Oral colonization by Lactobacillus reuteri ATCC 55730 after exposure to probiotics

Objective.  The aim of this study was to investigate whether Lactobacillus reuteri ATCC 55730 can be detected in the oral cavity after discontinuation of administration of a product prepared with this bacterium.
Materials and Methods.  The study consisted of three 2-week periods: clearance period, intervention period, and post-treatment period. Twenty-five volunteers consumed a chewable tablet of L. reuteri ATCC 55730 (10⁸ cfu/tablet) during a 14-day trial period. Saliva samples were collected and cultured onto MRS agar after a clearance period of 2 weeks and then daily after a 2-week intervention period for as long as L. reuteri was found. Lactobacillus reuteri colonies were analysed in saliva samples. The analysis was performed using selective media for L. reuteri followed by confirmation using the specific detection of reuterin produced by L. reuteri.
Results.  The number of L. reuteri carriers decreased gradually, and after 1 week only 8% of the subjects harboured the bacterium. After 5 weeks, L. reuteri was not detected in any of the subjects.
Conclusion.  Consuming L. reuteri for 2 weeks does not seem to be sufficient for permanent colonization of L. reuteri in the oral cavity.     

The prevalence of molar incisor hypomineralization (MIH) in a group of children in a highly polluted urban region and a windfarm-green energy island

Backround.  Children's developing teeth may be sensitive to environmental pollutants such as polychlorinated dibenzo- p -dioxins (PCDDs) and polychlorinated dibenzofurans. The term molar incisor hypomineralization (MIH) was introduced to describe the clinical appearance of enamel hypomineralization of systemic origin affecting one or more permanent first molars (PFMs) that are associated frequently with affected incisors.
Aim.  The aim of this study was to determine the prevalance of MIH in children from the most industrialized and polluted region and the most green-energy island of Turkey.
Design.  In September 2007, a retrospective study was initiated in two elementary schools: one, a group of children ( N  = 153) who fitted the criteria from Tavsancil, Kocaeli ( N  = 109) and the other from Bozcaada island, Canakkale ( N  = 44). The soil samples were collected from selected regions in order to determine the contamination levels in a heavily industrialized area and a non-industrialized area.
Results.  Prevalance of MIH in children in Bozcaada island was 9.1%, while prevalance of MIH was 9.2% in Tavsancil. The PCDD/F levels in soil samples collected from Bozcaada and Tavsancil were determined as 1,12 and 8,4 I-TEQ ng/kg dry soil, respectively ( P  < 0.001).
Conclusions.  In this preliminary study with a small study population, prevalence of MIH did not seem to be associated with the levels of PCDD/Fs in the environment.     

Analysis of forces developed during root canal preparation with the balanced force technique

The aim of this study was to examine the forces and torque developed during root canal preparation with the balanced force technique using a recently described force-analyser device. A tooth was placed in a holder within the Endograph and forces and torques exerted were recorded. These parameters, which can be studied during preparation (on-line) or stored and examinated subsequently (off-line) generated endograms, which showed the forces generated with time. In addition, the endograms of preparations performed by students and endodontists, as well as deliberately induced failures in preparation technique (broken instruments), were compared. The values for the forces and torques depended on the size of the instruments and were related to the phase of the preparation. For the endodontists, the vertical and horizontal forces varied, respectively, from 0.08 ± 0.01 kg for a size 15 to 0.65 ± 0.10 kg for a size 45, and from 0.01 ± 0.005 kg for a size 15 to 0.4 ± 0.1 kg for a size 40. The torque varied from 0.08 ± 1 kg mm⁻¹ for a size 15 to 1.6 ± 0.4 kg mm⁻¹ for a size 45. With the Endograms used as a reference, the relation between the developed vertical forces and the torque became more similar between the groups of endodontists and students. The Endograph provides a new approach to the analysis of preparation technique because it depicts the relationships between the different parameters of the preparation.     

Long-term controlled delivery of levonorgestrel in rats by means of small biodegradable cylinders

Hormone release rates from biodegradable cylindrical implants consisting of a physical matrix of [¹⁴ C]levonorgestrel and copolymers of [³ H]lactic and glycolic acids have been monitored in rats. Two copolymers were evaluated: one consisted of 90 parts L-lactide/10 parts glycolide (90L/10G) containing 33 or 50% hormone by weight, and the other of 50 parts DL-lactide/50 parts L-lactide (50DL/50L) containing 50% hormone. For each system, 4–6 rods (0·8 times 16 mm) providing 19 mg of steroid per rat were subcutaneously implanted into the scapular regions of 5 rats, and ¹⁴ C and ³ H in faeces and urine were determined weekly for 90–724 days. An initial burst of hormone release, peaking at approximately 90 μg day^?1, occurred in the first two weeks. This was followed by an approximately zeroorder release for ¹⁴ C from all systems. Longer-term release rates were approximately 10–30 μg day^?1 for the 90L/10G system containing 33% hormone, a more uniform rate of approximately 25 μg day^?1 for the 50DL/50L system and the highest rate of approximately 40 μg day^?1 for the 90L/10G system containing 50% hormone. ³ H and ¹⁴ C in residual implants of 90L/10G with 33% hormone removed from animals dying of natural causes during the test were assayed. For this system ³ H activity decreased by over 50% within 250 days, compared with < 25 % loss in ¹⁴ C activity. The amounts of ³ H and ¹⁴ C released were similar over much of the subsequent test period. At the end of the test both polymer and drug were essentially depleted. All animals with the 50DL/50L system died late in the test period. Between days 609 and 724 from 13·7-27·2% initial ¹⁴ C and from 10·0-22·1 % initial ³ H was measured in recovered rods. Microscopic inspection of recovered rods showed a loss of core material and tissue encapsulation. There were no signs of local tissue irritation or systemic toxicity.