Bacterial and fungal microleakage of AH26 and AH Plus root canal sealers.

AIM: To evaluate the penetration of Candida albicans alone and a combination of bacteria through root canals filled with gutta-percha and one or other root canal sealers, AH26 and AH Plus. METHODOLOGY: Eighty teeth were randomly divided into two groups of 40 teeth each and obturated with gutta-percha using either AH26 or AH Plus sealer. A further 10 teeth served as negative controls and 10 as positive controls. The external surface of each root, except the apical 2 mm, was covered with two layers of nail varnish. The teeth were inserted into Eppendorf plastic tubes and suspended in glass bottles containing sterile Schaedler broth. Streptococcus mutans, Streptococcus mitis, Prevotella melaninogenica and Lactobacillus acidophilus were placed in the access cavities of 20 teeth filled with AH26 and 20 with AH Plus. Candida albicans was placed in the access cavities of the other teeth. The culture medium with microorganisms was changed every 7 days. Every 72 h bacterial or fungal growth in the broth was tested up to a period of 90 days. RESULTS: Leakage in the experimental teeth occurred between 14 and 87 days. Leakage was present in 47% of all samples. From the samples with AH26, 45% leaked bacteria and 60% leaked fungi; whilst from the samples with AH Plus, 50% leaked bacteria and 55% fungi. There was no statistically significant difference in penetration of bacteria and fungi between the sealers. CONCLUSION: In this in vitro study, gutta-percha and the sealers AH26 and AH Plus allowed leakage of bacteria and fungi.

Dynamic effects of food consistency on chewing motions.

The purpose of the study was to find evidence of how different types of food consistency affect chewing motions, especially the forward, downward and sidewise extents of motion of the lower jaw. Nineteen individuals with intact tooth sequence, aged from 20 to 37 years, were asked to chew three types of food of different consistency (banana, bread, carrot). The motions of the lower jaw were recorded by ELITE system, i.e. the measurement instrument that by stereo-photo-grametric procedures calculates space co-ordinates of markers on faces of the study subjects. The system enables continuous recording of lower jaw motions in three dimensions, without any possibility of the study subjects' influencing the operation of the instrument, which significantly decreases the possibility of error. Study results have shown that in all 19 subjects a greater food consistency increases the extent of chewing motion. In each individual study subject different average values were found for equal shifts of lower jaw when chewing the same type of food. Although varying from subject to subject, the chewing cycle depends to a great extent on food consistency. By increasing the consistency of a bite, the extent of lower jaw motion has increased in every single study subject.

Dental amalgam mercury exposure in rats.

The aim of this study was to measure the distribution of mercury, in tissues of rats exposed to amalgam over a two months period. Possible interaction of mercury with copper and zinc in organs was also evaluated. Rats were either exposed to mercury from 4 dental amalgams, or fed the diet containing powdered amalgam during two months. Mercury was measured in the kidney, liver and brain, copper in kidney and brain and zinc in kidney. The results showed significantly higher concentrations of mercury in the kidneys and the brains of rats in both exposed groups compared to control. Even after two months of exposure to mercury brain mercury concentration in rats with amalgam fillings was 8 times higher than in the control and 2 times higher than in rats exposed to amalgam supplemented diet. The highest mercury concentration in the latter group was found in the kidneys and it was 5 times higher than in the control group. We found no significant differences between mercury levels in exposed and control rat's liver. Exposure to mercury from dental amalgams did not alter the concentrations of copper and zinc in the tissues. Histopathological analyses of rats tissues did not show any pathological changes. These results support previously proposed nose-brain transport of mercury released from dental amalgam fillings.

Infective endocarditis caused by Veillonella of dental origin.

The purpose of this investigation was to examine whether Veillonella could cause transitory bacteriemia and endocarditis in both pure and mixed cultures when the port of entrance for infection was made in rats' incisors. Incisors of 54 male Zgr: whistar conventional rats were inoculated with pure culture of Veillonella (18 animals) and with mixed culture of S. mutans and Veillonella (18 animals). Remaining 18 incisors (the control group) were treated with saline solution. The animals were sacrificed after 7, 21 and 52 days respectively. Two positive hemocultures were obtained in mixed infection after 21 days of experimental procedure. Histopatological analysis of endocardial tissue revealed changes in 7 (12.96%) cases. Occurrence of acute endocarditis (one case) and chronical (four cases) ones depended on duration of mixed infections. For chronical endocarditis that appears in two animals with pure Veillonela culture we are at a loss of explanation. In conclusion, on the rats model Veillonella can penetrate into circulation in association with S. mutans via the pulp tissue and could be involved in infective endocarditis.

Morphometrical analysis of main and accessory canals in apical root portion of frontal teeth.

Reviewing radiographs may often lead to a wrong conclusion regarding root canal ending (apical constriction) and anatomical apex of the tooth root. Anthropological measurements may help clinicians to understand better root canal ending aberrations in a sense to decide whether to do a revision of the root canal filling or not. The object of this investigation was to examine the deviation frequency, the distance of the major apical foramen from the anatomical apex and occurrence and number of accessory canals in the apical third of the frontal teeth roots. A total of 156 randomly chosen upper and lower permanent incisors and canines, after extraction due to periodontal disease were prepared for the investigation. The access cavity was prepared and root canal therapy was initiated just to prepare endodontic space for methylene blue dye injection. Methylene blue clearly dyed all root canal exits and after that the teeth were cut and examined with a stereomicroscope and a sliding scale. Results indicate that deviation frequency was found in 60.25% of the cases and the mean distance between deviated major foramen and the anatomical root apex was 0.35 mm. Accessory canals were found in 33.33% of the cases in the apex third of the root. Data were statistically elaborated with the method of Chi-square test.

Occupational tooth-wear in clothing industry workers.

A research on tooth-wear was done in a clothing factory, focusing on the teeth of the inter-canine sector in 59 workers who had volunteered for the research. The subjects were in the habit of cutting the thread with their teeth instead of using scissors as was prescribed in the production process. In 53 (89.83%) of the subjects, damages of the incisal portion of the tooth were found, whereas in the remaining 6 (10.17%) there were no such changes. No significant difference could be established in the incidence of tooth-wear between the women workers who cut the thread with their teeth constantly and those who only did that occasionally (p > 0.05). Because of the action of pulling a thread across the incisal edge of the incisor, defects--in the form of solitary, oval or multiple cuts (attributed the values 1, 2 and 3)--had been inflicted on the incisal portion of the teeth. Most frequently those were the defects of the enamel (type 2, 1), but in some cases dentin (type 3), also was affected. A somewhat more severe degree of damage was observed from workers biting the purely polyester-made thread (p < 0.05) than from biting the regular sewing type of thread. Education of the workers seems to be the only useful prevention, since we are dealing with only a bad habit. Therefore, the workers should be warned that the seemingly innocent cutting of thread with their teeth could lead to esthetic, functional and restorative problems.