Journal of Dentistry, Shiraz University of Medical Sciences
Volume:6 Issue: 1, 2006

Statements of Problem: Natural head position (NHP) provides the key for meaningful cephalometric analyses because an extracranial reference line is used instead of intracranial reference lines, known to be subject to considerable biological variation in their inclination. In many instances lateral cephalograms are taken or have been taken with conventional technique. The aim of this study was to compare the accuracy of some conventional analyses in diagnosis of antero-posterior jaw relationship. This study was based on tracing of 60 lateral cephalograms that were taken with NHP technique. In the sample, there were 22 boys and 38 girls aged between 10 to 13 years old. Twenty of the x-ray films were normal occlusion. Others were class II and III, 20 of each. All cephalograms were taken in the Department of Radiology of Mashhad University Dental School. At first lateral cephalograms were analyzed with NHP method as gold standard and according to the results, patients were classified by angle classification coincided with skeletal categories. Then lateral cephalograms were analyzed with Downs, “Wits”, Sassouni and Steiner methods. Finally, by using SPSS software, the validity criteria including sensitivity, specificity, positive predictive value, negative predictive value as well as their accuracy were compared to each other. This study showed that Downs and “Wits” analyses were the most accurate methods in diagnosis of class I cases. Furthermore, the sensitivity of downs analyses for class I patients was the highest. But the most accurate analyses in diagnosis of class II jaw relationship were downs and Steiner methods and for class III jaw relationship was downs analyses. If analyses for evaluation of sagittal relationships of the patients are needed, downs analyses is suggested because this method had the most correlation with NHP analyses.

Statements of Problems: Head and neck squamous cell carcinoma is the sixth most common cancer worldwide. Inactivation of one or more components of the P53 network is a common event in human neoplasia. In head and neck carcinoma, disability of P53, occurs in a high proportion of cases by mutation in the P53 gene. Cause of inactivation, such as the presence of human papilloma virus (HPV) has also been recognized. The aim of this study was to examine co-incidence of human papilloma viruses type 16.18 and P53 alteration in oral squamous cell carcinoma. Of 42 oral tissue specimen (36 oral squmous cell carcinoma and 6 oral verrucous carcinoma) including 25 men and 17 women which were visited in Isfahan University, School of Dentistry in 1369-1383, multiple serial sections from formalin fixed, paraffin embedded tissues were prepared. Immunohistochemical detection of P53 protein was carried out by a standard Avidin-Biotin peroxidase procedure. Standard PCR analysis was used for detection of DNA HPV 16 and 18. The data were analyzed with Chi-Square and Fischer Exact tests. General HPV sequence was detected in 21 out 42 (50%) tumor specimens. HPV 16 and 18 sequences were detected in 11 of 42 (26.2%) tumor specimens. Over expression of P53 was observed in 23 of 42 (54.8%) oral cancers. Ten of the 21 HPV Positive tumor specimens showed alterations in P53 protein expression. In spite of no significant correlation between observation of general HPV genome and P53 alteration, a significant correlation between HPV 16 and 18 and P53 alteration existed. In present study, we could not show any significant correlation between general HPV genome and intensity of P53 expression. A remarkable correlation between HPV 16 and 18 and over expression of P53 protein was observed. So, the results of this study remained controversial and we suggest a more precise modified procedure to be performed on this subject. So, frozen technique and more samples would be necessary for further study in future.

Nowadays transplantation is widely used to manage end organ failure, the way that saves patient's lives and increases their survival rate. But it has some complications such as posttransplant malignancies; one of them is posttransplant lymphoproliferative disorder (PTLD). PTLD is more prevalent in children than in adults and it occurs from months to years after transplantation with the peak of 3-7 months. The incidence of PTLD after heart-lung transplantation is the most (9.4%) and after kidney transplantation is the least (1%). The common sites of PTLD involvement include abdominal region (32%), bone marrow (25%) and other sites including head and neck (43%). PTLD is related with immunosuppression caused by administration of immunosuppressive agents and is mostly accompanied by the proliferation of Epstein-Barr virus. Clinical presentation of PTLD varies from a self limiting mononucleosis to a generalized lymphoid infiltration or even a lymphoma. Management of PTLD includes reduction of immunosuppression, using anti CD20 antibody, antiviral drugs, chemothrapy and radiotherapy which are not so efficient. It's prognosis is poor and has 54% mortality rate. Clinical features of PTLD in head and neck region are cervical lymphadenopathy, generalized gingival hyperplasia with erythema, swelling, cyanotic foci and chronic mucosal ulcers; so this neccessitizes referring of a patient with such signs and symptoms or other suspicious conditions in the head and neck to a dentist for early diagnosis and biopsy. This article reviews PTLD with emphasis on oral manifestations and head and neck involvement.

Nowadays, restoring teeth with minimal sacrifice of sound tooth structure forms the basis of restorative practice. To achieve this concept, adhesives should essentially provide strong and durable bonding. Bonding to enamel is known to be more stable over time, but stability of contemporary dentin bondings are still questionable. Although their short term bonding effectiveness are sufficient, nowadays, there is an obvious trend in the development of adhesives with a simplified and easier application procedure but durabilitity of simplified adhesives in comparison to conventional adhesives is questionable. Impregnation of water through nanometer-sized prosities within hybrid and adhesive layer as nanoleakage is considered very detrimental to bond integrity and durability. Impregnation of water lead to hyrolysis (break up covalent bonds) and plasticizing of resin components due to reduction of the frictional forces between the polymer chains. Penetration and extension of water into adhesive interface is related to the permeability of simplified adhesives that behave as permeable or semipermeable membranes after polymerization and do not provide any hermetic seal on the prepared dentin. So, two-step etch & rinse adhesives with combination of primer and adhesive resin, are more susceptible to water sorption due to less-optimal hybridization and residual solvent and these are susceptible to water degradation due to the presence of hydrophilic monomer in final cured adhesive layer compared to three step etch & rinse. The surrounding resin-enamel bond plays a protective role against degradation. One-step self-etch adhesives are susceptible to water sorption and osmotically- induced water movement from dentin to bonding surface, water-tree formation and hydrolytic degradation due to the presence of acidic, hydrophilic monomer and the residual water (as essential solvent). During solvent evaporation, the monomer/water ratio may change and subsequently result in phase separations and blistering. Therefore the hydrolytic stability of cured adhesives is of crucial importance. The best way to achieve this goal is to apply a solvent-free, neutral–pH, hydrophobic adhesive resin layer in a separate step. Three-step etch & rinse adhesives remain the “gold standard” in terms of adhesion durability. Any kind of simplification in the clinical application procedure results in a loss of bonding effectiveness. Only two-step, self-etch most adhesives closely approach this standard, and have additional clinical benefits.

Statement of Problem: Infection control is the main step of prevention in dentistry. Effects of disinfectant solution must be evaluated in this process. The aim of this study was to evaluate the disinfecting effect of Deconex (solarsept), Cidex, and Micro 10 on high and low speed handpiece surfaces after cavity preparation. In this experimental study, 105 specimens were obtained from surfaces of high and low speed handpieces after cavity preparation by sterile swab and were divided into 7 groups. Each group contained fifteen specimens which were carried to thioglycolate media. Samples were incubated and remained for 48 hours at 37oc. Microorganisms were cultured in different media, and the rate of microbial growth were calculated. Following the various stages of investigation, it was found that all specimens from the surfaces of high and low speed handpieces, after cavity preparation, were infected, but no microbial growth and colony formation were detected after disinfecting the surfaces by disinfectants solutions used in the study. By evaluation of various sampling stages and microbial cultures in this study, it was concluded that the three disinfectants were able to destroy specific kinds of microorganisms after cavity preparation procedures, if they were provided and used by manufacturer instructions in order to decrease infection transmission.

Statement of Problem: Extraction of mandibular third molar is one of the routine surgical procedures in dentistry. Disestesia because of damage to sensory bundles of inferior-alveolar nerve is one of the complications which may happen following this surgery. Panoramic radiograph is the method which, most of the dentists commonly apply for the assessment of the relationship between the tooth and canal. However, this technique can show a two dimensional view of the site. In this study we compared tomography which showed the third dimension with, panoramic in determining the position of the tooth relative to canal. Sixty tomographs and panoramic radiographs of 60 impacted mandibular 3rd molar of patients being 25 years old or more were evaluated. The mean of the vertical distance of the tooth apex to superior border of mandibular canal was measured in both radiographs and then means were compared together. The mean of horizontal distance was measured in tomographs compared with zero in panoramic. Buccolingual location of the canal relative to the tooth was determined in tomographs. The mean of vertical distance in tomographys and panoramic views was 2.7 mm and 1.1 mm respectively. Both of the differences were significant. About 39% of canals were buccal, 19.5% were lingual and 41.5% were inferior to the tooth. The difference between panoramic radiography and tomography in determining the vertical distance of the tooth apex to superior border of mandibular canal was significant. Tomography can show buccolingual relationship of the canal relative to the tooth and distinguish the roots superimposed on canal that seem tangent from real tangent roots.

Statement of Problem: Because commonly used obturating materials can not provide hermetic seal against saliva and microorganisms in the root canal system, thus it has been suggested that the use of intraorifice sealing of Gutta percha obturated root canals to prevent coronal micorleakage. The purpose of this study was to evaluate coronal micorleakage of four materials used as an intraorifice plug. After cleaning, shaping and conventional obturation of 86 extracted human single root canal and, a 3 millimeters of the gutta percha was removed from the coronal aspect of the root canal and replaced with one of the four filling materials: MTA, Glass Ionomer (GI), Coltozole and Amalgam. Microleakage was evaluated by using of staining penetration methods with Indian ink and after clearing of the specimens, the linear dye penetration was measured. The mean of linear dye penetration for each group was compared by the ANOVA and Post Hoc test. The results showed that GI group had significantly the most leakage and the other experimental groups of Amalgam and Coltozole significantly sealed better. On the other hand, the MTA group had significantly the least leakage. The result of this study showed that although the three experimental materials (Amalgam, Coltozol and MTA) except GI were able to decrease the coronal microleakage, but none of them were able to prevent microlaeakge completely. So, use of orifice plug to reduce coronal microlaekage which is one of the important causes of failure in endodontic, seems to be useful.

Statement of Problem: Fixed orthodontic appliances are considered to be a clinical risk factor in terms of gingival and enamel integrity, because of plaque accumulation around the bracket bases which increases the levels of microorganisms. Although chlorohexidine significantly reduces plaque accumulation, but its side effects prevents its common use. The purpose of this in vivo study was to compare the antibacterial effects of two herbal mouthwashes of persica and matrica with chlorhexidine in fixed orthodontic patients. A total of 68 orthodontic patients of 13-19 years old (who referred to a private clinic in 2002) with good oral hygiene were randomized into 4 groups. Group 1 (control) used water, group 2 used Chlorhexidine, group 3 used Persica and group 4 used matrica, twice a day for 3 weeks. The number of all bacterial colonies around the ring elastics of the upper canine and premolar growing in the culture media were counted before (T1) immediately after (T2) and 3 weeks after (T3) the use of the mouthwashes and water in all 4 groups and analyzed. Chlorhexidine, Persica and Matrica mouthwashes significantly reduced the amount of bacteria around the brackets immediately and after 20 days after their use. The intergroup comparison showed that persica and matrica at T2 and T3 had significant differences with chlorhexidine group. So, Chlorhexidine was the most effective antibacterial mouthwash in T2 and T3. Persica and Matrica groups showed no significant differences both in T2 and T3, but had significant difference with the control group. The use of herbal mouthwashes such as Persica and Matrica in orthodontic patients can significantly reduce the amount of microorganisms around the bracket bases without any side effect such as tooth discoloration which is seen with Chlorhexidine.

Statement of Problem: The most common major defect of the lip and palate is clefting. Clefting occurs due to failure of fusion between embryologic structures. Tooth size abnormalities are common in these patients. This study was performed to determine the tooth size in cleft lip and or patients and compare with normal individual. This study was carried out on 51 pretreatment orthodontic records of the cleft lip and or palate patients and compared with 276 normal individuals. These subjects were in acceptable age for determination of the mesiodistal width of the teeth. The greatest mesiodistal width of all permanent teeth on each model was obtained except the second and third molars. The measuring was done by digital calliper with 0.01 mm accuracy. The collected data were analyzed by SPSS software and t. test. This study showed that there was no asymmetry in tooth size between cleft and normal sides of the maxillary arch. The upper teeth in cleft patients were smaller than the upper teeth in normal patients and there was a significant difference. The lateral incisor and first premolar in females and the central incisor, second premolar and first molar in males were smaller in the cleft patients than normal groups in the mandibular arch. We concluded that: 1) tooth size of the maxillary arch in cleft patients was smaller than non-cleft subjects. 2) There was no significant difference between cleft and non-cleft sides in tooth size. 3) Tooth size in mandibular arch of cleft patients was affected less than maxillary arch.

Statement of Problem: Difficulties in sterilizing impressions by traditional methods have led to chemical disinfections as an alternative, and some studies have shown that some methods may adversely affect impressions. This study evaluated the effectiveness of 5.25% sodium hypochlorite spray and immersion disinfection methods on irreversible hydrocolloid impressions (Iralgin alginate). In this study, twenty normal individuals were randomly selected. Impressions were made by a sterile tray from the maxillary arch and then were contaminated with the following organisms: staphylococcus aureus, streptococcus mutans, β-hemolytic streptococcus type A, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. Impressions were cut and divided into three sections anterioposteriorly and longitudinally. Then, sections were randomly placed in three groups as 1) control (without disinfection), 2) immersion and 3) spray. Then, the provided samples (pieces) of impression materials were cultured and microbial count of the three groups were compared. All of agar models from 20 alginate pieces in control group showed a positive microbial growth. Ten agar models form 20 alginate pieces which were disinfected by spraying method, showed also positive microbial growth and only 2 agar models out of 20 alginate pieces which were disinfected by immersion method showed a positive microbial growth. The mean number of organisms recovered form the surface of the impressions in control group was 3.52×108 CFU/ml while in spay and immersion groups it was 132217 CFU/ml and 1915 CFU/ml respectively. According to the results of this study, disinfection by immersion method with 5.25% sodium hypochlorite was more effective than the spray method.

Bifid mandibular canal is a rare condition that has been reported by researchers in different countries. According to the present data, comprehensive evaluation of such cases has not been yet performed in Iran. It seems that examination of patient with bifid mandibular canal has its own scientific importance. This is a case of a 35 years old man who referred to Shiraz Dental School for routine dental treatment. Panoramic radiograph of the patient showed a bilateral ascending accessory manibular canal. According to the complications of such an anomaly like inadequate anesthesia in the affected side, infringing of wisdom teeth in the accessory canal, bleeding, traumatic nuroma, etc and due to rarity of such cases this case was selected to be reported as a case-report.

Statement of Problem: Congenital heart disease is the most common disposing factor to bacterial endocarditis. Since the people with cardiac disease are in high risk of caries and some microorganisms of endocarditis are due to streptococci (caries initiation), good dental and oral health in these people are very important. The purpose of this study was to determine the parent’s knowledge about antibiotic prophylaxis before dental procedure and dental health (dmft/DMFT) of the children at risk of endocarditis. This is a cross-sectional descriptive analytical study performed on 84 people subjects (38 M, 46 F) being 2-17 years old and at risk of endocarditis in Amirkola and Shahid Beheshti Hospital in Babol. After clinical examination of the patients and completing of the questionnaires, findings were analyzed according to SPSS program and Chi-Square test. The percentage of parents who understood the meaning of ‘heart infection’ was 42.9% those, who knew the possibility of endocarditis occurrence to be caused by a dental procedure was 57.1%, those who understood the requirement for antibiotic cover before dental treatment was 16.7%, and those who understood the importance of a good oral health to prevent infective endocarditis was 60.7%.Regarding oral health behaviour, 51.2% of children brushed their teeth at least once a day and 48.8% did not brush their teeth or brushed irregularly. Only 2.4% of children referred a dentist every six months and 44% had never visited a dentist before. 26.1% of subjects were free of caries and the mean of dmft was 1.86±2.47 and for DMFT was 2.23±2.97. The parents’ knowledge about the importance of dental health and its role in prevention of endocarditis was low. Absence of caries in these children was low making them susceptible to bacterial endocarditis.

A case of chondrosarcoma involving the maxilla is reported. The salient points of the presented case include; diagnostic and pathologic processes, radical surgery and simultaneous chondral graft and finally long terme follow-up.The most important lessen to be learned from this report, first is that the patient referred too late in the course of the disease, thus, the tumor was progressively involved entire maxilla ultimately. In the literature, in more knowledged countries usually the size of tumor is reported to be between 2-4 cm. Secondly, Histophthology study plays an important role in the survival rate and final patient’s outcome. The microscopic differential diagnosis of chondrosarcom from osteoma, chondroma, osteoid osteoma, fibro-osseous lesions and osteogenous sarcoma is an important and often difficult consideration. The most oral and maxillofacial pathologists believed that the specimens is better to be large and multiple, so provide a more suitable overview by microscopic study.Finally wide resection of the chondrosarcoma is the most acceptable choice of treatment. The role of radiotherapy and chemotherapy as an adjunctive treatment remain controversial. On the basis of the extremely aggressive clinical behavior of these tumors, the survival rate is rather poor.

Statement of Problem: Canal preparation is one of the most important and time- consuming steps in endodontic treatment of primary teeth. Regarding the difficulties in behavior management of some children, rotary (nickel-titanium) files proved more facilities and speed and hence more success in the root canal treatment of primary teeth. The purpose of the present study is comparison of the success rate and cleaning time of pulpectomy in necrotic primary molar teeth using manual and rotary instruments. In this study which is an interventional in vivo clinical trial, 40 patients, mean age 5.7+0.92, were randomly selected and divided into two equal groups (I, II). In the first visit, pulpotomy of the necrotic teeth was done for all of the cases. In the second appointment after local anesthesia and isolation of the teeth with rubber dam, preparation of the canals was done with pro-taper nickel-titanium files (S1, S2, F2) in the first group and with stainless steel manual K-files (10-30) in the second group. The total time needed for debridement was calculated exactly by chronometer. The canals were then filled with ZOE by using lentulo spirals and periapical radiography was prepared for all of the cases. The patients were followed-up in 3 and 6 months intervals and the statistical analysis were done by Non-Parametry Mann-Whitney test. The success rates of manual and rotary instruments were 85% and 90% respectively after 3 months. The success rate of the two groups (I, II) was 100% after 6 months follow-up and all of the signs and symptoms including pain, abscess, fistula and perapical radiolucency disappeared. The time needed for canal preparation was calculated 4.12 minutes (251.75+32.58 seconds) with Pro-Taper and 9.21 minutes (563.05+ 70.03 seconds) with manual instruments. The difference was statistically significant. The success rate of manual and rotary instruments was 100% in both groups but the preparation time (which is an important clinical factor for patients management) significantly reduced using rotary instruments. Hence, pulpectomy of the primary teeth using rotary instruments (Pro-Taper files) is recommended for root canal treatments in children.

Statement of Problem: The main goal of root canal therapy is total elimination of bacteria from root canals. Studies have shown that the cleaning and shaping of root canals can not complexly eliminate these bacteria from the root canals. Obturation may kill the bacteria due to entrapment of them into the canals and prevent their access to nutrition. On the other hand, using of Ca (OH)2 before obturation may help to promise a better reduction of bacteria from root canals. The purpose of this study is an in vitro evaluation of antibacterial effect of obturaiton solely, or with using Ca (OH)2 as an intracanal dressing on E.F. in infected human root canals. For this experimental study, 50 single rooted human teeth without significant curvature were chosen. After cutting the crowns and preparing root canals, the samples were sterilized and then contaminated with Entrococcus faecalis bacteria for 5 days. The samples were divided randomly into 4 groups. The first experimental group which included 20 teeth, were filled by Ca (oH)2 for one week before obturation by lateral condensation technique. The second experimental group (20 samples) were obturated by ZOE sealer and gutta percha with lateral condensation for 2 weeks. Five roots considered as positive control were contaminated with bacteria but were not obturated, and 5 other roots were obturated after sterilization without contamination as negative control group. All samples were incubated in 35oC and 10% moisture for 2 weeks. Then the coronal and apical part of roots were removed and the dentin powder were collected from the middle parts by drilling the canals in sterile condition. Two mg of dentin powder was weighed from each root and cultured in blood agar for 48 hours. The results were recorded and compared with each other by Chi-Square test. All samples were positive in culture of positive control group, and negative in culture of negative control group. First experimental group did not show any positive growth after the incubation period and there was only one positive culture in the second experimental group. The findings of this study illustrated no significant difference between the two experimental groups. In other words, the obturation of canals with gutta percha and sealer merely could kill the E.F. in the infected root canals and application of Ca (OH)2 before obturation was not necessary for disinfection of canals.