings were analyzed by ANOVA One-Way and Tukey HSD tests.

Results: Shear bond strength of dentin bonding to dry enamel was significantly less than unfilled resin to dry enamel (P<0.05). There was no significant difference between the bond strength of dentin bonding to moist and dry enamel. In addition bond strength of dentin bonding to wet enamel was not significantly different from unfilled resin to dry enamel.

Conclusion: Based on the findings of this study, it is suggested that enamel surface should remain slightly moist after etching before bonding with single bond but when using unfilled resin, the enamel surface should be kept dry.

Interrelationships of endodontic- orthodontic treatments

S. Khedmat

The purpose of this article was reviewing the literature related to the mutual effects of endodontics and orthodontics on each other providing documented information that can be used by dentists in clinical practice. The effect of orthodontic treatment on the dental pulp and its role in root resorption, the influence of previous trauma to the tooth and endodontic treatment in orthodontic tooth movements and root resorption, recommendations regarding endodontic treatment during orthodontic tooth movement and the role of the orthodontic forces in provision and outcome of endodontic treatment are being discussed. The effect of the orthodontic tooth movement on the pulp is focused primarily on the neurovascular system which can cause degenerative and/or inflammatory responses in the dental pulp. Although, most of these changes are considered reversible, it seems that teeth with complete apical foramen and teeth subjected to previous insults, such as trauma, caries, restorations and periodontal diseases are more susceptible to pulpal irreversible changes. Teeth with root canal treatment that are well cleaned shaped, and three- dimensionally obturated, exhibit less propensity to apical root resorption during orthodontic tooth movement. This outcome depends on the absence of microleakage for bacterial ingress. A traumatized tooth can be moved orthodontically with minimal risk of resorption, provided that the pulp has not been severely injured (infection or necrosis). If there is evidence of pulpal demise, appropriate endodontic treatment is necessary prior to orthodontic treatment .If a previously traumatized tooth exhibits resorption, there is a greater chance that orthodontic tooth movement will enhance the resorptive process. If a tooth has been severely traumatized (intrusion, avulsion) there would be a greater incidence of resorption with tooth movement. It is recommended that teeth requiring root canal treatment during orthodontic movement be initially cleaned and shaped followed by the interim placement of calcium hydroxide. Final canal obturation with gutta-percha should be accomplished upon the completion of orthodontic treatment. Endodontically treated teeth can be moved orthodontically similar to teeth with vital pulps. In case of endodontic procedures like apexification, there may be no need to delay the orthodontic treatment.