Peter Z. Tawil

Periapical Microsurgery: An In Vivo Evaluation of Endodontic Root-End Filling Materials

The purpose of this study was to assess the healing of periapical tissues using three different materials (IRM [L.D. Caulk Inc, Dentsply International Inc, Milford, DE], Geristore [Den-Mat, Santa Maria, CA], and MTA [ProRoot MTA; Dentsply Tulsa Dental Specialties, Tulsa, OK]) after endodontic microsurgery in an animal model. Using beagle dogs as a study model, 48 bicuspids were accessed, instrumented, and intentionally infected. The surgical procedures were performed after 30 days following the radiographic confirmation of periapical radiolucencies. The root canals were still infected and had no disinfection procedure carried out. The root ends were resected, retrograde preparations were completed, and the experimental materials were placed under surgical operating microscopy. After a period of 6 months, digital radiographic images of the periradicular areas were taken. The samples were prepared for histologic evaluation. Although Geristore showed no radiographic difference when compared with the other groups, it showed the least favorable healing in the histologic evaluation. Our histologic and radiographic results showed no statistical difference between MTA and IRM.

Effect of intracanal corticosteroids on healing of replanted dog teeth after extended dry times.

This study investigated the effect of potent intracanal corticosteroids on periodontal healing of replanted avulsed teeth and evaluated the systemic absorption of these corticosteroids. Sixty-seven extracted dog premolar roots were randomly assigned to one of the following groups: groups 1-3 filled with gutta-percha and replanted immediately and after 40 and 60 minutes, respectively; groups 4 and 5 filled with 0.05% clobetasol; and groups 6 and 7 filled with 0.05 % fluocinonide. Groups 4 and 6 were replanted after 40 minutes and groups 5 and 7 after 60 minutes. After 4 months, roots were evaluated histologically for signs of periodontal healing. Roots treated with clobetasol and fluocinonide healed more favorably than roots filled with gutta-percha and were different from each other at 60 minutes. No change in the systemic corticosteroid blood concentration was observed in any group. Corticosteroids were efficacious in the beagle model as intracanal medicaments for promoting favorable postavulsion periodontal healing.

Periapical inflammation and bacterial penetration after coronal inoculation of dog roots filled with RealSeal 1 or Thermafil.

INTRODUCTION The purpose of this study was to subject 2 carrier-based root filling products to a 4-month microbial challenge in a dog model with histologic markers to assess periapical inflammation and bacterial penetration of the 2 filling materials. Histologic evidence of bacterial penetration and periapical inflammation were the outcome parameters used to compare the products. METHODS Teeth were aseptically prepared and then filled with carrier-based Resilon (RealSeal 1 [RS-1], n = 25) or with carrier-based gutta-percha (Thermafil, n = 25) and were left exposed for 4 months. The first control group received a coronal seal over either RS-1 or Thermafil root fillings (n = 8). A second control group was instrumented and left completely empty (n = 8). RESULTS Histologic evidence of periapical inflammation was observed in 29% of the Thermafil group and in 9% of the RS-1 group. This difference was only significant when controlling for a possible tooth position effect on inflammation presence (P < .05). Histologic evidence of bacterial penetration was present in 9% of the RS-1 group and in 70% of the Thermafil group. The difference in penetration rates between RS-1 and Thermafil was statistically significant when controlling for any dog or tooth position effects on bacterial penetration (P < .001). Furthermore, there was a statistically significant correlation between histologic evidence of inflammation and histologic evidence of infection (P = .002). CONCLUSIONS RS-1 appeared to resist bacterial penetration more effectively than Thermafil under the conditions of this study.

Periapical Microsurgery: Can Ultrasonic Root-end Preparations Clinically Create or Propagate Dentinal Defects?

INTRODUCTION This clinical study evaluates the effect of ultrasonic root-end preparations on dentinal defect creation and propagation. METHODS Eighty-four teeth were treated with periapical microsurgery using a modern microsurgical protocol in a private practice setting. The root apices were resected and inspected for dentinal defects with a surgical operating microscope and a 0.8-mm diameter light-emitting diode microscope diagnostic probe light, both before and after ultrasonic root-end preparations. A 3-grade scale (none, partial, and full dentinal defect) was used to assess the status of the roots before and after ultrasonic root-end preparation. RESULTS Of the 84 treated teeth, 3 had a vertical root fracture, leaving a total of 81 teeth for assessment. Fifty-one teeth were intact upon resection and remained intact after root-end preparation. Twenty-six teeth had partial dentinal defects, and 14 (54%) of these propagated into full dentinal defects after root-end preparation. CONCLUSIONS This periapical microsurgery study showed that ultrasonic root-end preparations are safe to use on intact roots. Preexisting dentinal defects can be propagated by ultrasonic root-end preparations. Through the use of light-emitting diodes, dentinal defects can be detected, special root-end management can be implemented, and more predictable outcomes may be achieved.

Light-emitting diode assessment of dentinal defects: the role of presumed extraction forces.

Objectives The evaluation of iatrogenic dentinal defects in extracted teeth may be influenced by extraction forces and prolonged dry times. The purpose of this study was to compare the presence of dentinal defects in freshly extracted, periodontally compromised teeth with those in a group of teeth with uncontrolled extraction forces and storage time. Materials and Methods The experimental group consisted of eighteen roots obtained from teeth extracted due to periodontal reasons with class II or III mobility. They were kept in saline and sectioned within 1 hour following extraction. The control group consisted of matched root types obtained from an anonymous tooth collection, consistent with previous dentinal defect studies. The slices were obtained at 3, 6, and 9 mm from the apex. The imaging process exposed all specimens to no more than 60 seconds of dry time. The × 12.8 magnification was used for the 9 mm slices and × 19.2 magnification for the 3 mm and 6 mm slices under light-emitting diode (LED) transillumination. The root canal spaces and periodontal tissues were masked to minimize extraneous factors that might influence the evaluators. Chi-square test was used for statistical analysis. Results Dentinal defects were detected in 17% of the experimental group teeth, compared to 61% of control teeth (p = 0.015). Conclusions LED transillumination assessment of freshly extracted roots with class II or III mobility showed smaller number of dentinal defects than roots with uncontrolled storage time and extraction forces. The use of freshly extracted roots with mobility should be considered for future dental defect assessment studies.

Periapical Microsurgery: Do Root Canal–retreated Teeth Have More Dentinal Defects?

Introduction This microsurgical clinical study evaluated if teeth that have undergone endodontic retreatment are associated with more dentinal defects than primary root canal–treated teeth. Methods One hundred fifty‐five patients who underwent periapical microsurgery treatment in a private practice setting were evaluated. The root ends were resected, and the roots were inspected for the presence of dentinal defects through the surgical operating microscope with the help of a 0.8‐mm‐diameter light‐emitting diode probe light and methylene blue dye. The root canal treatment history (primary vs retreatment) of the teeth was documented and related to the presence or absence of dentinal defects. Bivariate analysis was performed using the chi‐square test, and a multivariate analysis was performed using logistic regression to evaluate possible confounding effects of patient age, sex, and tooth location on the association between treatment and the presence of dentinal defects. Results Of the 155 treated teeth, 33 were excluded (3 fractured and 30 missing treatment history). Of the remaining 122 included teeth, 73 (59.8%) had undergone primary root canal treatment and 49 (40.2%) retreatment. Sixteen teeth (22.5%) of the primary root canal group versus 33 (64.7%) of the retreatment group had dentinal defects. The proportion of retreated teeth with dentinal defects compared with primary treatment was statistically significant (P < .001) with a higher proportion of retreated teeth having dentinal defects. In the multivariate analysis, only the type of treatment was statistically significant (P < .001). Conclusions This clinical study showed that root canal–retreated teeth are associated with more dentinal defects than primary root canal–treated teeth.

Nominal Size and Taper Analysis of Novel Metallurgy NiTi Files

Objective: The aim of this investigation was to assess the nominal tip diameter, taper and true pilot tip length of three nickel-titanium (NiTi) rotary files before and after use. Methods: Three brands of NiTi files of size 25.08 were evaluated: ProTaper Uni-versal (Dentsply Tulsa Specialties, Tulsa, USA), Channels PT (Insight Endo for Henry Schein, Melville, NY) and ProTaper Gold (Dentsply Tulsa Specialties), with ten files from each brand (total n=30). Scanning electron microscope (SEM) images of the files at 50x magnification were acquired before and after the files were used on endodontic training blocks, and the images were analysed by two independent investigators using ImageJ software. The nominal tip diameter (D0), taper and true pilot tip length (measured as the distance from the advertised diameter size of the file to the tip of the file) were recorded for each file and were analysed for statistical differences using repeated measures of analysis of variance (r-ANOVA) and Tukey’s post-hoc test (P<0.05). Results: The marginal means of the nominal size showed statistically significant differences between brands of the same size; statistically significant differences were also observed between the advertised sizes and the actual sizes (P<0.001). The mean taper values showed statistically significant differences from the advertised (p<0.001) sizes, except for the ProTaper Gold (P=0.023) group. The changes in the true pilot tip length before and after use were not statistically significant (P>0.05). The pilot tip lengths varied between brands. Conclusion: All nominal tip diameters and most taper sizes of the analysed brands show statistically significant differences from the nominal sizes advertised by the manufacturers. The differences in true pilot tip lengths between brands indicate a current lack of standardization.