Effect of different irrigation activation methods on non-infected dentinal tubule penetration of medicaments: A CLSM study.

Background: The whole root canal disinfection is crucial in terms of long-term endodontic success. In this context, applying medicaments following effective irrigation activation procedures becomes an important point. Aims: The purpose of this study was to evaluate and compare the efficacy of various irrigation activation techniques on non-infected dentinal tubule penetration of calcium hydroxide (CH), double (DAP), and triple (TAP) antibiotic pastes. Materials and Methods: A total of 180 extracted human permanent mandibular premolar single-rooted teeth were selected and randomly divided into a control group and four main groups according to the irrigation activation procedures (n = 36) as KTP laser irradiation, conventional needle, NaviTip FX, sonic (SI) and ultrasonic activation (UI) procedures. Each group was randomly subdivided into three subgroups according to the medicament type (n = 12); CH, DAP, and TAP. After the activation procedures, the root canals were filled with CH, TAP, and DAP mixed with 0.1% fluorescent rhodamine B isothiocyanate. Specimens were sectioned at 2, 5, and 8 mm from the apex, and all the sections were examined under a confocal laser scanning microscope to calculate the dentinal tubule penetration. Data were analyzed using a three-way analysis of variance and Tukey's post hoc tests (P = 0.05). Results: TAP provided a statistically significant greater penetration than the other groups (P < 0.05). UI provided a statistically significant higher dentinal tubules penetration area than other activation procedures (P < 0.05). Conclusion: Medicament penetration depends on the type of medicament, activation procedures, and root canal level. The TAP may be preferred following the ultrasonic activation in terms of long term root canal treatment success.

Evaluating efficacy of different post materials and lengths on bonding strength between root canal dentin and post restorations: An experimental study.

BACKGROUND: During post restoration, different root structures require several types of posts to increase duration of their clinical use. Several materials have been investigated to enhance their quality and optimize their length according to the available root canal. AIMS: The aim of this study was to determine the effect of zirconia, fiber, and ceromer posts with 3- and 6-mm post sizes on the bonding strength of them to root canal dentinal wall with the means of pull-out bond strength test. METHODS: Forty-eight single-rooted mandibular human premolar teeth were collected and prepared for this in vitro study. With resin cement, 3- and 6-mm study posts including zirconia, fiber, and ceromer were luted to prepare teeth. For the retention testing, the pull-out force was applied to each specimen parallel to longitudinal axis of both the post and tooth. RESULTS: Both type of materials and size of posts changed the value of bonding strength. In all the post types, 6-mm ones performed better. Overall, the best bonding strength was obtained with fiber posts and the better bonding strength was obtained with zirconia; however, ceromer provided the least bonding strength. CONCLUSION: Current experiments supported that 6-mm post size can increase the bonding between root canal dentin and studied posts. When considering post materials, fiber provided the best bonding strength in current laboratory setup. Second, zirconia had meaningfully acceptable bonding strength; however, the bonding strength of ceromer posts was not favorable. Further studies optimizing post fabrication techniques of root materials may increase the bonding strength of posts to human dentin to an acceptable clinical degree.

Importance of disinfection time and procedure with different alginate impression products to reduce dimensional instability.

AIMS: The aim of this study was to determine the best approach to reduce the unfavorable change in the three different dimensions of impressions using disinfection durations of 15 and 30 min; three different disinfection procedures; and alginate impression products as research factors. MATERIALS AND METHODS: CA37, impressional, and cream alginate impressions were used; distortion in the AB, AC, and BC dimensions of impressions using disinfection durations of 15 and 30 min was studied; and no disinfection (ND), conventional disinfection (CD), and sonicator-activated disinfection (SAD) procedures were measured. RESULTS: Regarding AB dimension, the impressional has best performance when CD was applied for both 15 and 30 min. When SAD was applied for 15 min, impressional and cream alginates provide best performance. When CD was applied for 15 min, CA37 and impressional alginates provide best performance. Although ND-applied CA37 alginate after 30 min provides best performance, because of many outlier values, its implication may not be considered as meaningful. Regarding AC dimension, cream alginate has best performance when CD was applied for 15 min. The AC distances in all the alginates are considerably different from the base model after 30 min. Regarding BC dimension, only the CA37 alginate has the best performance when ND was applied for 15 min. All the alginates are considerably different from that of the base model after 30 min. CONCLUSION: Preference of 15-min disinfection can provide favorable results to obtain all impressions with minimally distorted dimensions. CD is an adequate procedure. The studied SAD needs to be developed further. All alginates are comparably successful to obtain impressions with desired distortion degrees.