Effect of acid etching of retropreparation cavities on seal of retrofill materials / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the effect of acid etching of retropreps on seal of different retrofill materials.@*METHODS@#In the study, 80 freshly extracted lower molar teeth were used. They were examined under 3.5× magnifying glass to rull out fractures. They were cleaned and stored in distilled water before use. The distal roots were sectioned off and underwent root canal treatment. Rotary nickel-titanium instruments were used during instrumentation and the roots were obturated using lateral condensation technique. The apical portion (3 mm in length) was removed with a fine grit diamond bur, the root tip was retroprepared with a ultrasonic tip (3 mm in depth). The retroprepared roots were randomly assigned to 4 groups and retrofilled with amalgam, intermediate restorative material (IRM), iRoot BP Plus and mineral trioxide aggregate (MTA). The groups were further divided into subgroups according to treatment of the root end cavity (etch and non-etch). The root tips were covered with alginate impression material and were left to set in PBS solution for a week and stained with methylene blue for a week. The roots were removed from the dye solution, thoroughly rinsed and dried, split in halves along the long axis with a diamond disk and observed under a stereoscope. The linear dye leakage was measured and analyzed. One way ANOVA and Tamhane's T2 method were used to analyze the data. The significance level was set at 0.05.@*RESULTS@#The dye leakage results (mean±standard deviation) according to the treatment groups were: amalgam etch (2.80±0.72) mm, amalgam non-etch (2.07±0.86) mm, IRM etch (1.54±0.19) mm, IRM non-etch (1.12±0.28) mm , iRoot BP Plus etch (0.20±0.20) mm, iRoot BP Plus non-etch (0.11±0.08) mm, MTA etch (0.19±0.19) mm, and MTA non-etch (0.17±0.14) mm. One way ANOVA showed significant differences between the groups. Comparison between the groups using Tamhane's T2 method showed roots retrofilled with iRoot BP Plus and MTA had significant less leakage than those retrofilled with amalgam and IRM (P<0.05); There was no significant difference in terms of leakage between iRoot BP Plus and MTA; Acid etching increased leakage of IRM but did not affect MTA, iRoot BP Plus or amalgam retrofillings.@*CONCLUSION@#Acid etching is not shown to benefit apical sealing of retrofill materials.

Temperature variation at the external root surface during Nd: YAG laser irradiation in the root canal in vitro / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To assess the temperature variation of the root surface using Nd: YAG laser irradiation in the root canal with different power and to evaluate the safety of laser application on the periodontal region.</p><p><b>METHODS</b>Thirty extracted human teeth with single-roots were collected. The teeth were cross-sectioned in the cervical portion, standardizing the roots at a 12-mm length. The roots were used as specimen. The roots were radiographed in the buccal-lingual direction to measure the thickness of the proximal walls, by means of a digital radiographic system. The specimens were divided into three groups according to the laser potency (1.5, 3.0, and 4.5 W). Each group was subdivided into two subgroups according to laser frequency (15 and 30 Hz). With the Nd: YAG laser irradiation for 20 s, the temperature variation of the root surface was monitored by thermocouples located at different parts of the root external wall and recorded by digital thermometers.</p><p><b>RESULTS</b>The groups irradiated with 4.5 W presented the greatest temperature variation (above 10°C), followed by 3.0 and 1.5 W. The temperatures were statistically different (P < 0.01). The groups irradiated in the same potency, regardless of whether 15 Hz or 30 Hz was used, presented with no statistical difference (P > 0.05). The apical half of the root presented statistically higher temperature rises than the cervical half of the root (P < 0.01).</p><p><b>CONCLUSION</b>The temperature variation of the root surface was associated with laser power, irradiation time, and the thickness of dentin. Application of Nd: YAG laser in the root at 1.5 W for 20 s can safely be used in endodontic treatment.</p>

Clinical evaluation of large periapical lesions following apical surgery / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the therapeutic effect of teeth with large periapical lesions followed apical surgery.</p><p><b>METHODS</b>59 patients (59 periapical lesions, 91 teeth) with large periapical lesions ranging in size from 6 mm to 21 mm in diameter were included in this study. All teeth were treated by root canal therapy and apical surgery, and the surgical procedure was completed with microsurgical technology and ultrasonic root-end preparation. The outcomes were evaluated clinically and radiographically at 1, 3, 6, 9, 12 and 24-month intervals, and the various factors which may affect the success rate were analyzed statistically.</p><p><b>RESULTS</b>52 cases (88.1%) of 59 patients were considered success, 6 cases (10.2%) were considered failure, and 1 case (1.7%) was considered in progress. The success rate of elderly patients group (63.6%) was significantly lower than that of the youth group (87.5%) and middle-aged group (95.0%) (P = 0.037; P = 0.017). The success rate of molar group (75.0%) was significantly lower than that of the anterior group (92.6%) and the premolar group (90.0%) (P = 0.041, P = 0.047); however, there was no significant difference in the gender, the number of teeth invaded in lesions, the size of periapical lesion (P > 0.05).</p><p><b>CONCLUSION</b>It is an effective therapy for the teeth with large periapical lesions by apical surgery after root canal treatment.</p>

Clinical evaluation on the root canal therapy bypassing intracanal separated instruments / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study and evaluate the clinical effect of root canal therapy bypassing intracanal separated instruments.</p><p><b>METHODS</b>32 teeth were selected as the test group, from which the intracanal separated instruments couldn't be taken out, adopted the method of root canal preparation and obturation bypassing broken instruments. Meanwhile, 13 teeth were selected as the control group, in which the fractured instruments couldn't be taken out from root canal, and not be cured bypassing broken instruments. 30 teeth were selected as the conventional therapy group, in which the instruments were not fractured, the routine root canal therapy were adopted. The clinical efficacy of three groups were observed and evaluated through periapical index and clinical examination two years later.</p><p><b>RESULTS</b>After two years, 25 teeth were followed up in test group, the success rate of root canal therapy was 80.00%; 11 teeth were followed up in control group, the success rate of root canal therapy was 36.36%. All of the failed cases in two groups were the teeth with broken instruments in tip of root canal. In conventional therapy group, 22 teeth were followed up, and the success rate of root canal therapy was 90.91%.</p><p><b>CONCLUSION</b>Root canal therapy bypassing intracanal separated instruments is a feasible and effective method in treating the teeth with broken instruments.</p>