Evaluation of apically extruded debris during root canal filling material removal in teeth with external apical root resorption: a comparison of different obturation techniques.

BACKGROUND: Root canal retreatment is necessary when initial treatment fails. Nickel-titanium systems help remove filling materials; however, some methods can cause canal content extrusion, resulting in inflammation and delayed healing. This study aimed to examine the impact of different preparation techniques and endodontic file systems on apical debris volume to limit material dispersion to periradicular tissues. METHODS: Ninety extracted maxillary incisors were evaluated. Simulated apical root resorption was created by removing the apical 2 mm of the root. The teeth were divided into two groups: one filled with a single cone and the other with cold lateral compaction (CLC). Each group was further divided into three subgroups (n = 15 each): Subgroup 1 used Reciproc R25 for removal and R50 for final preparation; Subgroup 2 used ProTaper Universal Retreatment (PTUR) files D1, D2, and D3 for removal and ProTaper Next X5 for finalization; and Subgroup 3 used VDW.Rotate Retreatment (VDW.RotateR) for removal and VDW.Rotate 50.04 for completion. Debris from retreatment was collected in pre-weighed tubes to determine the amount. The apical extrusion data underwent a two-way analysis of variance. RESULTS: The Reciproc group had a mean extruded debris weight of 0.54 ± 0.24 mg, higher than the PTUR (0.28 ± 0.15 mg) and VDW.RotateR (0.39 ± 0.29 mg) groups (p < 0.05). The single-cone technique (SCT) resulted in a mean debris weight of 0.34 ± 0.23 mg, lower than the CLC technique, which had a mean of 0.46 ± 0.27 mg (p < 0.05). SCT had a shorter retreatment duration (111.12 ± 33.46 s) compared to CLC (176.26 ± 52.26 s) (p < 0.05). CONCLUSION: The Reciproc file system and the CLC obturation technique resulted in greater apical debris extrusion than the other methods. SCT was quicker than CLC. The Reciproc groups are more susceptible to apex extrusion during retreatment.

Four-year Outcomes of Class III and IV Anterior Restorations Based on a Subset of German Health Insurance Data.

PURPOSE: Numerous studies report on the outcome performance of posterior composite restorations. However, there are fewer studies providing data for anterior restorations. The aim of this study was to evaluate the clinical outcome performance of anterior permanent restorations by analyzing a large dataset from a German national health insurance company. MATERIALS AND METHODS: Routine claims data from a major German national health insurance company were assessed. Fee codes were used for tracing restoration careers on a day-count basis. The treatment was defined as a placed restoration (Class III and IV) on a mesial or distal tooth surface, irrespective of the extension. The restorations were placed between January 1, 2010 and December 31, 2013. Statistical analyses were conducted using Kaplan-Meier survival analysis to determine cumulative 4-year survival rates. The primary outcome was re-intervention on the same surface. Secondary outcomes were crowning and extraction which were analyzed separately. RESULTS: A total of 2,417,791 restorations involving mesial surfaces and a number of 2,409,031 restorations involving distal surfaces were observed. At 4 years, the cumulative survival rates concerning the primary outcome 're-intervention' were 79.9% for mesial and 80.9% for distal restorations. The respective annual failure rates (AFR) were 5.5% and 5.2%. Four-year survival rates for the secondary outcome 'crown' were 93.8% for mesial and 94.1% for distal anterior restorations. The respective AFRs were 1.6% and 1.5%. For the secondary outcome 'extraction,' the respective rates were 94.6% for mesial and 93.9% for distal restorations. The respective AFRs were 1.4% and 1.6%. CONCLUSION: The performance of permanent anterior restorations which were placed in general dental practices in Germany can be rated as acceptable.

Comparative evaluation of the accuracy of electronic apex locators and cone-beam computed tomography in detection of root canal perforation and working length during endodontic retreatment.

BACKGROUND: To evaluate the accuracy of the electronic apex locators (EALs), and Cone-Beam Computed Tomography (CBCT) scanning, both in working length (WL) determination and in the detection of root canal perforations in retreatment cases. METHODS: Sixty human mandibular premolars were selected. After crown removal partially and canal access, root canals were instrumented and irrigated. The obturation process utilized gutta-percha and sealer with warm vertical compaction. Two groups were distinguished: one without perforation (Group 1) and the other with an apical third perforation (Group 2). Retreatment included filling removal, apical preparation, and irrigation. Actual working lengths (AWL) were determined using a stereomicroscope. CBCT images were used to measure CBCT working length (CWL), with adjustments for optimal views. Propex II and Dentaport ZX were used to measure electronic working length (EWL). Differences between EWL and AWL, as well as CWL, were analyzed to gauge accuracy. Data underwent Two-way ANOVA analysis. Measurements within ± 0.5 and ± 1 mm tolerance ranges were deemed successful for each device, followed by applying the Pearson Chi-square test. RESULTS: The study reveals no significant inter-group variations in device performance (p > .05). Dentaport ZX missed detecting perforation in two Group 2 (apical perforation) cases. For ± 1 mm tolerance, Propex II displayed the highest success in Group 2 (apical perforation). CONCLUSION: This study demonstrates the comparable performance of Propex II, Dentaport ZX, and CBCT in endodontic retreatment, providing insights into diagnostic reliability.

Postoperative pain in oncological patients subjected to nonsurgical root canal treatment: a prospective case-control study.

OBJECTIVES: The purpose of this prospective study was to evaluate the incidence and intensity of postoperative pain in oncological patients with infected teeth subjected to nonsurgical root canal treatment or retreatment. METHODS: Teeth with apical periodontitis from healthy control patients and oncological patients (n = 70 per group) were root canal treated/retreated and evaluated for the development of postoperative pain. Patients from the two groups were matched for tooth type, gender, clinical manifestation of apical periodontitis, and intervention type. A visual analogue scale (VSA) was used to evaluate the incidence of postoperative pain at 24 h, 72 h, 7d, and 15d after chemomechanical procedures. Data were statistically analyzed for the incidence and intensity of postoperative pain in the two groups. RESULTS: Preoperative pain occurred in 10% of the individuals and in all these cases pain showed a reduction in intensity or was absent after endodontic intervention at 24-h evaluation. The overall incidence of postoperative pain at 24 h was 14% in oncology patients and 30% in controls (p = 0.03). At 72 h, the respective corresponding figures were 4% and 8.5% (p > 0.05). At 7 and 15 days, all patients were asymptomatic, irrespective of the group. CONCLUSIONS: No significant differences in postoperative pain were found between control and oncological patients. The low incidence of postoperative pain observed in both groups supports the routine use of nonsurgical root canal treatment/retreatment as valid options in oncological patients. CLINICAL RELEVANCE: Oncological patients had no increased risk of postoperative pain in comparison with control patients.

Association of Fine Particulate Matter and Residential Greenness With Risk of Pulmonary Tuberculosis Retreatment: Population-Based Retrospective Study.

Background: The evidence on the association of fine particulate matter with an aerodynamic diameter of 2.5 µm or less (PM2.5) with pulmonary tuberculosis (PTB) retreatment is limited. There are no data on whether greenness exposure protects air pollution-related PTB retreatment in patients with prior PTB. Objective: In a population-based retrospective study, we aimed to investigate the influence of PM2.5 and residential greenness on the risk of PTB retreatment. Methods: A total of 26,482 patients with incident PTB, registered in a mandatory web-based reporting system between 2012 and 2019 in Zhengzhou, China, were included in the analysis. The exposure to PM2.5 was assessed based on the China High Air Pollutants dataset, and the level of greenness was estimated using the Normalized Difference Vegetation Index (NDVI) values. The associations of PTB retreatment with exposure to PM2.5 and greenness were evaluated, respectively, considering the local socioeconomic level indicated by the nighttime light index. Results: Among the 26,482 patients (mean age 46.86, SD 19.52 years) with a median follow-up time of 1523 days per patient, 1542 (5.82%) PTB retreatments were observed between 2012 and 2019. Exposure to PM2.5 was observed to be significantly associated with the increased risk of PTB retreatment in fully adjusted models with a hazard ratio of 1.97 (95% CI 1.34-2.83) per 10 µg/m3 increase in PM2.5. Patients living in the regions with relatively high quartiles of NDVI values had a 45% lower risk of PTB retreatment than those living in the regions with the lowest quartile for the 500 m buffers (hazard ratio 0.55, 95% CI 0.40-0.77). Such a protective effect of residential greenness was more pronounced among patients living in lower nighttime light areas. The strength of the association between PM2.5 exposure and the risk of PTB retreatment was attenuated by greenness. No significant association was observed between NDVI and the incidence of drug resistance. Conclusions: Long-term exposure to PM2.5 might be a risk factor for PTB retreatment, while an increased level of residential greenness was found to be associated with reduced risks of PTB retreatment. Our results suggest strengthening the control of ambient air pollution and improving residential greenness may contribute to the reduction of PTB retreatment.

Residual vertical defects: risk of disease progression, retreatment rates, and cost: a retrospective analysis.

OBJECTIVES: This study aimed to explore the relationship between Radiographic Residual Vertical Defects (RVDs) and the progression of periodontitis in patients undergoing periodontal maintenance therapy (PMT). MATERIALS AND METHODS: Teeth with RVDs were compared to the same contralateral teeth in the same patient. The study investigated the effect of smoking, diabetes, compliance, disease Stage, and Grade, baseline probing depth (PD), periodontal risk score (PRS), baseline pocket closure (PC) (≤ 4 mm), and tooth mobility on disease progression. We calculated the need for retreatment during PMT and its associated cost. Generalized estimation equations and linear and multilevel logistic regression analyses were employed for data analysis. RESULTS: Each group had 139 teeth, accounting for 80 patients. Although the group with RVDs had similar PD reduction compared to the control teeth, the prevalence of PC at the last follow-up was reduced to half in the RVDs group (odds ratio OR = 0.5; p-value = 0.028), regardless of PC status at the baseline. RVDs were also significant predictors of tooth loss due to periodontitis (TLP), with an OR of 2.28 (p = 0.043). Patients with diabetes, Stage IV, higher mobility, and higher PRS scores had a higher risk of tooth loss due to periodontitis (OR = 4.71, 3.84, 3.64, and 5.97, respectively (P < 0.01). Incidences of sites requiring retreatment were similar in both groups, but the cost of treatment was 30% higher for teeth with RVDs. Grade C had the most significant influence on receiving retreatments (OR = 18.8, p = 0.005). CONCLUSION: Teeth with RVDs represent a risk indicator for tooth loss compared to identical contralateral teeth with similar PD in the same patient. Teeth with RVD had more risk of pocket opening during follow-up. CLINICAL RELEVANCE: While teeth with RVDs can be maintained long-term, they have twice the risk of pocket opening and tooth loss due to periodontitis during follow-up. Patients with systemic and local risk factors need to be monitored closely as they are at the highest risk of losing teeth with RVDs. The increased cost of retreatment for teeth with RVDs also has implications in terms of retention versus extraction and replacement.

Real-world efficacy of second-line therapies for Helicobacter pylori: a population-based study.

BACKGROUND: With the increasing prevalence of antibiotic resistance, real-world data on the optimal empirical second-line therapy for Helicobacter pylori are still limited. OBJECTIVES: To evaluate the real-world efficacy of various second-line therapies for H. pylori. PATIENTS AND METHODS: This was a retrospective population-based cohort study of all H. pylori-infected patients who had received the second-line treatment after the failure of primary clarithromycin triple therapy in Hong Kong between 2003 and 2018. The retreatment success rates of different second-line therapies were evaluated. RESULTS: A total of 7591 patients who received second-line treatment were included. Notably, the most commonly prescribed regimen was still clarithromycin triple therapy, but the frequency of use had decreased from 59.5% in 2003-06 to 28.7% in 2015-18. Concomitant non-bismuth quadruple therapy had emerged as the commonest regimen (from 3.3% to 43.9%). In a validation analysis, the sensitivity and specificity of retreatment-inferred second-line treatment failure were 88.3% and 97.1%, respectively. The overall success rate of second-line therapies was 73.6%. Bismuth quadruple therapy had the highest success rate of 85.6%, while clarithromycin triple therapy had the lowest success rate of 63.5%. Specifically, bismuth/metronidazole/tetracycline quadruple, metronidazole/tetracycline triple, levofloxacin/metronidazole/tetracycline quadruple, rifabutin/amoxicillin triple and amoxicillin/levofloxacin triple therapies had relatively higher success rates over 80%. Age, treatment duration, baseline conditions and first-line treatment used were associated with success rate. CONCLUSIONS: Bismuth quadruple therapy was the most effective second-line regimen for H. pylori in this real-world study. Despite a very low success rate, clarithromycin-containing triple therapies were still commonly used as second-line regimens.

Influence of sealer and supplementary approach on filling material removal during endodontic retreatment.

Both root canal sealer-based and supplementary protocols may influence removal of filling material during endodontic retreatment. Mesial root canals of extracted mandibular molars were prepared using HyFlex EDM 25/.08, and filled with a calcium silicate sealer (Bio-C Sealer), or an epoxy resin (AH Plus), using the single cone technique (n = 12). Retreatment was performed using ProDesign Logic (PDL) RT and PDL 35/.05. The specimens were randomly divided into two experimental groups (n = 12), and the sealers were distributed similarly. A supplementary protocol was performed with PDL 50/.01 or XP-endo Finisher. Root canal transportation and volume, in addition to the remaining filling material percentage were evaluated using high-resolution (5 µm voxel size) micro-CT. Statistical analysis was performed using t-tests (α = 0.05). Root canals filled with AH Plus presented high residual filling material (p < 0.05). Both protocols decreased residual volume of filling material in the apical third (p < 0.05). PDL 50/.01 increased the apical root canal volume (p < 0.05). No difference was observed between the systems regarding canal transportation (p > 0.05). In conclusion, AH Plus is more difficult to remove from the apical third than Bio-C Sealer. PDL 50/.01 and XP-endo Finisher enabled greater removal of filling materials in the apical third, in the retreatment of curved root canals, without promoting apical transport.

A 12-month randomized controlled trial to assess the efficacy of revitalization of retreated mature incisors with periapical radiolucency in adolescents.

The use of regenrative endodontics is restoring the health status of the root canals of retreated mature teeth is a novel approach. Therefore, the current trial aimed to compare the effectiveness of regenerative endodontic procedures (REPs) to non-surgical root canal retreatment (NS-RCR) in reducing periapical radiolucency over one year for the retreatment of mature incisors with periapical periodontitis. The secondary purpose was to assess clinical success and regain pulp sensibility. A parallel randomized controlled trial, 66 mature incisors with periapical radiolucencies were randomly divided into two equal groups and retreated with either REPs or NS-RCR. At baseline and after 6 and 12 months, teeth were assessed clinically and radiographically using a periapical index (PAI). The Mann-Whitney test was used to analyze nonparametric PAI scores. The Electric pulp test readings were analyzed using the repeated measure analysis of variance (ANOVA). Over the follow-up intervals, there was no significant intergroup difference in the PAI medians, the majority of the teeth displayed a reduction in periapical radiolucency. At the end of the follow-up period, the clinical successes for the REP and NS-RCR groups were 93.9% and 97%, respectively (p = 0.555). Positive pulp sensibility was recorded in 54.54% of cases in the REPs after 12 months. Both approaches showed a comparable diminishing of periapical radiolucencies and equivalent clinical results. A conventional, non-surgical endodontic retreatment may not always be necessary.

Lung squamous cell carcinoma responding to nivolumab retreatment six years after initial treatment: A case report.

A 61-year-old man presented to our hospital with a chief complaint of chronic cough. He was diagnosed with lung squamous cell carcinoma at clinical stage cT2aN3M1a. He received chemotherapy up to the fourth line, but both the primary tumor and lymph node metastases increased in size. Nivolumab, administered as the fifth line, resulted in a complete response (CR) that continued for 2 years and 8 months. Treatment was stopped due to the appearance of common terminology criteria for adverse events grade 1 pneumonitis. He was followed up without treatment for 3 years and 8 months, but a left supraclavicular fossa lymph node metastasis appeared. Retreatment with nivolumab was initiated, and the patient achieved CR again. One year and 6 months after retreatment, CR was maintained with nivolumab. This case represents a rare instance in which nivolumab yielded a significant response after a prolonged immune checkpoint inhibitor (ICI)-free interval. Our experience has shown that the long-term response to ICIs may deteriorate in the future. Therefore, retreatment with ICIs may be effective when the initial therapy is successful.

The ARH score, a practical guide to decision-making for retreatment with hepatic arterial infusion chemotherapy in hepatocellular carcinoma patients.

BACKGROUND: Hepatic arterial infusionchemotherapy (HAIC) is a promising option for large unresectable hepatocellular carcinoma (HCC). Identifying patients who could benefit from continuous HAIC remains a challenge. We aimed to establish an objective model to guide the decision for retreatment with HAIC. METHODS: Between 2015 and 2020, the data of patients with large unresectable HCC without macrovascular invasion or extrahepatic spread undergoing multiple HAIC cycles from 3 different centers were retrieved. We investigated the basic tumor parameters and the effect of HAIC on liver function and tumor response, and their impact on overall survival (OS). A point score (ARH, Assessment for Retreatment with HAIC) was built by using a stepwise Cox regression model in the training cohort (n = 112) and was validated in an independent validation cohort (n = 71). RESULTS: The high α-fetoprotein before the second cycle of HAIC, an increase in Child-Pugh score, and undesirable radiologic tumor responses remained independent negative prognostic factors and were used to create the ARH score. The prognosis of HCC patients deteriorated significantly with the increase in ARH score. The median OS of patients with ARH score 0-2 points and ≥ 2.5 points were 19.37 months and 11.60 months (P < 0.001). All of these results had been confirmed in the external validation cohort and demonstrated significance across multiple subgroups. CONCLUSIONS: The ARH score makes an excellent prediction of the prognosis of HCC patients who received retreatment of HAIC. Patients with an ARH score ≥ 2.5 prior to the second cycle of HAIC may not profit from further sessions.

Extrusion of debris during retreatment using various nickel-titanium files in teeth with simulated lateral root perforation.

PURPOSE: To investigate the influence of various nickel-titanium (Ni-Ti) files on debris extrusion during the retreatment of teeth with simulated lateral root perforation, focusing on root resorption. METHODS: Sixty human mandibular premolar teeth were divided into groups with and without perforation and further subdivided based on the retreatment technique. Lateral root perforations were created in one group (Group 1), while the other group had no perforations (Group 2). Two retreatment techniques were compared: Remover (RE)+One RECI (OR) and ProTaper Universal Retreatment (PTUR)+WaveOne Gold (WOG). The weight of the extruded debris was determined. The time of both retreatment procedures was measured. Statistical analyses were performed using a two-way analysis of variance (ANOVA) test (P < 0.05). RESULTS: Teeth with simulated lateral root perforation exhibited higher extrusion of debris during retreatment. In both groups, RE+OR files led to more extruded debris than PTUR+WOG files. However, this difference was statistically significant in Group 2 (P < 0.001). Compared to PTUR+WOG files, RE+OR files showed a statistically significant longer time to remove obturation material (P < 0.001). CONCLUSION: Perforated teeth exhibited significantly higher debris extrusion. While both file systems demonstrated similar debris extrusion in perforated teeth, the RE+OR files significantly increased debris extrusion in non-perforated teeth compared to the PTUR+WOG files.

Mirogabalin as a Therapeutic Option for Neuropathic Pain Emerging Post-endodontic Treatment: A Two-Case Report.

INTRODUCTION: Occlusal and percussion pain may manifest occasionally following endodontic treatment, influencing retreatment decisions. Two cases of periapical neuropathic pain, classified as post-traumatic trigeminal neuropathic pain according to the International Classification of Orofacial Pain, are presented. Although mirogabalin is effective in managing neuropathic pain, there is a lack of clinical reports on its use for occasional post-traumatic trigeminal neuropathic pain after endodontic treatment. These cases highlight clinical symptoms and successful treatment with mirogabalin for post-traumatic trigeminal neuropathic pain after endodontic treatment, providing clinicians a "take-away" lesson for improving patient condition. METHODS: The patients, referred by their primary dentist due to postendodontic abnormal pain, found no relief with antibiotics or nonsteroidal anti-inflammatory drugs. Although no findings including swelling or periapical radiolucency were observed around the tooth, they experienced occlusal and percussion pain. Local anesthetic testing showed that the pain originated from the peripheral area around the tooth rather than from central sensitization. Dental radiography and cone-beam computed tomography revealed no abnormal findings. Root canal retreatment was performed by a specialist in endodontic treatment. Although endodontic retreatment drastically decreased visual analog scale pain score, pain persisted. Based on the International Classification of Orofacial Pain criteria, diseases other than post-traumatic trigeminal neuropathic pain were excluded. Mirogabalin (10 mg/d) was prescribed once daily before bedtime. RESULTS: Visual analog scale scores gradually and drastically decreased 2 weeks after mirogabalin therapy. Several months later, no recurrence of postendodontic pain was observed after tapering off and discontinuing mirogabalin. CONCLUSIONS: These findings suggest the possibility of a new treatment method for post-traumatic trigeminal neuropathic pain after endodontic treatment.

Incidence of missed canals during endodontic treatment of maxillary first and second molars.

Untreated canals are a primary cause of persistent apical periodontitis, and the inability to identify and adequately treat canals has been considered a major cause of failure of root canal therapy in maxillary molars. The purpose of this retrospective study was to use cone beam computed tomography (CBCT) to quantify the number of missed canals in maxillary first and second molars needing endodontic retreatment after treatment by general dentists. A total of 401 CBCT scans of maxillary first and second molars were examined. A total of 214 scan sets (53.37% [95% CI, 48.48%-58.25%]) showed evidence of an untreated canal, with the highest rate (49.38%; n = 198) observed in the second mesiobuccal canal. Imaging revealed that multiple canals were missed in some patients, for a total of 225 missed canals. The examinations showed untreated first mesiobuccal canals in 2.99% of CBCT scan sets (n = 12), untreated distobuccal canals in 2.99% of CBCT scan sets (n = 12), and untreated palatal canals in 0.75% of CBCT scan sets (n = 3). Preoperative CBCT imaging should be considered prior to initial root canal treatment of maxillary molars. When the risks and limitations of CBCT are taken into consideration, the additional information it provides can improve diagnostic accuracy, increase confidence in decision-making, and positively impact treatment planning.

Giving the pulp another chance: a case report of vital pulp therapy retreatment.

Vital pulp therapy (VPT) has been increasingly advocated due to its advantages in preserving tooth vitality. While VPT is often successful, failures can occur, and traditional root canal therapy is often recommended following VPT failure. This case report provides an example of successful preservation of tooth vitality using coronal pulpotomy (CP), a more invasive type of VPT, after failure of partial pulpotomy (PP) that had been performed in a healthy 10-year-old boy. A mandibular right first molar with a diagnosis of reversible pulpitis was initially treated with PP, which included the use of tricalcium silicate cement as a pulp dressing and a resin-modified glass ionomer cement base, followed by placement of a composite resin restoration. The restoration dislodged after 34 months without complaints from the patient or radiographically detectable lesions. A stainless steel crown was placed on the tooth; however, 15 months after crown placement, the patient returned with symptoms in the treated tooth. The tooth was diagnosed with irreversible pulpitis and asymptomatic apical periodontitis but responded positively to cold testing, and the pulp appeared clinically vital upon direct inspection. The tooth was re-treated with CP, including the use of mineral trioxide aggregate as a dressing material, and examination 21 months posttreatment revealed successful resolution of the periapical lesion. When a tooth remains vital, a more invasive type of VPT may be an alternative to root canal therapy for treating failures in more conservatively treated teeth. Moreover, regular periodic recalls are essential for ensuring tooth survival and early detection of problems (ie, restoration failure) that may worsen treatment outcomes.

Outcomes-Based Treatment Planning in Endodontics: Applying the Latest Evidence.

A comprehensive understanding of the factors that influence treatment outcomes is crucial in endodontic diagnosis and treatment planning. Having knowledge that takes into account dental and patient-related conditions when choosing procedures can help clinicians maximize the prognosis of natural teeth and reduce postoperative complications. That being said, the landscape of outcome studies in endodontics is continually evolving, presenting a challenge for many clinicians trying to stay current with the latest literature. This article reviews factors that influence the outcomes of the following endodontic therapies: primary root canal treatment, nonsurgical retreatment, and surgical retreatment. An emphasis is placed on the importance of considering preoperative and treatment-related factors as prognostic indicators before developing a treatment plan, with the ultimate goal of enhancing tooth durability and ensuring patient satisfaction.

The incidence and intensity of postoperative pain and Flare-up following the use of three different intracanal medicaments in teeth with posttreatment apical periodontitis: a randomized clinical trial.

OBJECTIVES: This randomized clinical trial aimed to compare the effect of intracanal medicaments on the incidence of postoperative pain and flare-up with posttreatment apical periodontitis (PTAP) of retreatment cases. MATERIALS AND METHODS: One hundred twenty patients diagnosed with PTAP with single-rooted teeth with single-canal without spontaneous pain or swellings were included and randomly divided into three groups according to the intracanal medicament used. Intracanal medicaments were placed into the root canals following the removal of previous root canal fillings and re-instrumentation. Calcium hydroxide (Ca (OH)2), chlorhexidine gel (CHX), calcium hydroxide and chlorhexidine gel combinations were used as intracanal medicaments. Postoperative pain scores were recorded at 6 and 12 h and 1, 2, 3, 4, 5, 6, and 7 days using a visual analog scale (VAS). Sensitivity on percussion, spontaneous pain, swelling, antibiotic and analgesic requirements of the patients were evaluated during clinical examinations performed postoperatively after 2 and 7 days. RESULTS: There were no statistically significant differences between groups in terms of VAS scores following the intracanal medicament application (p > 0.05). However, compared to the patients of 20-34 and 50-65 age groups, greater VAS scores were observed in patients of 35-49 age groups at 12 h, and 3, 4, 7 days (p < 0.05). Flare-up was observed in only one patient in the CHX gel group, and no flare-up was observed in other groups. CONCLUSIONS: Similar postoperative pain incidence in all experimental groups indicates that all three medicaments are clinically acceptable in inter-appointment management of retreatment cases in terms of post-endodontic pain and flare-up. CLINICAL RELEVANCE: In this randomized clinical trial, three different intracanal medicaments were utilized in nonsurgical endodontic retreatment and their effect on postoperative pain and flare-up incidence was examined. Thus, this study will be a significant contribution in the decision-making during clinical practice; since there are a limited number of prospective clinical trials in the literature about the severity of pain following retreatment procedures including intracanal medicament use.

'Unusual' HCV genotype subtypes: origin, distribution, sensitivity to direct-acting antiviral drugs and behaviour on antiviral treatment and retreatment.

The high genetic diversity of hepatitis C virus (HCV) has led to the emergence of eight genotypes and a large number of subtypes in limited geographical areas. Currently approved pangenotypic DAA regimens have been designed and developed to be effective against the most common subtypes (1a, 1b, 2a, 2b, 2c, 3a, 4a, 5a and 6a). However, large populations living in Africa and Asia, or who have migrated from these regions to industrialised countries, are infected with 'unusual', non-epidemic HCV subtypes, including some that are inherently resistant to currently available direct-acting antiviral (DAA) drugs due to the presence of natural polymorphisms at resistance-associated substitution positions. In this review article, we describe the origin and subsequent global spread of HCV genotypes and subtypes, the current global distribution of common and unusual HCV subtypes, the polymorphisms naturally present in the genome sequences of unusual HCV subtypes that may confer inherently reduced susceptibility to DAA drugs and the available data on the response of unusual HCV subtypes to first-line HCV therapy and retreatment. We conclude that the problem of unusual HCV subtypes that are inherently resistant to DAAs and its threat to the global efforts to eliminate viral hepatitis are largely underestimated and warrant vigorous action.