* Effect of Nd: YAG laser on the apical seal after root-end resection and MTA retrofill: a bacterial leakage study.
- Laser irradiation has been investigated in terms of preventing leakage in retrofilled root canals. The aim of the present study was to evaluate the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser on the bacterial leakage of mineral trioxide aggregate (MTA)-retrofilled roots. In this ex vivo experimental study, 90 single-rooted incisor teeth were filled with gutta-percha and AH26 sealer. The apical 3 mm of all the roots were resected and 3-mm retrocavities were prepared by an ultrasonic device. The specimens were randomly divided into two experimental (n = 25), one positive control (n = 10), and two negative control (n = 10) groups. In the laser + MTA group, the cavity walls were irradiated by Nd: YAG laser prior to MTA placement. In the MTA group, MTA was placed without laser irradiation. The root surfaces were covered with two layers of nail varnish except for the apical 2 mm. The specimens were then embedded in a bacterial leakage test system and examined daily for 90 days. Contamination periods were recorded. Data were analyzed by Kaplan-Meier and Mann-Whitney U tests (α = 0.05). Five teeth with and five teeth without laser irradiation underwent scanning electron microscopic evaluation. The specimens in the laser + MTA group were contaminated earlier than those in the MTA group (p < 0.05). Comparison of survival times between the two groups showed significant differences (p < 0.05). Nd: YAG laser irradiation can decrease the sealing capacity of MTA in comparison to the apical seal achieved by MTA without laser irradiation. Further studies are recommended to provide a better seal for the MTA-retrofilled teeth after laser irradiation.
Overview of noun study
The noun study has 10 senses (first 8 from tagged texts)
1. (90) survey, study -- (a detailed critical inspection)
2. (17) study, work -- (applying the mind to learning and understanding a subject (especially by
reading); "mastering a second language requires a lot of work"; "no schools offer graduate study in
interior design")
3. (6) report, study, written report -- (a written document describing the findings of some
individual or group; "this accords with the recent study by Hill and Dale")
4. (6) study -- (a state of deep mental absorption; "she is in a deep study")
5. (6) study -- (a room used for reading and writing and studying; "he knocked lightly on the closed
door of the study")
6. (3) discipline, subject, subject area, subject field, field, field of study, study, bailiwick --
(a branch of knowledge; "in what discipline is his doctorate?"; "teachers should be well trained in
their subject"; "anthropology is the study of human beings")
7. (2) sketch, study -- (preliminary drawing for later elaboration; "he made several studies before
starting to paint")
8. (1) cogitation, study -- (attentive consideration and meditation; "after much cogitation he
rejected the offer")
9. study -- (someone who memorizes quickly and easily (as the lines for a part in a play); "he is a
quick study")
10. study -- (a composition intended to develop one aspect of the performer's technique; "a study in
spiccato bowing")
Overview of verb study
The verb study has 6 senses (first 6 from tagged texts)
1. (73) analyze, analyse, study, examine, canvass, canvas -- (consider in detail and subject to an
analysis in order to discover essential features or meaning; "analyze a sonnet by Shakespeare";
"analyze the evidence in a criminal trial"; "analyze your real motives")
2. (17) study -- (be a student; follow a course of study; be enrolled at an institute of learning)
3. (15) study, consider -- (give careful consideration to; "consider the possibility of moving")
4. (13) learn, study, read, take -- (be a student of a certain subject; "She is reading for the bar
exam")
5. (5) study, hit the books -- (learn by reading books; "He is studying geology in his room"; "I
have an exam next week; I must hit the books now")
6. (2) study, meditate, contemplate -- (think intently and at length, as for spiritual purposes; "He
is meditating in his study")
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