Frontiers in Dentistry
Volume:8 Issue: 2, Spring 2011

Dental caries and periodontal diseases are caused by infection of teeth and supporting tissues due to complex aggregate of bacteria known as biofilm, firstly colonized by streptococci. The main purpose of this in vitro study was to evaluate the antimicrobial effects of toluidine blue O (TBO) and Radachlorin® in combination with a diode laser on the viability of Streptococcus mutans. Bacterial suspensions of Streptococcus mutans were exposed to either 0.1% TBO associated with (20 mW, 633 nm diode laser, continuous mode, 150 s) or 0.1% Radachlorin® and laser irradiation (100 mW, 662 nm diode laser, continuous mode, 120 s). Those in control groups were subjected to laser irradiation alone or TBO/Radachlorin® alone or received neither TBO/Radachlorin® nor laser exposure. The suspensions were then spread over specific agar plates and incubated aerobically at 37°C.Finally, the bactericidal effects were evaluated based on colony formation. Potential bacterial cell killing was only observed following photosensitization with TBO and 3 j/cm2 laser exposure (p<0.05), whereas Radachlorin® showed significant reduction in dark condition compared to laser exposure (p<0.05). TBO-mediated photodynamic therapy seems to be more efficient than Radachlorin ® in significantly reducing the viability of Streptococcus mutans in vitro.

Dental caries is a common infectious disease. Streptococcus mutans is the prevalent decay microorganism. The anti Streptococcus mutans activity of non fermented and semi-fermented tea has been shown. The aim of this study was to determine the anti Streptococcus mutans activity of Iranian green and black tea (non fermented and fermented type). The study was experimental. The aerial parts of wild-growing Camellia sinensis were collected from Lahijan province. The methanolic extract of green and black tea were examined on Streptococcus mutans (ATCC3566). Five different concentrations (50mg/ml, 100mg/ml, 200mg/ml, 300mg/ml and 400 mg/ml) of tea extracts were tested using the well assay method. The agar dilution method recommended by the NCCLS standards (National Committee for Clinical Laboratory Standards) was used. The minimum inhibitory concentration (MIC) was determined as the lowest concentration of extract inhibiting visible growth of the organism on the agar media plate. Minimum bactericidal concentration (MBC) was detected from MIC. The Iranian green and black tea had an antibacterial effect on 100 to 400 mg/ml concentrations. The minimum inhibitory concentration of green and black tea was 150 and 50 mg/ml, respectively. The mean diameter of inhibition zone were 9.5 mm and 10.9 mm for methanolic extract of green and black tea, respectively. Both Iranian non fermented (green tea) and fermented (black tea) have anti Streptococcus mutans activity in vitro. The anti Streptococcus mutans activity of black tea appears on a lower concentration than green tea.

Application of sodium ascorbate as an antioxidant and calcium hydroxide as a buffering agent following intracoronal bleaching has been recommended. The aim of this study was to investigate the effect of using the mentioned materials on shear bond strength of composite resin to the bleached dentin. In this in vitro investigation, sixty human sound premolars were divided randomly into five groups (n=12). Occlusal dentin surfaces were exposed. The negative control (NC) group was not bleached and the other groups were bleached with 35% hydrogen peroxide gel for 5 days. Afterwards, composite cylinders were built up in the positive control (PC) group immediately after bleaching, in the delay bonding (DB) group after one week, in the sodium ascorbate (SA) and calcium hydroxide (CH) groups after 40 hours of treatment with the materials. Then, the samples were stored in 37°C for 24 hours. The specimens were thermocycled (5-55°C, 500 cycles), subjected to shear bond testing by universal machine. The data were analyzed by One-Way ANOVA and Duncan tests (=0.05). There was a significant difference between PC and CH groups in comparison with the other groups (p<0.05), but the difference among other groups was not significant (p>0.05). Application of sodium ascorbate could significantly increase the bond strength of composite resin to bleached dentin, while the use of calcium hydroxide did not affect bond strength.

In all ceramic fixed partial dentures the connector area is a common fracture location. The survival time of three-unit fixed partial dentures may be improved by altering the connector design in regions of maximum tension. The purpose of this study was to determine the effect of buccolingual increase of the connector width on the stress distribution in posterior fixed partial dentures made of IPS Empress 2. To simulate the anatomical condition, we used three-dimensional finite element analysis to generate. Three models of three-unit bridges replacing the first molar were prepared. The buccolingual connector width varied from 3.0 to 5.0 mm. Bridges were vertically loaded with 600 N at one point on the central fossa of the pontic, at 12 points along the cusp-fossa contact (50 N each), or at eight points along the cusp-marginalridge contact (75 N each). Alternatively, a load of 225 N was applied at a 45º angle from the lingual side. Stress concentrations were observed within or near the connectors. The von Mises stress decreased by increasing connector width, regardless of whether the loading was applied vertically or at an angle. Within the limitations of this study, we conclude that increasing the connector width decreases the failure probability when a vertical or angled load is applied

The aim of the present study was to retrospectively evaluate small-diameter (3.3 mm) Straumann® dental implants placed in the maxilla or the mandible over a period of 5 years in function. Twenty- eight partially edentulous patients received a total of 48 implants over a 5-year period. After the standard healing period (3 to 6 months), the implants were restored with single-tooth prostheses or fixed partial dentures. All patients were followed according to a strict maintenance program with regular recalls. The cumulative survival rates of implants were analyzed and prosthetic complications were assessed. After 5 years of function, one single 10-mm-long implant in the maxillary premolar region was lost because of recurrent peri-implant infection in a female patient. Two single 10-mm-long maxillary implants placed in the posterior region were lost due to body fracture. The cumulative 5-year survival rate of the implants was 93.75 %. The most common prosthetic complication was loosening of the occlusal screw. Within the limited observation period and the number of patients included in this study, it may be concluded that the use of small-diameter implants appears to be predictable if clinical guidelines are followed and appropriate prosthetic restorations are provided. However, it should be noted that fatigue fracture may occur.

To report the oral findings, including dental anomalies, ectopic eruption of the maxillarypermanent first molars and periodontal disease and soft tissue alterations, in a subject withApert syndrome. Clinical and radiographic examination of a patient with Apert syndrome,aged 21 years old, not previously submitted for orthodontic or orthognathic treatment.Dental anomalies were present in a patient. Intraoral evaluation revealed poor oral hygienewith varying degrees of periodontal involvement, an arched swelling (pseudo cleft configuration), class III malocclusion, anterior open bite, posterior crossbite, supernumerary teeth, ectopic eruption and creamy white enamel opacities, an excessively large appearing tongue and a v-shaped maxillary arch. The occurrence of typical lateral palatal swellingsagrees with the literature. The high prevalence of dental anomalies and ectopic eruption may suggest a possible etiologic relationship with the syndrome.

Odontogenic keratocysts (OKCs) are one of the most frequent features of nevoid basal cell carcinoma syndrome (NBS). It is linked with mutation in the PTCH gene. Partial expression of the gene may result in occurrence of only multiple recurring OKC. Our patient presented with nine cysts with multiple recurrences over a period of 11 years without any other manifestation of the syndrome.