Purpose: To evaluate the results of laser in situ keratomileusis (LASIK) RETREATMENT in patients with postoperative regression.Methods: In a retrospective interventional case series, 153 eyes of 113 patients who had undergone LASIK RETREATMENT for postoperative regression were evaluated. Both initial LASIK and RETREATMENT were performed with a Nidek: EC 5000 excimer laser and flap was made with a Moria microkeratome.Results: Mean age was 29.63 ± 2.2 yr (range, 20 to 54 yr) and mean follow–up was 11 months (range, 3 to 34mth) after the initial surgery and 13.1 months (range, 12 to 18mth) after RETREATMENT. RETREATMENT was performed 3-34 months after the primary LASIK. Mean spherical equivalent (SE) was -5.39 ± 2.69 diopters (D) (range, -1.50 to -14.00 D) before initial LASIK and -1.76 ± 1.08 D (range, -0.50 to -5.00 D) before RETREATMENT. Mean astigmatism was -1.38 ± 1.07 D (range, -0.50 to -5.00 D) before initial LASIK and -1.12 ± 0.50 D (range, -0.50 to -2.50 D) before RETREATMENT. One year after RETREATMENT, mean UCVA was 20/25, and mean SE was -0.29 ± 0.02 D. Best corrected visual acuity (BCVA) improved in all eyes. Two eyes received more than one RETREATMENT. Twenty eyes had flap wrinkling, 2 eyes had diffuse lamellar keratitis (DLK), and 2 eyes had epithelial in growth after the initial LASIK. Four eyes had epithelial in growth and 2 eyes developed mild keratectasia after RETREATMENT.Conclusions: LASIK RETREATMENT is a safe and effective option with small amounts of myopia and myopic astigmatism regression. The rate of RETREATMENT is higher in patients with myopic astigmatism and in patients with less than 40 years of age; also the risk of complications in RETREATMENT is higher than the initial LASIK. Refractive changes are more stable after RETREATMENT. The risk of keratectasia is higher in final residual stromal bed thickness less than 250 mm after the reoperation.

Introduction: One of the most important reasons of endodontic failure is the persistence of microbial factors in the root canal system. Therefore, three-dimensional cleaning of the root canal space is very important to eliminate or reduce the irritant factors and microorganisms.Objective: To evaluate the effectiveness of Mtwo R and ProTaper RETREATMENT files as compared with Mtwo and ProTaper files in RETREATMENT of the gutta-percha filled root canals.Materials and Methods: In this in-vitro study, fifty extracted single root premolars with approximately straight and similar root lengths were selected. Primary preparation of the root canals was performed by ProTaper rotary system and all of the roots were filled by lateral condensation technique. Then, the teeth were randomly divided into five groups, and each group was retreated with one of the ProTaper, ProTaper RETREATMENT, Mtwo, Mtwo R systems and hedstrom hand files. Following the longitudinal splitting of the roots with diamond discs and evaluation of amount of the gutta-percha/ sealer on the root canal walls with stereomicroscope. Obtained results were analyzed with kruskal-wallis and Mann- Whitney u tests.Results: Complete removal of gutta-percha/ sealer did not occur with any of the investigated systems .There is significant statistical differences between test groups at the apical and middle thirds of canals(P=0.849, P=0.315 respectively ).In Hedstrom group, significantly less filling material was observed in the coronal third of canals. Regardindg the duration of RETREATMENT, all of the rotary systems were significantly more rapid than hand files. Rotary files that were specifically designed for RETREATMENT, were significantly more rapid than universal ProTaper.Conclusion: Despite this fact that neither of used techniques in this study were able to remove the filling material completely, but regarding to higher speed and probability of less fracture of the files specifically designed for RETREATMENT (Mtwo R and ProTaper RETREATMENT) as compared with universal rotary files (Mtwo R and ProTaper), we suggested that these files can be appropriate choice for root canal RETREATMENT.

Purpose: Refractive surgery complications can include refractive errors undercorrection and regression. Based on the studies, undercorrection and regression are the most common complications after refractive surgery. The aim of this study is to determine the refractive and visual results in patients with PRK RETREATMENT. Methods: In this case series study, a total of 30 eyes of 20 patients were studied. The parameters evaluated were visual acuity and refraction. The mean patient’ s age were 34. 5± 5. 9 years. The original treatments and subsequent RETREATMENT were performed by the same surgeon at Farabi Eye Hospital. SPSS 20 statistical software was used to analyze the data. At first, the normality of the data distribution has been tested by Kolmogorov-Smirnov test. Subsequently, The Paired-Samples T Test and Wilcoxon signed-rank test have been used to compare the means of variables. Results: The spherical and astigmatism refractions prior to PRK RETREATMENT were-0. 80 ± 0. 67 diopters (D) and-0. 70 ± 0. 36 diopters (D) respectively, and after PRK RETREATMENT were change to-0. 16 ± 0. 69 diopters (D) and-0. 49 ± 0. 61 diopters (D) respectively. The Logarithm of MAR uncorrected distance visual acuity (UCVA) and best corrected distance visual acuity (BCVA) prior to PRK RETREATMENT were 0. 28367 ± 0. 25104, 0. 01667 ± 0. 06064 respectively and after PRK RETREATMENT were 0. 08167 ± 0. 241148, 0. 04467 ± 0. 237149 Log MAR. Conclusion: PRK RETREATMENT can significantly improve UCVA and decrease residual refractive errors without significant complications. PRK is a useful, safe and effective method for RETREATMENT residual refractive errors.

Introduction: Advantages of endodontic treatments over tooth extraction have increased the demands for these treatments. Success rate of these treatments is generally lower than the primary root canal therapies. Recently, single visit treatments have gained more popularity. But, the influence of completing RETREATMENT in a single appointment on success of the treatment is still a controversy. The aim of this study was evaluating the most common causes offailures and determining the success rate of completing RETREATMENTs in single appointment.Materials and Methods: Hundred and twenty four patients who had single appointment RETREATMENT within past 4 years in postgraduate ward of Shaheed Beheshti Dental School were selected and clinical and radiographic examinations were carried out. The data were analyzed by SPSS using Chi-square and Exact Fisher tests.Results: Success rate and uncertain cases were shown to be 50.7% and 34.2%, respectively and failure rate was 15.1 %. Presence of periradicular lesion or history Of swelling prior to RETREATMENT had significant effect on the success of single visit retreatrnents (p<0.001). Another important finding of the study was that the success rate of RETREATMENTs was significantly higher in cases, referred for restorative purposes compared with retreatrnents for nonrestorative purposes (p<0.001).Conclusion: The overall success rate of single appointment RETREATMENTs is up to 84.9% which is considerably higher in cases referred for restorative purposes. So based on the results of this study single appointment RETREATMENT of symptom less teeth is recommended.

Introduction: Different techniques have been proposed to help achieving apical patency during endodontic treatment and RETREATMENT. The objective of this in vitro study was to compare reestablishment of apical patency in teeth previously subjected to root canal treatment using manual and reciprocating instruments. Methods and Materials: A total of 40 single-rooted extracted human mandibular incisors were selected and prepared using the Hero 642 sequence to 45/0. 02 and obturated using Tagger’ s hybrid technique to 1 mm short of the apex. Teeth were divided into two groups according to the type of instrument used to regain patency: group 1, hand K-files and group 2, reciprocating WaveOne Primary files (25/0. 08). Fisher’ s exact test was used in the statistical analysis. Result: In group1, apical patency was regained in 9 of the 20 teeth tested (46%), compared to 20 teeth (100%) in group 2. The difference between the groups was significant (P<0. 0001). Conclusion: Our study shows that reciprocating instrumentation is more successful in regaining apical patency in single-rooted, previously treated teeth.

Introduction: Pharmacotherapy with analgesics and non-steroidal anti- inflammatory drugs has been traditionally used to relief post- operative pain of endodontic treatments. However, due to the side effects reported for these drugs, some efforts have been made to decrease the post- operative pain of the endodontic treatments through laser irradiation. The present study aimed to evaluate the effects of low level laser therapy (LLLT) on the reduction of pain after root canal RETREATMENT.Methods: In this clinical trial, 61 patients requiring endodontic RETREATMENTs in posterior teeth were selected. A single visit endodontic RETREATMENT was performed. After biomechanical preparation, low level laser was irradiated to the buccal and lingual mucosa overlying the apices of the target tooth in the experimental group. In the control group patients received placebo laser to eliminate the probable psychological effects of laser. Laser irradiation was done with a single dose of 808 nm wavelength (Whitening Lase II- Laser DMC, Samsung, Korea) with 100 mW power, and dose of 70 J/cm2 for 80 seconds. Pain severity was recorded before, immediately after and 4, 8, 12, 24 and 48 hours after the treatment by visual analogue scale (VAS). The pain scores were statistically analyzed by chi- square test between 2 groups. The effects of different variables on the post-operative pain experience were also studied by means of Logistic regression. Results: Pain scores decreased significantly through time until 48 hours after treatment. No significant differences were observed between the 2 modalities regarding pain scores at any time. According to regression analysis, pain severity scores were lower in the laser-irradiated specimens than control groups (OR=5.69); however, this difference was not statistically significant. Consumption of analgesics after the treatment had significant effect in decreasing post-operative pain experience (OR=56) while factors of age, gender, laser irradiation, pre- treatment pain scores and education level did not.Conclusion: Low level laser irradiation had limited effects to decrease pain associated with the endodontic RETREATMENTs in the first and second molars; however, more studies are required to assess the effects of different parameters of low level laser in this regard.

Introduction: The aim of the present ex vivo research was to compare the remaining filling material and the volumes of dentine removed after RETREATMENT of curved canals with two rotary systems naming ProTaper Universal RETREATMENT and Mani NRT-GPR using micro-computed tomography (micro-CT). Methods and Material: Forty mandibular molars containing two completely separated canals, with curvature angle of 25-35° and a curvature radius <10 mm were prepared to the Mtwo instrument 35/0. 04 and filled with warm gutta-percha and AH-Plus sealer. The teeth were randomly divided into 2 groups (n=20), according to the RETREATMENT system evaluated: ProTaper Universal RETREATMENT (PR group) or Mani NRT-GPR (MR group). RETREATMENT was considered complete when the working length was reached and when smooth dentinal walls were observed, with no evidence of filling material adhered to instruments or in the irrigating solution. Preoperative and postoperative micro-CT images were obtained with an isotropic voxel size of 11. 88 μ m to observe the volume of residual filling material in the canals and dentine removed after RETREATMENT. Statistical analysis was performed by Student’ s t-test (P<0. 05). Results: The mean percentage of remaining filling material was 12. 96% for PR group and 24. 26% for MR group (P=0. 0056). The percentage of dentin removal was greater in the PR group (5. 02%) than MR group (1. 36%) (P=0. 0028). Both systems failed to completely remove the filling material from the canals. Conclusion: ProTaper Universal RETREATMENT system was more effective than Mani NRT-GPR system regarding removal of root filling material and also removed significantly more dentine after RETREATMENT of curved mesial root canals of mandibular molars.

Mandibular premolars have earned a reputation for having aberrant anatomy. The occurrence of three canals with three separate foramina in mandibular premolars is very rare. If predictable treatment of a three rooted mandibular premolar is planned, precise knowledge of clinical and radiographic anatomy is absolutely necessary. These teeth may also require special shaping and obturating techniques. This article reports and discusses the treatment recommendations for an unusual occurrence of three canals with three separate foramina in a second mandibular premolar.