Frontiers in Dentistry
Volume:6 Issue: 4, Summer 2009

Confocal laser scanning microscopy (CLSM) is relatively a new light microscopical imaging technique with a wide range of applications in biological sciences. primary value of CLSM for the biologist is its ability to provide optical sections from three-dimensional specimen. The present study was designed to assess the thickness content of in vivo accumulated dental plaque using CLSM and scanning electron microscopy (SEM). Acroflat lower arch splints (acrylic appliance) were worn five participants for three days without any disturbance. The formed plaques were assessed using CLSM combined with vital fluorescence technique and SEM. In this study accumulated dental plaque revealed varied plaque microflora vitality and thickness according to participant''s oral hygiene. The thickness of plaque smears ranged from 40.32 to 140.72 µm and 65.00 to 128.88 µm for live (vital) and dead accumulated microorganisms, respectively. Meanwhile, the thickness of plaque on the appliance ranged from 101 µm to 653 µm. CLSM revealed both dead and vital bacteria on the surface of the dental plaque. In addition, SEM revealed layers of various bacterial aggregations in all dental plaques. This study offers a potent non-invasive tool to evaluate and assess the dental plaque biofilm, which is a very important factor in the development of dental caries.

Low-level laser therapy (LLLT) has been increasingly in use over the last few decades in both medicine and dentistry. It has been suggested that LLLT may be helpful in pulpal wound healing following pulp exposure. The purpose of this study was to compare the effectiveness of LLLT and formocresol (FC) application in healing of remaining pulp following pulp amputation in primary molars. A total of 23 contralateral pairs of teeth from 11 children aged 4 to 7 years were selected and matched using clinical and radiographic criteria. One tooth from each pair was randomly assigned to the LLLT pulpotomy and the to FC pulpotomy group. During a 6-month follow-up period, the teeth were examined clinically and radiographically. Eight patients (four in each group) completed six-month and 6 patients (three in each group) completed one-year follow-up. Clinically, no complication was observed in the teeth. However, radiographic assessment revealed signs of periradicular radiolucency in two teeth in LLLT group. Findings of this investigation show that LLLT can be used successfully as a complementary step to pulpotomy procedure in order to help the healing of amputated pulp. Longer follow-up periods are recommended to investigate long-term effect of LLLT pulpotomy on pulp.

Bleaching of the teeth is considered as a safe, effective, and conservative procedure to treat discolored teeth. The aim of the present study was to compare the amount of mercury and silver released from amalgam after applying two brands of carbamide peroxide 16% bleaching gel. For this experimental study, 384 amalgam tablets were prepared. The samples were kept in distilled water for a month and then were randomly classified into three groups (two experimental and one control groups). The experimental groups were placed in two different Carbamid Peroxide 16% gels (Kimia, Iran, and Nite White, USA) and the control group was placed in Phosphate Buffer with pH=6.5. Then the amount of the released mercury and silver ion was determined using AVA-440 analyzer system based on cold-vapor atomic absorption method after 14 and 28 hours. ANOVA and Tukey HSD tests served for statistical analysis. Carbamid proxide 16% gels caused a significant increase in the amount of mercury and silver released from amalgams in experimental groups (P<0.001). The amount of Mercury and silver released from amalgams in Kimia gel was significantly more than Nite White 16% (P<0.001). The mercury release was not time-dependent (P>0.05) but the silver release was (P<0.05). Carbamide peroxide bleaching gels increase mercury and silver release from dental amalgams. The gel brand seems to have a significant influence on the amount of ion released from the dental amalgam.

Noise pollution is one of the most important situations requiring a solution by the contemporary world. The National Institute for Occupational Safety and Health has identified noise as one of the ten leading causes of work-related diseases and injuries. Dentists and dental auxiliaries are exposed to different noise levels while working in dental offices or laboratories. The purpose of this study was to measure the noise level made by different dental instruments in dental offices and laboratories. Measurement of the noise level was performed in 89 dental offices and nine dental laboratories. The noise levels were determined using a sound level meter; type SL-4011 (Lutron), which was placed at the operator''s ear level in dental offices and laboratories and also at two-meter distance from the technician''s ear in laboratories. The maximum sound level was 85.8 dB in dental offices and 92.0 dB in laboratories. In dental clinics, the highest noise was produced by the ultrasonic-scaler (85.8 dB) and the lowest noise (49.7 dB) by the high-volume aspirator, whereas in the laboratory, the highest noise was caused during grinding by the stonecutter (92.0 dB) and the lowest by the denture-polishing unit (41.0 dB). After close evaluation, we believe that the maximum noise level in dental offices, although often beneath the damaging noise level for the human ear, is very close to the limit of hearing loss (85.0 dB). However, laboratory technicians may be at risk if they choose not to wear ear protection (earplugs or earmuffs).

The aim of this in vitro study was to compare the coronal microleakage between Streptococcus sanguis per se and a mixture suspension of E. faecalis and C. albicans in root canals filled with Gutta-percha and either AH 26 or AH Plus sealer. One-hundred and ten extracted human teeth were decoronated to a standardized root length of 14 mm and prepared using Mtwo nickel-titanium (Ni-Ti) instruments to a master apical file size 35, 0.04 taper and obturated with gutta-percha and either AH 26 or AH Plus sealers by lateral condensation. After setting of the sealers, the teeth were randomly divided into two experimental groups (n=50) and two control groups (n=5). The coronal chambers of half the teeth in each experimental group (n=25) were inoculated with 0.5 ml of Brain Heart Infusion agar containing approximately 3×108 of each microorganism in every ml of Candida albicans (ATCC10231) and Enterococcus faecalis (ATCC29212) using a sterile micropipette. The other half of the teeth of each experimental group were inoculated with Streptococcus sanguis (ATCC10556) with the same concentration. The days of microbial penetration were noted for evaluation. The data were statistically analyzed using Kaplan Meier and log-rank tests. There were no statistically significant differences between the four experimental groups regarding the leakage rate (P=0.130). Under the conditions of this study, there was no difference in the microbial penetration of AH 26 and AH Plus sealers at 60 days.

Oral lesions are among the important reasons for seeking dental care. Being frequently encountered, giant cell lesions form an important group of oral lesions. The epidemiologic data on these lesions, however, is scarce in Iran. The present study investigated epidemiological and demographic characteristics of giant cell lesions in oral biopsies done in one of the largest oral pathology departments in Iran. This descriptive survey studied the existing biopsy records of 2265 patients referred to the Department of Oral Pathology in Shahid Beheshti Dental School from 1991 to 2002. Records with final diagnosis of giant cell lesion were identified. Data on type of lesion, distribution of lesions, the involved jaw, and patients'' gender and age was extracted from these records. In total, 144 giant cell lesions were identified. These lesions comprised peripheral giant cell granuloma (59.5%), central giant cell granuloma (36.6%), cherubism (2.5%), and aneurysmal bone cyst (1.4%). Most of the cases had been occurred among women (54.9%), in their second and third decades of life (49.4%). The anterior region of the mandible was the most common location of these lesions (26.2%). In approximately half of the cases, the first clinical diagnosis was similar to the histopathologic diagnosis. The giant cell lesions were more common in women and in the anterior region of the mandible. More commonly, they occurred in the second and third decades of life unilaterally. This study elucidates the epidemiologic data of giant cell lesions in Iran and the results can be helpful for dental scholars in various fields.

Making impression to obtain an accurate working cast needs to use accurate impression materials such as polyether. On the other hand, polyether cannot be used easily in places with undercut such as excessive interproximal spaces and under the pontics of fixed partial dentures as it may be locked in these free spaces. In this article, a method is presented to blockout interproximal spaces in order to minimize distortion and to facilitate impression removal from the mouth.