Frontiers in Dentistry
Volume:2 Issue: 4, Autumn 2005

Statement of Problem: Reconstruction methods are an essential prerequisite for functional rehabilitation of the stomatognathic system. Platelet-rich plasma (PRP) offers a new and potentially useful adjunct to bone substitute materials (e.g. Xenografts) in oral and maxillofacial bone and implant reconstructive surgery. An animal study was carried out to investigate the influence of PRP on the regeneration of non-critical sized bony defects, treated with Deproteinized Bovine Bone Mineral (DBBM). Eight New Zealand white rabbits were included in this randomized, pilot study. Three equal cranial bone defects (36 mm) were created and immediately grafted with DBBM and PRP+DBBM; one of them was left unfilled to serve as a control. The defects were evaluated using histologic and histomorphometric analysis at 2, 4, 8 and 12 weeks. The histomorphometric findings showed a significant increase in bone area and trabecular maturity in experimental defects as compared to the control at 4, 8 and 12 week intervals. A significant increase in bone formation was seen with the addition of PRP to DBBM at 2, 4 and 8 week intervals. At 12 weeks, the level of bone formation was similar between the two groups. There was also a significant increase in the rate of biodegradation of the DBBM particles with the addition of PRP at 2, 4, 8 and 12 weeks. No foreign body reaction and severe inflammation was seen in any of specimens. Within the limitations of this pilot study, it was concluded that the addition of PRP to Xenogenic bone substitute material in non-critical-sized defects of the rabbit cranium showed a histomorphometric increase in bone formation (until the 8th week of healing) and a greater amount of biomaterial degradation throughout the study period.

Statement of Problem: Despite the wide range of new dental materials, there is still a need for biomaterials demonstrating high biocompatibility, antimicrobial effects and ideal mechanical properties. The aim of this study was to histologically evaluate the pulpal response to a conventional glass ionomer, a resin modified glass ionomer and a calcium hydroxide in human teeth. Fifty five deep class V cavities were prepared in premolars of 31 patients and were divided into 3 groups based on application of the following liners: resin modified glass ionomer (Vivaglass Liner), conventional glass ionomer (Chembond Superior) and calcium hydroxide (Dycal). After applying varnish, teeth were filled with amalgam. Each group was further divided into three subgroups according to time intervals of 7, 30 and 60 days. Teeth were then extracted and their crowns were fixed in formalin. Each sample was assessed microscopically for odontoblastic changes, inflammatory cell infiltration, reactionary dentin formation, remaining dentinal thickness and presence of microorganisms. Statistical analysis including Kruskal Wallis and Mann Whitney was carried out for comparison of mean ranks. (P=0.05). In the Vivaglass Liner group, pulpal response was significantly higher on day 7 as compared to days 30 and 60 (P<0.05). Reactionary dentin production was significantly lower after 7 days than after 60 days for all materials (P<0.05). There was no statistically significant difference in pulpal responses among the three groups during the same time intervals (P>0.05). There was no correlation between pulpal responses with micro-organisms and remaining dentin thickness (P>0.05). According to the results of this study, light-cured glass ionomer as well as the other tested lining materials were determined to be biologically compatible with vital pulps in deep cavities of sound human teeth.

Statement of Problem: Variation in paranasal sinus anatomy as shown on computed tomographic scans is of potential significance for it may pose risks during surgery or predispose to certain pathologic conditions. The aim of this study was to assess the relative frequency and concurrence of variations in paranasal sinus anatomy in a given population and to compare the results with previous investigations conducted on different populations. All patients over 16 years of age referred to Valiasr hospital, Tehran, Iran, with paranasal sinus tomographic scans and a clinical diagnosis of chronic sinusitis were considered for this study. After excluding those with altered anatomy (iatrogenic or pathologic), scans of unaltered patients were meticulously analyzed for variations in sinus anatomy. Findings were recorded on the patient’s data sheet. The distance between the maxillary sinus floor and the alveolar ridge at the level of the 1st molar was recorded. All findings were analyzed, and tested with Chi square, where applicable. Overall 143 patients were analyzed (48.3% male and 51.7% female). The frequency of major sinus variations was: Agger nasi cell in 56.7%, Haller cell in 3.5%, Onodi cell in 7%, nasal septal deviation in 63%, Concha bullosa in 35%, and dental anomalies in 4.9% of the studied cases. The distance between the upper alveolar ridge and maxillary sinus floor was 0-30mm (mean 12.16) on the right, and 0-52mm (mean 12.20) on the left. The frequency of anatomic variations in sinus anatomy may be related to race and heredity. A lower number of cases in addition to the use of low yield imaging may explain the discrepancies observed between our results and other investigations. The findings of the present study were based on computed tomography.

Statement of Problem: Recurrent aphthous stomatitis (RAS) is one of the most common diseases affecting the oral mucosa. Many topical and systemic medications used to treat RAS have adverse local and systemic effects. Chamomill (kamillosan) has been shown to be an effective drug, without any noticeable side effects. The aim of present study was to assess the efficacy of a chamomill mouthrinse on RAS in comparison with a placebo mouthrinse. The study was designed as a double blind randomized placebo controlled clinical trial with participation of 50 patients diagnosed with RAS. They were randomly divided into two groups: 26 patients forming the test group, received chamomill mouthrinse and 24 patients constituting the control group received a placebo rinse. All subjects were instructed to use the solutions three times a day until complete resolution of the lesions. Treatment outcome was assessed on days 3 and 5 and at the exact healing time. The ability of the solution to control the pain and burning sensation and the diameter of the ulcers was evaluated. Statistical analysis was performed using the 2 and unpaired t test for comparison between the two groups. The chamomill group showed a significant reduction in the time required for controlling the pain and burning sensation (P<0.01). Ulcer diameter and healing time were also decreased (P<0.01). Chamomill mouthrinse was effective in the treatment of RAS without producing adverse effect.

Statement of Problem: Burning mouth syndrome (BMS) is characterized by a burning sensation in the tongue or other oral sites, usually in the absence of clinical and laboratory findings. The aim of this study was to evaluate the main epidemiological and clinical features involved in burning mouth syndrome in Zahedan; southeast of Iran. In this case series study, 89 BMS patients were selected from those referred to the Department of the Oral Medicine, Faculty of Dentistry, and Khatam-ol-anbia, central hospital, Zahedan University of Medical Sciences, during 2002 to 2003. The study group consisted of 62 female (69.7%) and 27 male (30.3 %) patients, with a mean age of 60.9 years, ranging from 40 to 89 years. In all cases a study protocol, specially designed for this disease was completed, including general, medical and oral information and an intraoral examination. Comparative and descriptive statistical analysis was performed. The Chi-square test was considered significant at p< 0.05. The 50-59 years age group showed the highest prevalence among the studied cases (24.3%). The tongue was the most frequent location of symptoms, affected in 86 patients (96.6%). In addition to the burning sensation, 25.8% and 48.3% of the patients complained of oral dryness and dysgusia, respectively. Type III BMS was the most common subtype (50.6%). In women, 90.3% were postmenopausal. Type II diabetes was observed in 36% of the patients and 37.1% suffered from respiratory disease, 23.6% from gastritis, 15.7% from liver diseases, 30.3% from renal disease, 40.4% from hypertension and 43.8% had sleep disorders. Also, 52.8% revealed seasonal allergy, 32.6% had temporomandibular joint disorders and 59.6% had poor oral hygiene. BMS is a complex and multifactorial disease process in which numerous possible etiologies must be eliminated before the proper treatment can be initiated.

Statement of Problem: The connector area is the weakest zone of an all-ceramic fixed partial denture (FPD), where most catastrophic failures of the prostheses tend to occur. The aim of the present study was to assess the effect of the convergence angle of abutments on the fracture resistance of three-unit fixed partial dentures made of IPS-Empress2. Forty extracted human premolars and molars were used to reproduce twenty, 3-unit fixed partial dentures, for the replacement of second premolars. All teeth were prepared according to the guidelines outlined for all-ceramic crowns and bridges, except for the convergence angles of the abutments. The specimens were randomly divided into two groups of 10, with total occlusal convergence angles of 12° and 22°. Fixed partial dentures with a uniform thickness of 0.8 mm were fabricated using IPS-Empress2 and were bonded to the corresponding models. Connector dimensions were set to 4 mm height and 4mm width. The radius of curvature at the gingival embrasure was carved to 0.9 mm. All specimens were exposed to 10,000 pre-loading cycles and a load of 40 N at a frequency of 1.3 Hz in a standardized testing machine at a cross head speed of 1mm/min. Student t-test was performed to detect any difference in the mean fracture resistance between the two groups (α = 0.05). Mean failure loads (and standard deviations) of the 12° and 22° groups were 1009.12 N (208.05) and 1182.72 N (144.67), respectively. Statistical analysis revealed a significant difference (P <0.04) between the mean failure loads of the two groups. Most fractures occurred through the connectors. The mean failure loads of the investigated fixed partial dentures were higher in the abutments with 22° taper as compared to those with a taper of 12°.

Statement of Problem: Element release from dental casting alloys into the oral environment is of clinical concern and is considered to be a potential health problem to all patients. The aim of this study was to investigate the metallic ion release of four base metal alloys. Two Ni-Cr (Minalux and Supercast) and two Co-Cr alloys (Minalia and Wironit) were examined. Nine specimens of each type were prepared in 13×11×1. 4 mm dimensions and each of the four alloys (3 specimens per group) were conditioned in artificial saliva at 37ْ c for one, three and seven days. The conditioning media were analyzed for element-release using Inductive Coupled Plasma Atomic Emission Spectrophotometer (ICPAES). Collected data were statistically analyzed using ANOVA and Duncan multiple range test (P< 0. 05). The greatest amount of element release was seen after seven days (134. 9 ppb Supercast, 159. 2 ppb Minalux, 197. 2 ppb Minalia, and 230. 2 ppb Wironit). There was a significant difference between the released elements from the alloys after the three conditioning times (p<0. 001). Element release from the studied alloys is proportional to the conditioning time. The Ni-Cr alloys tested in this investigation were more resistant to corrosion as compared to the Co-Cr alloys in artificial saliva. Supercast had the highest corrosion resistance.

Statement of Problem: Streptococcus viridans is one of the most important micro-organisms in the establishment of infections leading to dental caries and heart valve damages. Therefore the diagnosis and prevention of these infections is critical in health care. The aim of this in-vivo study was to determine the prevalence of viridans streptococci in abscesses occurring in the maxillofacial region. The study sample consisted of 39 patients with maxillofacial abscesses, referred to the Department of Oral Surgery Faculty of Dentistry Tehran University of Medical Sciences and Dr. Shariati Hospital, Tehran University of Medical Sciences. Extra-oral incision, drainage and pus collection followed by culture, staining and biochemical and sugar fermentation tests were carried out for all participants. In the present study %53.84 and 46.16% of the patients had negative and positive culture results, respectively. In the positive culture group, %2.5 of the viridans streptococci were streptococcus salivarius, %4.6 streptococcus sanguis and %17.9 were streptococcus mutans. The findings of this study showed that viridans streptococci are an important factor in the development of metastatic and maxillofacial infections which can pose a significant threat to the patient’s life.