Dental trauma that require fixation in a children's hospital.

Children and adolescents who suffer traumatic injuries often seek emergency treatment at a Children's Hospital. Complex injuries to permanent teeth and their periodontium require immediate repositioning and stabilization. Many of these emergencies are treated by pediatric dental residents at the Women and Children's Hospital of Buffalo, Buffalo, New York. The purpose of this study was to characterize these complex injuries of permanent teeth that require emergency treatment in a Children's Hospital. All of the cases of dental trauma which had involved permanent teeth and which had been treated with a splint in 2001 and 2002 were reviewed. There were 79 patients that were between 5 and 19 years of age with twice as many males (54) as females (25). The number of males increased from childhood (5-10 years) to early adolescence (11-15 years) and then decreased rapidly in late adolescence (16-19 years), whereas the number of females decreased steadily with age. Most of the incidents occurred during the summer months (72%), particularly in June and July (42%), and Fridays and Saturdays were the busiest days of the week. Most of the injuries were caused by organized and recreational sporting activities (39%) and accidental falls (33%), followed by interpersonal violence (15%) and a few motor vehicle accidents (7%). The 173 permanent tooth injuries were mostly luxations (62%) or avulsions (20%), with only a few fractures of the alveolar bone (5%) or tooth root (1%). Most of the displacements were lateral luxations (40%) or extrusions (18%) with only a few intrusions (3%). These injuries most commonly afflicted the maxillary central incisors (54%), followed by the maxillary laterals (18%) and mandibular centrals (17%). The emergency treatment that was provided at the Children's Hospital included replantation and repositioning, and the placement of a semi-rigid or flexible splint.     

Quantitative three-dimensional analysis of root canal curvature in maxillary first molars using micro-computed tomography

In endodontic therapy, access and instrumentation are strongly affected by root canal curvature. However, the few studies that have actually measured curvature are mostly from two-dimensional radiographs. The purpose of this study was to measure the three-dimensional (3D) canal curvature in maxillary first molars using micro-computed tomography (microCT) and mathematical modeling. Extracted maxillary first molars (46) were scanned by microCT (502 image slices/tooth, 1024 X 1024 pixels, voxel size of 19.5 x 19.5 x 39.0 microm) and their canals reconstructed by 3D modeling software. The intersection of major and minor axes in the canal space of each image slice were connected to create an imaginary central axis for each canal. The radius of curvature of the tangential circle was measured and inverted as a measure of curvature using custom-made mathematical modeling software. Root canal curvature was greatest in the apical third and least in the middle third for all canals. The greatest curvatures were in the mesiobuccal (MB) canal (0.76 +/- 0.48 mm(-1)) with abrupt curves, and the least curvatures were in the palatal (P) canal (0.38 +/- 0.34 mm(-1)) with a gradual curve. This study has measured the 3D curvature of root canals in maxillary first molars and reinforced the value of microCT with mathematical modeling.     

pH regulation of urease levels in Streptococcus salivarius

Potential mechanisms for regulation of urease levels in Streptococcus salivarius were examined, including: induction by urea, nitrogen or carbon source repression, and effects of pH and CO2 (because CO2 enrichment enhanced urease detection on urea agar plates). Regulation by either pH or CO2 was confirmed by comparison of the urease accumulation pattern during anaerobic growth under CO2 with that under N2. Under CO2, there was an initial buffering plateau at pH 6.2 and a rate of Streptococcus salivarius urease accumulation three-fold that under N2, with a pH 7.6 plateau. With both gas phases there was also an increase in the rate of urease appearance coincident with the decrease in medium pH following the pH plateau. The effects of pH, CO2, and HCO3- on urease levels and on growth were separately assessed by culture in media containing 0, 25, 100 mmol/L KHCO3 buffered at different pH levels. There was an inverse relationship between the logarithm of the urease level after 24-hour growth and the pH during growth-the urease specific activity was 100-fold higher at pH 5.5, compared with pH 7.0 and above. HCO3-/CO2 (100 mmol/L) had little effect on urease levels, but was essential for growth at pH 5.5. There was no significant urease induction by urea, or repression by ammonia or glucose. There was also evidence of pH regulation of urease levels in some staphylococci, Klebsiella pneumonia, and Corynebacterium renale, but not in Actinomyces naeslundii and several other species. We conclude that the external pH is a major factor regulating urease levels in S. salivarius and possibly some other species-a mechanism equivalent to urease repression by OH-.     

The bacteria responsible for ureolysis in artificial dental plaque

The origin of ureolytic activity in artificial-mouth plaques was established by assessing the contribution to plaque ureolytic activity of the isolated bacteria. To overcome losses of ureolytic activity caused by the unstable presence of urease in oral bacteria, ureolytic bacteria were isolated from an exceptionally active plaque (1 mumol NH3/min per mg protein) in which 63 per cent of the flora was ureolytic. After their ability to metabolize urea was stabilized, 13 ureolytic bacteria remained: seven strains of Streptococcus salivarius, one Streptococcus bovis, two Staphylococcus epidermidis and three Staphylococcus haemolyticus. Their urease activity, measured after growth into stationary phase, was reproducible and strain specific with a 20-fold range within each genus. The mean ureolytic activity of each species, when weighted by its calculated incidence in the original plaque, accounted for 40 per cent of the total plaque ureolytic activity. However, these values for urease levels were only a small fraction of the bacterial ureolytic potential. Urease per mg cell protein measured during the growth cycle of a selected Strep. salivarius, and Staph. epidermidis, varied 10-fold, and reached much higher activities (i.e. 6-8 mumol NH3/min per mg of cell protein) than under the growth conditions that were used to assess the contribution of these species to total plaque ureolysis. Thus urea metabolism in artificial plaque was due mainly to Strep. salivarius, with a small contribution from Staph. epidermidis. The presence of further unidentified species of ureolytic oral bacteria need not be invoked.     

Antifungal Effects of Synthetic Human Beta-defensin-3-C15 Peptide on Candida albicans–infected Root Dentin

Introduction

The aim of this study was to assess the antifungal efficacy of a synthetic human beta-defensin-3-C15 peptide (HBD3-C15) in Candida albicans–infected human root dentin.

Trends in oral piercing in Buffalo, New York, high schools

The purpose of this research was to examine the trend of high school adolescents obtaining an oral piercing. A questionnaire was sent to five high schools in Buffalo, NY. Of the 508 questionnaires returned, 49 of the respondents (10%) had an oral piercing. Post-piercing occurrences included swelling, tenderness, numbness, loss of taste, bleeding and pus. Oral piercing maintenance was minimal or non-existent. Dental trauma/piercing-related injuries were common. Researchers concluded that the oral piercing trend in Buffalo, NY, high schools is small; however, students who are getting oral piercings are doing so without parental consent and often show signs of infection.     

Human alveolar bone cells interact with ProRoot and tooth-colored MTA

The cellular response to mineral trioxide aggregate (MTA) is important for the repair and regeneration of periradicular tissues. The purpose of this study was to analyze the response of human alveolar bone cells to MTA. A human alveolar bone chip was obtained from an oral surgical procedure and explant cultures harvested after 3 to 4 weeks of outgrowth in alpha-minimum essential medium supplemented with fetal calf serum. Cells in early passage were seeded onto preset ProRoot (gray) MTA, tooth-colored (white) MTA, and MTA prepared with local anesthetic solution. Scanning electron microscopy showed cells were attached and spread out onto MTA within 24 hours, and proliferated to form a matrix-like layer within 7 days. Cell attachment and cell-surface interactions with the gray and white MTA, and with the MTA prepared with local anesthetic were comparably propagated for 14 days. The surgically derived human alveolar bone cells provided a clinically relevant model that demonstrated the capacity of both ProRoot and tooth-colored MTA to support cell attachment, proliferation, and matrix formation.