Dental Research Journal
Volume:9 Issue: 3, May 2012

Accumulating evidence suggests that self-renewal and differentiation capabilities reside only in a subpopulation of tumor cells, termed cancer stem cells (CSCs), whereas the remaining tumor cell population lacks the ability to initiate tumor development or support continued tumor growth. In head and neck squamous cell carcinoma (HNSCC), as with other malignancies, CSCs have been increasingly shown to have an integral role in tumor initiation, disease progression, metastasis, and treatment resistance. In this article, the author summarizes the current knowledge of the role of CSCs in HNSCC and discusses the therapeutic implications and future directions of this field.

Hypodontia is the most common dental anomaly and might cause clinical complications. The aim of this study was to assess the prevalence and pattern of congenital missing in the permanent dentition dentition (excluding third molars), among Iranian orthodontic patients. In this descriptive cross-sectional study, all approved panoramic radiographs of 3374 orthodontic patients (aged 10 to 20 years old), who had visited the Orthodontic Departments of all Tehran Dentistry Universities and 10 private clinics during the years 1999 to 2009 were investigated, to establish the prevalence of hypodontia in the permanent dentition (excluding third molars). The data were analyzed using a chi-square test (α = 0.01). Included were 2012 female and 1362 male patients. The prevalence of hypodontia was 5.21% (5.86% in females, 4.25% in males). The difference between the genders in terms of missing teeth was not significant (P = 0.202). A total of 298 teeth were missing (166 in females, 132 in males). The average of missing per individual was found to be 1.69 (1.40 missing for each girl, 2.32 for each boy). There was no significant difference between the number of missing teeth in males and females (P = 0.160). The most common missing teeth were maxillary lateral incisors (37.2%), mandibular second premolars (22.1%), and mandibular central incisors (10.7%). In both unilateral and bilateral hypodontia cases, the maxillary lateral had the highest prevalence of missing, followed by the mandibular second premolar. Missing was significantly more frequent (P = 0.001) in the maxilla (5.3%) compared to the mandible (3.5%). Out of every 20 Iranian orthodontic patients, one might have some missing permanent teeth, needing early attention. Hypodontia was more prevalent in females (though not significantly) and in the maxilla. Although more females were affected, the number of missing per individual was greater in males.

Reactive lesions of the oral cavity are non-neoplastic proliferations with very similar clinical appearance to benign neoplastic proliferation. This similarity is troublesome in the differential diagnosis. The aim of this study was to determine the frequency and distribution of oral cavity reactive lesions. The study was a retrospective archive review. The medical records of 2068 patients with histopathologic diagnosis of oral cavity reactive lesions were studied. The patients’ clinical data were registered and evaluated retrospectively. The obtained frequency of patients’ age, gender, and anatomic location were analyzed. Descriptive statistics were used for evaluating the registered data. Peripheral giant cell granuloma was the most prevalent lesion (n=623, 30.12%). This was followed by pyogenic granuloma (n=365, 17.65%), epulis fissuratum (n=327, 15.81%), irritation fibroma (n=288, 13.93%), cemento-ossifying fibroma (n=277, 13.40%), inflammatory fibrous hyperplasia (n=177, 8.56%), and inflammatory papillary hyperplasia (n=11, 0.53%). The age ranged from 2 to 85 years, with a mean of 39.56 years. The lesions were more common in males (n=1219, 58.95%) than in females (n=849, 41.05%). Attached gingiva with 1331 (64.36%) cases was the most frequent place of reactive lesions. Peripheral giant cell granuloma was the most prevalent reactive lesion of the oral cavity. The reactive lesions were more common in males, gingival, and the third decade. Some differences have been found between the findings of the present study and previous reports.

Fungi may play a key part in periradicular diseases. The aim of this study was to evaluate and compare the antifungal properties of two root-end filling materials, ProRoot Mineral trioxide aggregate (MTA) and MTA-Angelus, against Candida albicans using tube-dilution test. The antifungal properties of ProRoot MTA and MTA-Angelus against C. albicans was assessed at 1, 24, and 48 hours following administration of two concentrations of the antifungal agents (50 and 100 mg/ml). A total of 50 culture wells were divided into four experimental groups (Freshly mixed MTA, Freshly mixed MTA-Angelus, 24-h set MTA, and 24-h set MTA-Angelus) and two control groups. Each well was prepared for one specific agent with a specific concentration. For the set groups, the mixture was prepared and left for 24 hours. One milliliter of suspension of fungal colonies with concentration of 104 CFU/ml was then added to the mixtures in each well. All wells were incubated at 37°C and assessed at 1, 24, and 48 hours. This observation was based on the turbidity of the suspension in the tubes. At each time point, 0.02 ml of each suspension was cultured on a Sabouraud dextrose agar plate to confirm C. albicans growth. The results were analyzed using Kruskal-Wallis test. Although all fresh and set samples were incapable of killing C. albicans at 1 hour, they demonstrated fungicidal ability on agar plates at 24 and 48-hour time points. MTA-angelus proved to be an effective antifungal agent compared to ProRoot MTA at concentrations of 50 mg/ml and 100 mg/ml.

Periodontal subgingival pathogens affect local and systemic immune responses and initiate an acute phase systemic inflammatory response characterized by the release of C-reactive proteins (CRPs). This study has been carried out to evaluate the serum concentration of CRPs, which can be used as a marker of periodontal disease as well as a risk indicator for cardiovascular diseases. In a retrospective study a total number of 45 subjects were selected from the outpatient department of periodontics a mean age of 40 years. Based on the periodontal status, the subjects were divided into 3 groups of 15 subjects each. Group I: Control group [with attachment loss (AL) ≤ 2 mm and pocket depth (PD) < 3 mm], Group II: Generalized aggressive periodontitis (AL ≤ 5 mm), Group III: chronic periodontitis (AL ≥ 2 mm, PD ≥ 5 mm), which includes moderate and severe periodontitis. The clinical parameters recorded were plaque index,gingival index, bleeding index, probing PD, and clinical attachment levels and scoring was done on 6 surfaces of all teeth. For the CRP assessment, blood samples were collected from subjects at the time of clinical examination. Analysis of covariance was used for comparison of mean values between the groups to adjust the ages (P value < 0.05). Overall, the mean CRP levels were high in subjects with generalized aggressive and chronic periodontitis compared with controls. This was found to be statistically significant. A statistically significant difference (P = 0.012) was found in the CRP level between groups I and II and between groups II and III, and between groups I and III. The results of the present study indicated an increase in serum CRP levels in subjects with generalized aggressive periodontitis and chronic periodontitis as compared with the controls.

The possibility of impaired antioxidant status and so increased oxidative damage in periodontal disease is being conjectured. The present randomized controlled study was carried out with the objective of analyzing the activity of superoxide dismutase enzyme and thiol antioxidants in gingival crevicular fluid (GCF) and saliva as indicators of response to periodontal therapy. Subjects were screened and randomly divided into three groups: 23 periodontally healthy controls, 24 with gingivitis, and 23 with periodontitis. Based on the clinical attachment levels, the periodontitis group was further divided into subgroups, including mild, moderate, and severe periodontitis. GCF and saliva samples were collected for estimation of superoxide dismutase and thiol antioxidant concentrations at baseline and 15 days after nonsurgical treatment. Intragroup comparisons were statistically analyzed using repeated measures analysis of covariance (P value <0.05). Superoxide dismutase was present in greater quantities in the GCF compartment (100.32±3.67 U/0.5 mL) than in saliva (39.99±3.52 U/0.5 mL), with elevated levels in mild and moderate subgroups as compared with severe periodontitis. Thiol concentrations were comparable in these media, 14.43±1.57 micromol /L in GCF and 15.09±2.26 micromol/L in saliva. Following treatment, superoxide dismutase and thiol antioxidant concentrations significantly improved in all the patient groups. The reduction of the inflammatory response following therapy resulted in improved antioxidant profiles in both the GCF and salivary compartments.

Flexural strength of prosthesis made with dental composite resin materials plays an important role in their survival. The aim of this study was investigating the effect of nanoclay fillers and Poly (methyl methacrylate)-grafted (PMMA-grafted) nanoclay fillers loading on the flexural strength of fiber-reinforced composites (FRCs). Standard FRC bars (2 × 2 × 25 mm) for flexural strength testing were prepared with E-glass fibers and a synthetic resin loaded with different quantities of unmodified nanoclay and PMMA-grafted nanoclay filler particles (0% as control group, 0.2%, 0.5%, 1%, 2%, 5%). Flexural strength and flexural modulus were determined. The data were analyzed using 2-way, 1-way ANOVA and post hoc Tukey’s test (a = 0.05). The fracture surfaces were evaluated by Scanning Electron Microscopy. For groups with the same concentration of nanoparticles, PMMA-grafted filler-loaded group showed significantly higher flexural strength, except for 0.2% wt. For groups that contain PMMA-grafted nanoclay fillers, the 2% wt had the highest flexural strength value with significant difference to other subgroups. 1% wt and 2% wt showed significantly higher values compared to control (P < 0.05). None of the unmodified nanoclay particles loaded group represented statistically higher values of flexural strength compared to control group (P > 0.05). Flexural modulus of 2%, 5% wt PMMA-grafted and 0.5%, 1%, 2%, 5% wt unmodified nanoclay particles-loaded subgroups decreased significantly compared to control group (P < 0.05). PMMA-grafted nanoclay filler loading may enhance the flexural strength of FRCs. Addition of unmodified nanoparticles cannot significantly improve the flexural strength of FRCs. Addition of both unmodified and PMMA-grafted nanoclay particles in some concentrations decreased the flexural modulus.

Nickel-titanium (Ni-Ti) rotary instrument files are important devices in Endodontics in root canal preparation. Ni-Ti file breakage is a critical and problematic issue and irrigation techniques were applied to decrease risk of file failure root. The aim of the present study was to compare the temperature gradient change of different irrigation solutions with Ni-Ti rotary instrument system during root canal preparation and also to define their effects on the file failure. A novel computerized instrumentation was utilized and thirty standard (ProFile #25/.04) files were divided into three groups and subjected to a filing in the root canal test. Changes in temperature on teeth under constant instrumental conditions with custom-designed computerized experimental apparatus were measured by using a temperature sensor bonded to the apical hole. A rotary instrument for canal preparation in three series of solution was used and the changes in temperature after each solution were compared. Finally, the file failure results were mentored according to each step of test. Comparisons were performed between group status clinically by using ANOVA (t) test, once the sample showed up normal and differences of P<0.01 were considered significant. All data collected were computerized and analyzed for frequency, distribution, and statistical description. There was a decrease in the temperature of the instruments, which were immersed in 5% NaOCl, when compared with the water group (P<0.01). There was also a decrease in the temperature of the instruments immersed in water, when compared with the no solution group (P<0.01). Test results showed that sodium hypochlorite, water, or air of root canals does alter the properties of gradual temperature change and contributes to the failure of the instruments. By immersing the file in 5% NaOCl, the temperature gradient decreased and instrument failure was reduced.

Based on contradictory findings concerning the use of lasers for enamel etching, the purpose of this study was to investigate the shear bond strength of teeth prepared for bonding with Er-YAG laser etching and compare them with phosphoric acid etching. In this in vitro study forty – eight premolars, extracted for orthodontic purposes were randomly divided in to three groups. Thirty-two teeth were exposed to laser energy for 25 s: 16 teeth at 100 mj setting and 16 teeth at 150 mj setting. Sixteen teeth were etched with 37% phosphoric acid. The shear bond strength of bonded brackets with the Transbond XT adhesive system was measured with the Zwick testing machine. Descriptive statistics, Kolmogorov–Smirnov test, of homogeneity of variances, one- way analysis of variances and Tukey’s test and Kruskal Wallis were used to analyze the data. The mean shear bond strength of the teeth lased with 150 mj was 12.26 ± 4.76 MPa, which was not significantly different from the group with acid etching (15.26 ± 4.16 MPa). Irradiation with 100 mj resulted in mean bond strengths of 9.05 ± 3.16 MPa, which was significantly different from that of acid etching (P < 0.001). laser etching at 150 and 100 mj was adequate for bond strength but the failure pattern of brackets bonded with laser etching is dominantly at adhesive – enamel interface and is not safe for enamel during debonding.

Early childhood caries (ECC) is a virulent form of dental caries that can destroy the primary dentition of preschool children. The purpose of this study was to investigate a possible association between ECC with serum iron and serum ferritin levels. Following the ethical approval, 204 children aged 24–71 months were recruited for a double-blind, randomized cross-sectional study. Each child was examined clinically for dental caries using the World Health Organization criteria in Rafsanjan, Iran. Decayed, extracted, and filled primary teeth (deft) index was used to measure the dental caries. To determine serum iron and serum ferritin levels 2 mL blood was collected from each child. Data were then analyzed by Pearson’s correlation coefficient and t-test using SPSS-16.0 software. The mean values and their standard deviations of the deft index and levels of serum iron and ferritin were 2.4(± 3.3), 93.8(± 29.0) μg/dL and 63.1(± 32.2) ng/mL, respectively, with the two latter within. There was no significant difference between genders. Pearson’s correlation coefficient showed that there was a statistically significant inverse association between ECC and serum iron level (P<0.05); but no association was found with the serum ferritin level. The deft index decreased significantly with increasing serum iron levels, but there was no association between ECC experience and serum ferritin levels.

The ability of mineral trioxide aggregate (MTA) to strengthen the tooth structure has been studied with contradictory results, and there is a lack of data in the case of Calciumenriched mixture (CEM) cement as a novel endodontic biomaterial. The aim of the present study was to evaluate the reinforcing effect of MTA and CEM cement on simulated immature teeth. This ex vivo study was carried out on a total of 46 human maxillary incisors. Access cavities were prepared. Five teeth were randomly selected as negative control. The root length of the remaining teeth was standardized to 9 mm. Rotary files and peeso reamers were used to enlarge the canals. The prepared specimens were randomly assigned into three experimental (n = 12) and a positive control (n = 5) groups. In groups 1 and 2, the canals were filled with MTA or CEM cement, respectively. In group 3, a 5-mm MTA plug was placed, and the remainder of the canal was filled with composite resin. The canals of the positive control were kept unfilled. After 6 months, the teeth were tested for fracture strength in a universal testing machine. The groups were compared using Univariate analysis of variance (ANOVA). There were significant differences between fracture strength of experimental groups with that of both control groups (P<0.05). However, the differences among the three experimental groups were not statistically significant (P>0.05). After 6 months, MTA and CEM cement exhibit distinct reinforcing effect on immature teeth.

Chlorhexidine (CHX) as a gold standard chemical agent appears to be the most effective antimicrobial agent for reduction of both plaque and gingivitis. The aim of this study was to compare the efficacy of two concentrations of digluconate chlorhexidine (CHX) solutions (0.12% and 0.20%) on gingival indices and the level of dental staining during 14 days. in this double-blind controlled clinical trial study 60 patients with moderate to severe gingivitis aged 17–56 years were randomly selected and divided to three groups: Group I (placebo) Group II (0.12% CHX), and Group III (0.2% CHX). Patients rinsed their mouthwashes twice a day after brushing. Before the examination and after 14 days plaque index, gingival index, bleeding index, and stain index were evaluated. The data were analyzed by “Mann–Whitney” test and P value was 0.05. the results showed that plaque index and gingival index significantly reduced in Groups II and III in comparison with the placebo group (P < 0.0001). However, the two concentrations did not differ significantly from each other (P = 0.552). Same results were observed in term of gingival bleeding index with this different that 0.2% CHX was significantly more efficient than 0.12% CHX (P < 0.0001). CHX mouthrinse, both concentrations, significantly increased the dental staining level (intensity and area) in comparison with the placebo group. Remarkable difference also was seen between 2 CHX concentrations so that the 0.2% CHX caused much more staining on the teeth than 0.12% CHX. based on the results of this study we can conclude that the lower concentrations of CHX should be prescribed, decreasing side effects, since higher concentrations do not seem to be more effective in controlling dental plaque and gingivitis.

Chewing gum is a habit practiced regularly by a relatively high proportion of individuals in many countries including India, and its use has increased within the last decade. The aim of this study was to determine the effects of sugar-free and sugar chewing gums on plaque deposition. The study is a double blind clinical trial involving 16 healthy volunteers (divided into 2 groups) in a 4-day plaque regrowth model. On day one, subjects received professional prophylaxis, suspended oral hygiene measures, and commenced chewing their allocated product. Gum chewing was one piece chewed for 30 minutes 3 times a day. On day 5, subjects were scored for plaque with the help of Silness and Loe Index. Results show sugar-free group have a lesser mean plaque score of 0.98 as compare to sugar group (1.23), though this difference was not statistically significant. The sugar-free gums can be used as an adjunct to mechanical oral hygiene measures.

Reduced time and appropriate bond strength of brackets is one of the most important aspects of orthodontic treatments. Prolonged halogen light curing for bonding of brackets is undesirable, so the purpose of this study was to compare the shear bond strength of brackets bonded with halogen light and plasma arc system.Materials and Mehods: This was an experimental in vitro study. A total of 60 intact premolar teeth were collected and divided into four groups. Stainless steel orthodontic brackets were bonded to them. In groups 1 and 2, curing was done using halogen light given for 20 seconds from two and four angles. In groups 3 and 4, curing was carried out using the plasma arc system for 6 seconds from two and four angles. The shear bond strength was recorded by Instron. The statistics of ANOVA, Tukey’s test, and T-test were used in data analysis. There was a statistically significant difference in shear bond strength among the four groups (P = 0.043) and between group 1 with group 2 (P = 0.035). Yet, there was no statistically significant difference between brackets bonded with plasma arc and those bonded with halogen light or between the two groups of plasma arc. Using the plasma arc system is superior to other methods due to reduced curing time. Also, since in using the halogen light system, an increase in curing periods from different angles resulted in a significant increase in shear bond strength; it is advisable to apply the halogen light from different angles.

Reduced time and appropriate bond strength of brackets is one of the most important aspects of orthodontic treatments. Prolonged halogen light curing for bonding of brackets is undesirable, so the purpose of this study was to compare the shear bond strength of brackets bonded with halogen light and plasma arc system.Materials and Mehods: This was an experimental in vitro study. A total of 60 intact premolar teeth were collected and divided into four groups. Stainless steel orthodontic brackets were bonded to them. In groups 1 and 2, curing was done using halogen light given for 20 seconds from two and four angles. In groups 3 and 4, curing was carried out using the plasma arc system for 6 seconds from two and four angles. The shear bond strength was recorded by Instron. The statistics of ANOVA, Tukey’s test, and T-test were used in data analysis.. There was a statistically significant difference in shear bond strength among the four groups (P = 0.043) and between group 1 with group 2 (P = 0.035). Yet, there was no statistically significant difference between brackets bonded with plasma arc and those bonded with halogen light or between the two groups of plasma arc. Using the plasma arc system is superior to other methods due to reduced curing time. Also, since in using the halogen light system, an increase in curing periods from different angles resulted in a significant increase in shear bond strength; it is advisable to apply the halogen light from different angles.

Malignant transformation of ameloblastomas arising from an odontogenic cyst or de novo is wellrecognized. Malignancies in ameloblastomas may involve metastasis or a local dysplastic change in the tissue. The latter are classified as ameloblastic carcinomas. A 75-year-old male presented with a mandibular cystic swelling, with no evidence of metastasis. Dysplastic ameloblastic cells with spindlecell transformation were seen arising from a cystic lining with features of a unicystic ameloblastoma. Immunohistochemically the lesion stained positive with cytokeratin 8,19 and alpha smooth muscle actin, but was negative for vimentin. A diagnosis of spindle-cell ameloblastic carcinoma was made. Spindle-cell ameloblastic carcinomas are rare and this is the second case arising from a unicystic ameloblastoma reported in literature. The recognition of this transformation and inclusion of this entity in the classification of ameloblastic carcinomas is stressed.

The clinical facts and radiologic findings are very important in the diagnostic evaluation of jaw swellings, and must be considered along with histologic findings. Osteoblastoma, an uncommon primary lesion of the bone that occasionally arises in the jaws, is one such lesion causing a localized jaw swelling. Clinically, osteoblastoma can be symptomatic or even remain symptom-free, and may be diagnosed only on routine radiographic examination. Histologically and clinically, differential diagnosis for osteoblastoma ranges from a variety of benign and malignant tumors that poses a diagnostic dilemma. Stressing the importance of the correct diagnosis of such lesions, this report discusses a case of aggressive osteoblastoma of the mandible posing as a diagnostic dilemma.

Melanoma of the oral cavity is a rare malignant disease. On account of the presence at relatively obscure areas in the oral cavity, most of oral malignant melanomas are diagnosed at a late stage. Early diagnosis is essential for successful treatment and perhaps is the key factor in improving the prognosis of oral malignant melanoma. However, no large clinical series exist, and in fact, clinical cases are the sole key source of information. We hereby present a series of four cases of primary oral malignant melanoma of South-East Asian ethnic origin, with long-term, regular follow up. The age of the patients ranged between 40 and 70 years, with equal sex predilection, and the gingiva was found to be the most common site of its occurrence. Based on clinical and histological parameters, all the cases were diagnosed as primary malignant melanoma, which were further confirmed by using immunohistochemical markers.

Hemangiomatous ameloblastoma (HA), which is a rare ameloblastic variant, is presented in a 15-year-old boy in the maxillary right molar region associated with unerupted canine and premolars. Radiologic and computed tomographic analysis was suggestive of cystic lesion. An histology picture confirmed the diagnosis of HA. There are less than eight cases documented in the literature and mostly are in the middle age with mandibular location. This is first ever reported case of HA in a 15-year-old boy with maxillary location. Due to less number of documented cases and no longterm follow-ups, clinical behavior and prognosis of this lesion are uncertain. In this case report, the clinical, histological, and radiographic features of HA are presented.

Lipoma is a benign mesenchymal tumor of fat with uncertain pathogenesis. Although the most common mesenchymal neoplasm in trunk and proximal portions of the extremities, it is rarely seen in the oral cavity. Oral lipomas are clinically soft, smooth-surfaced nodular masses that mostly are less than 3 cm in size. Typically the tumor is asymptomatic unless bitten or become noticeable because of their size. The buccal mucosa and buccal vestibule are the most common intraoral sites and account for 50% of all cases. Reported here is a relatively large lipoma of buccal mucosa that was treated surgically under local anesthesia. In an 18-month postsurgical follow up no complication or recurrence has occurred. This case will also be compared to intraoral lipomas reported in Iranian population. As lipomas are usually smaller than 3 cm in diameter, lipoma with the size reported, is of clinical importance. Since the large lipomas are in differential diagnosis with other, even malignant, mesenchymal, or salivary gland tumors. Thus, this case report recommends clinical awareness in diagnosis of large intraoral soft tissue lesions.

Primary oral melanoma is a rare neoplasm of melanocytic origin, accounting for 0.5% of all oral malignancies. The “chameleonic” presentation of a mainly asymptomatic condition, rarity of this lesion, poor prognosis, and the necessity of a highly specialized treatment are factors that should be seriously considered by the involved health provider. Here is a case report presenting a malignant melanoma of oral mucosa in 48-year-old male patient on maxillary gingiva. The lesion was removed by partial maxillectomy and patient is disease free after 11 months of regular followup. This case provides an example of how dental clinicians play a major role in the identification of pigmented lesions of oral cavity and also emphasize on the fact that any pigmented lesion detected in the oral cavity may exhibit potential growth and should be submitted to biopsy to exclude malignancy.

This case report describes the multidisciplinary management of subgingival horizontal crown–root fracture of an immature permanent maxillary central incisor in a 10-year-old boy. After removal of the fractured fragment, pulpotomy was performed within 48 h from the injury to promote apexogenesis. The tooth was orthodontically extruded until the fracture line was located above the alveolar bone level. Frenectomy, supracrestal fiberotomy, and crown lengthening were performed after adequate stabilization of the extruded tooth for 5 months. Finally, the tooth was restored with composite resin by using the acid etch technique. This report highlights that a multidisciplinary treatment approach with strict cooperation among specialists to manage a complicated crown–root fracture can save and restore a traumatized immature permanent tooth.