The use of Er:YAG, Nd:YAG and Ga-Al-As lasers in periapical surgery: a 3-year clinical study

OBJECTIVES

In an attempt to increase the successful rate of endodontic surgical procedures this study proposes the use of an association of three lasers in apicectomy: Er:YAG laser, (wavelength 2.94 microm pulse mode), Nd:YAG laser (wavelength 1.064 microm, pulse mode), and Ga-Al-As laser, (wavelength of 790 nm, continuous wave).

BACKGROUND DATA

Previous studies have shown the low success rate of apicectomy by conventional methods due to the presence of remaining bacteria in the surgical site.

METHODS

The Er:YAG laser was used to perform osteotomy and root resection without vibration, discomfort, less contamination of the surgical site, and no smear-layer on the dentine surface. The Nd:YAG laser irradiation through a fiber performed sealing of the dentinal tubules and bacterial reduction of the cavity bone. In addition, the improvement of healing and better post-operative achieved with the Ga-Al-As laser encourages the use of those lasers in periapical surgeries.

RESULTS

Three years follow-up examination of the clinical case showed radiographically significant decrease of the radiolucent periapical area and no clinical signs and symptoms.

CONCLUSION

The outcome of this clinical case indicates that the use of those lasers could be considered an alternative, suitable, and useful method to perform an apicectomy.

Panacinar emphysema: CT and pathologic findings

OBJECTIVE

To determine the ability to assess the presence and extent of panacinar emphysema with CT, two chest radiologists independently reviewed CT of 10 patients with pathologically proven panacinar emphysema and five normal controls.

MATERIALS AND METHODS

Six of 15 cases had conventional 10 mm collimation CT, eight cases had conventional CT and high-resolution CT (HRCT), and one case had HRCT only. In each of the 15 cases a single CT image was compared with the inflated pathologic specimen cut in the transverse plane at the same level as the CT scan. Comparison was made between visual assessment of the severity of panacinar emphysema on CT and pathologic assessment of severity using the modified Thurlbeck panel score.

RESULTS

The correlation between the assessment of extent of panacinar emphysema on CT and the pathologic grade was r = 0.90, p < 0.01 for conventional CT and r = 0.96, p < 0.01 for HRCT. There was less interobserver variation in the grading of emphysema on HRCT (mean 0.6, SD 3.9) than with conventional CT (mean 3.9, SD 11.0). Conventional CT correctly identified or excluded panacinar emphysema in 10 of 14 cases, whereas HRCT was correct in 6 of 9 cases.

CONCLUSION

We conclude that HRCT allows improved correlation with the pathologic score and decreased interobserver variation than conventional CT in panacinar emphysema. However, emphysema may be missed on both techniques.

Screening for antibodies against infectious bronchitis virus: specificity of the haemagglutination inhibition test

A screening of antibodies against strain M-41 and the Dutch variant strains D-274 and D-1466 of infectious bronchitis virus (IBV) using the haemagglutination inhibition test (HI) was carried out in Chile. The presence of these variant strains has not been reported yet and therefore the probability of finding positive flocks is low. On this basis some statistical analysis were made with those data obtained in order to contribute to the problem of the specificity of the HI test for IBV diagnosis. All sera were distributed in different categories of possible results against each strain according with the HI titre obtained and employing different discrimination levels for a positive or negative status against IBV. It was concluded that discrimination levels varying from 4.0 to 5.0 log2 are useful for establishing the presence or absence of antibodies against IBV but if a serotype specific diagnosis is needed, then the discrimination level should be elevated, specially when secondary immune responses are measured.

Relation between the amount of smooth muscle of venous tissue and the degree of supersensitivity to isoprenaline caused by inhibition of catechol-O-methyl transferase

The relation between the smooth muscle cell mass of dog saphenous vein strips and the degree of supersensitivity to isoprenaline caused by U-0521 (3,4-dihydroxy-2-methyl propiophenone), an inhibitor of the catechol-O-methyl transferase (COMT), was studied. For the quantitative determination of smooth muscle mass, the thickness of the muscle layer as determined by light microscopy and the maximal shortening induced by supramaximal concentration of phenylephrine were used. After the strips had been contracted by 3x10-6M phenylephrine, a concentration which was able to produce an about 90% maximal contraction, dose-response curves to the relaxant effect of isoprenaline were determined in the absence and in the presence of U-0521 (10-4M). It was observed that U-0521 caused marked supersensitivity to the relaxant effect of isoprenaline (varying between 3 and 81 times), as well as an increase of the maximal relaxation caused by this amine (varying between 7 and 120%). The correlation between these data and the smooth muscle cell mass shows that there was a direct proportionality between these parameters. Oxytetracycline (10-4M), an inhibitor of binding of catecholamines to collagen, did not produce any enhancement of the effects of isoprenaline. It is concluded that COMT is related to smooth muscle cells in this tissue.