Forms of Roots and Root Canals in Endodontic Therapy

Tooth crown to root development has been extensively studied from the viewpoint of both anatomy and embryology. However, development of the root canal system has received little attention. Studies using extracted teeth have revealed the proportions of teeth showing variations in their roots and root canals, the locations of the lateral canal, and the numbers of apical foramina, etc. In addition, endodontists have been able to obtain information on teeth from dental X-ray films before the start of root canal treatment. Endodontic therapy involves a degree of difficulty because the root canal cannot be observed directly from the outside. Therefore, detailed information about the root canal system is important for endodontic treatment. Recently, root canal treatment using microscopy has been undertaken. Microscopic images obtained under illumination facilitate easy and precise root canal treatment, and reveal structural abnormalities. However, endodontists, anatomists, and embryologists need to understand the complex development of the root canal system in order to facilitate accurate endodontic therapy, thus contributing to the health of patients.     

Identification of Culturable and Nonculturable Microorganisms,Lipopolysaccharides, and Lipoteichoic Acids From Root Canals of Teeth With Endodontic Failure

AimTo elucidate the presence of apical periodontitis in the root canal of teeth with secondary/persistent infection, including composition of microbiota, levels of endotoxins and lipoteichoic acid (LTA), and clinical implications of these findings.MethodSamples were collected from root canals of 50 patients who needed endodontic retreatment and had radiographic evidence of apical periodontitis. Microorganisms were identified by using the culture technique and biochemical tests. Nested–polymerase chain reaction (nested-PCR) was used to identify 17 species of specific bacteria. Lipopolysaccharides (LPS) and LTAs were quantified by using, respectively, limulus amebocyte lysate and enzyme-linked immunosorbent assay tests.ResultsBacteria were detected in all samples by culture and molecular methods. A total of 154 gram-positive strains, of 188 strains isolated, were found in the root canals by culture. Enterococcus faecalis and Gemella morbillorum were the most prevalent species identified by the biochemical tests, whereas molecular analyses (nested-PCR) showed a high frequency of P. gingivalis, E. faecalis, and Fusobacterium nucleatum. LPS and LTA were detected in all samples, with mean values being 3.52 EU/mL and 597.83 pg/mL, respectively. Significant statistical correlations were found between levels of LTA and clinical features.ConclusionDespite the prevalence of gram-positives, the microbiota present in secondary/persistent infections showed a large variety of species. Within this diversity, associations were found between specific bacteria and clinical features. In addition, higher levels of LTA were statistically associated with larger periapical radiolucent areas, but no correlation between this feature and LPS was found.     

热软化牙胶插入充填法磨牙多根管充填的临床研究

目的　分析热软化牙胶插入法充填磨牙多根管的方法和其特点。方法　选择门诊磨牙尖周炎和牙髓炎患者 5 8例 ,随机分成 2组 :对照组采用牙胶侧方加压法充填 ,实验组采用热软化牙胶插入法充填。摄X线牙片比较两组根管充填效果及充填操作时间。结果　经秩和检验 ,侧方加压法组和热软化牙胶插入法组在充填弯曲根管时 ,两者充填效果总体分布有差异 ,热软化牙胶插入法充填弯曲根管效果优于侧方加压法 (U =4 4 0 1,P <0 0 1) ;而两组在较直根管充填效果差异无统计学意义 (P >0 5 ) ,两组的充填时间经t检验统计差异有显著性。结论　热软化牙胶插入法较传统牙胶侧方加压法对根管三维具有更好的适应性 ,尤其适合于弯曲根管的充填 ,操作简捷、省时。     

Shaping Ability of Three Nickel-Titanium Endodontic File Systems in Simulated S-shaped Root Canals

Introduction

The purpose of this study was to determine the shaping ability of 3 nickel-titanium (NiTi) endodontic file systems by measuring canal transportation.

Methods

Seventy-two S-shaped canals in resin blocks were randomly allocated into 3 groups (n = 24): the Self-Adjusting File (SAF; ReDent Nova, Ra’anana, Israel) group, the Typhoon group (Typhoon rotary files with Controlled Memory Wire; DS Dental, Johnson City, TN), and the Vortex group (ProFile Vortex rotary files with M-Wire NiTi; Dentsply Tulsa Dental Specialties, Tulsa, OK). Blocks were secured in a jig for imaging standardization and instrumentation stabilization. Gates Glidden and PathFile drills (25 mm/.02 taper) were used to prepare the glide paths. For the Typhoon and Vortex groups (25 mm/.04 taper), canals were flooded with sterile water and instrumented using a crown-down technique from sizes 40 to 20/.04 and then apically enlarged to size 30/.04. The SAF group (25 mm) was instrumented with constant sterile water irrigation in a light-pecking, transline motion. Pre- and postinstrumentation images were taken at 40× magnification and layered, and canal transportation was measured.

Results

After adjusting for the level and canal wall side, the mean transportation was significantly higher for the Typhoon (P < .001) and Vortex (P = .005) groups compared with the SAF group. Additionally, the mean transportation was significantly higher for the Typhoon group versus the Vortex group (P < .001).

Conclusions

Under the conditions of this study, SAFs showed less canal transportation than ProFile Vortex and Typhoon files in simulated S-shaped root canals.     

Regenerative Endodontic Procedures for Traumatized Immature Permanent Teeth with Severe External Root Resorption and Root Perforation

External root resorption (ERR) is often a complication of traumatic injury to the teeth. Traditionally, external inflammatory root resorption is treated with calcium hydroxide. The outcome of ERR, especially replacement resorption, is unpredictable. The purpose of the present case report was to describe regenerative endodontic procedures (REPs) for 1 replanted avulsed tooth with severe external root resorption and root perforation (tooth #9) and 1 extruded tooth (tooth #8). A 9-year-old girl was referred for the treatment of teeth #8 and #9 4 months after the initial trauma. Clinical examination showed that tooth #9 had a sinus tract present near the periapical area, was tender to percussion and palpation, and did not respond to pulp sensibility tests. Tooth #8 responded to pulp sensibility tests. Periapical radiographic and cone-beam computed tomographic examination showed that tooth #9 had a periapical radiolucent lesion and severe ERRs with a root perforation. Tooth #9 was diagnosed with a necrotic pulp and symptomatic apical periodontitis. Regenerative endodontic procedures (REPs) were initiated. Tooth #8 became nonresponsive to pulp sensibility tests and developed a periapical lesion 12 months after REPs of tooth #9 and was also treated with REPs. The clinical symptoms and apical lesions resolved for both teeth after REPs. The severe ERRs were arrested, and root perforation was repaired for tooth #9. Teeth #8 and #9 underwent canal obliteration by hard tissue formation after REPs and were in function at 18 months and 30 months, respectively. REPs may be used to manage traumatized immature permanent teeth with a necrotic pulp and apical periodontitis associated with severe ERR and root perforation.     

Regenerative Endodontic Treatment for Necrotic Immature Permanent Teeth

This retrospective study included 23 necrotic immature permanent teeth treated for either short-term (treatment period <3 months) or long-term (treatment period >3 months) using conservative endodontic procedures with 2.5% NaOCl irrigations without instrumentation but with Ca(OH)₂ paste medication. For seven teeth treated short-term, the gutta-percha points were filled onto an artificial barrier of mineral trioxide aggregate (MTA). For 16 teeth treated long-term, the gutta-percha points, amalgam, or MTA were filled onto the Ca(OH)₂-induced hard tissue barrier in the root canal. We found that all apical lesions showed complete regression in 3 to 21 (mean, 8) months after initial treatment. All necrotic immature permanent teeth achieved a nearly normal root development 10 to 29 (mean, 16) months after initial treatment. We conclude that immature permanent teeth with pulp necrosis and apical pathosis can still achieve continued root development after proper short-term or long-term regenerative endodontic treatment procedures.     

Factors Related to the Outcomes of Cracked Teeth after Endodontic Treatment

IntroductionCracked teeth are a common clinical finding; however, their presence renders diagnosis and prognosis unreliable. The purpose of this research was to assess the correlations of multiple factors on the prognosis of cracked teeth that had undergone endodontic treatment.MethodsA total of 3680 patients who received endodontic treatment by an advanced postdoctoral education program in endodontics with follow-up records of at least 1 year were assessed. From this sample, 62 patients met the inclusion criteria and were included in the final analysis. The factors being evaluated included demographics, clinical symptoms and signs, radiographic findings, and restoration type. Statistical analysis was then completed using the chi-square and Fisher exact tests.ResultsThe mean follow-up period was 23.3 months, with an overall tooth success rate of 75.8%. The success rates differed significantly when the patient had an existing preoperative periapical lesion, lacked a proper permanent restoration on the treated tooth, or had a post placed after root canal treatment. Data analysis showed that restoring the tooth after endodontic treatment was the single most important factor for prognosis. In fact, the endodontically treated teeth with definitive full-coverage restorations had a 2-year success rate of 93.6%.ConclusionFull-coverage restorations should be considered an important part of the treatment plan for cracked teeth treated endodontically.     

PROMs Following Root Canal Treatment and Surgical Endodontic Treatment

The FDI is currently working on developing a tool to encompass patient-reported outcome measures (PROMs) within the overall assessment of outcomes of endodontic treatment. The outcome of endodontic treatment has traditionally been determined by various clinical and radiographic criteria. However, these parameters do not address the impact of treatment on a patient's oral health–related quality of life (OHRQoL). OHRQoL, a crucial PROM, can be used to understand treatment outcome from a patient-centred perspective, thus improving clinician–patient communication whilst guiding decision-making. This focussed review aims to recount the OHRQoL of patients following nonsurgical root canal treatment and surgical endodontic treatment, with a specific focus on the minimal important difference (MID; the minimum score changes of an outcome instrument for a patient to register a clinically significant change in their OHRQoL and/or oral condition) and the methods used to determine it. The current evidence indicates that the OHRQoL of patients requiring root canal treatment is poorer than those without such need. Accordingly, the literature suggests that OHRQoL improves following nonsurgical or surgical endodontic treatment. However, study methodologies vary widely, and conclusions cannot be drawn with high confidence, nor can MID recommendations be provided. Well-designed clinical studies with baseline measurements and appropriate follow-up time frames are therefore needed. Despite that the literature is rife with outcome studies, research on PROMs is an area that deserves greater attention, particularly in relation to the MID. Determining the MID will facilitate the understanding of changes in outcome scores from the patients’ perspective, thus allowing for more informed decision-making in clinical practice.     

ProTaper和ProTaper Universal机用镍钛器械在模拟根管内成形能力的研究

目的：利用树脂模拟根管比较机用ProTaper和ProTaper Universal在弯曲根管内的成形能力。方法：使用机用ProTaper和ProTaper Universal预备两组模拟树脂根管,记录预备时间、树脂切割量、外形改变等,并对预备前后模拟根管形态改变、弯曲内外侧去除树脂量的多少进行分析和比较。结果：两组器械在预备时间上、器械变形方面无显著性差异,但预备后根管中下段均有部分偏移。ProTaper Universal F1、F2在弯曲内侧切割的树脂量多于ProTaper,而F3的树脂切割量少于ProTaper F3。结论：两组器械均能较好地完成根管预备,但是在预备根管中下段时,都会造成一定程度上的偏移。     

不同功率Diode激光用于乳牙根管清洁的体外研究

目的: 评价不同功率Diode激光(810 nm)对乳牙根管壁玷污层的清除效果。方法: 选取66颗因滞留拔除的乳前牙,随机分为:阴性对照组(未处理,n=6)、阳性对照组(5.25%次氯酸钠冲洗, n=6)和实验组(Diode激光照射,n=54);实验组按不同激光功率分为0.1 W、0.5 W、1.0 W、1.5 W、2.0 W、2.5 W、3.0 W、3.5 W和4.0 W组(n=6)。将光纤头插入根管至工作长度后照射,扫描电子显微镜(SEM)观察根管内壁清洁效果。结果: SEM下可见根管上段、中段和下段分别在1.0W、1.5W和2.0W时有明显的清洁效果,优于与之相邻低功率组和阳性对照组(P<0.05),与高于此功率组相比无显著差异;功率在3.0 W时,根管管壁开始出现牙本质熔融。结论: Diode激光可有效清除乳牙根管玷污层,其有效功率范围为1.0~2.5 W,最佳功率为2.0 W。     

Maxillary Molars With Morphologic Variations of the Palatal Root Canals: A Report of Four Cases

IntroductionThe purpose of this article was to show the importance of the knowledge of the anatomy of root canals. Unusual root and root canal morphologies associated with both buccal roots of upper molars have been recorded in several studies in the literature. However, scientific information focusing on variations of the palatal root is rare.MethodsIn this report, four cases are presented involving the root canal treatment of maxillary first and second molars with unusual morphologic configurations of the palatal root canals.ResultsDuring root canal treatment, type IV and V configurations as defined by Vertucci of the palatal canals of two first and two second maxillary molars were identified. After mechanical instrumentation, the canals were obturated. Radiologic and clinical re-evaluation showed no signs of inflammation.ConclusionsThis report describes and discusses the possibility of different root and canal variations of the maxillary molars from a clinical point of view. Anatomic variations can occur in any tooth, and palatal roots of maxillary first and second molars are no exception. Therefore, careful examination of radiographs and internal anatomy of teeth is essential.     

Survival Rates of Teeth with Primary Endodontic Treatment after Core/Post and Crown Placement

Introduction

The objective of this study was to determine the effect of delayed placement of the core/post and crown on the outcomes of nonsurgical root canal therapy (NSRCT).

Syringe Irrigation in Minimally Shaped Root Canals Using 3 Endodontic Needles: A Computational Fluid Dynamics Study

IntroductionThe aim of this study was to compare the irrigant flow in curved root canals prepared to various apical sizes by constant-taper or variable-taper instruments during syringe irrigation with 3 endodontic needles at 2 different flow rates.MethodsTwo matched curved mesial root canals of human mandibular molars were imaged by micro–computed tomographic imaging after preparation to apical size 20, 25, and 30/.06 taper either by constant-taper or variable-taper instruments. A Computational Fluid Dynamics model was used to simulate the irrigant flow in the 2 root canals prepared to each apical size during syringe irrigation with a 30-G open-ended needle and 30-G and 31-G closed-ended needles at 0.05 and 0.15 mL/s.ResultsThe irrigant could not penetrate up to the working length in root canals prepared to apical size 20 or 25/.06 taper. The 30-G open-ended needle combined with the low flow rate allowed the irrigant to reach the working length in size 30/.06 taper root canals while maintaining a relatively low apical pressure, but the wall shear stress was very low. The 31-G closed-ended needle combined with the high flow rate also delivered the irrigant to the working length in size 30 root canals and developed higher wall shear stress, but the apical pressure was also higher.ConclusionsSyringe irrigation using 30-G and 31-G needles was compromised in minimally shaped root canals.     

A Standardized Novel Method to Measure Radiographic Root Changes after Endodontic Therapy in Immature Teeth

Introduction

Outcome studies of endodontic treatment of necrotic immature permanent teeth rely on radiographic measures as surrogates of whether the treatment achieved regeneration/revascularization/revitalization. An increase in radiographic root length and/or width is thought to result in a better long-term prognosis for the tooth. In this study, a method to measure radiographic outcomes of endodontic therapies on immature teeth was developed and validated.

Methods

A standardized protocol was developed for measuring the entire area of the root of immature teeth. The radiographic root area (RRA) measurement accounts for the entire surface area of the root as observed on a periapical radiograph. Reviewers were given instructions on how to measure RRA, and they completed measurements on a set of standardized radiographs.

Results

The intraclass correlation between the 4 reviewers was 0.9945, suggesting a high concordance among reviewers. There was no effect of the reviewer on the measured RRA values. High concordance was also observed when 1 rater repeated the measurements, with an intraclass correlation value of 0.9995. There was no significant difference in RRA values measured at the 2 sessions by the same rater. Furthermore, significant differences in RRA were detectable between clinical cases that showed obvious continued root development and cases that did not demonstrate discernible root development.

Conclusions

These results suggest that RRA is a valid measure to assess radiographic outcomes in endodontically treated immature teeth, and RRA should be useful in future clinical studies of regenerative endodontic outcomes.     

12-month Success of Cracked Teeth Treated with Orthograde Root Canal Treatment

Introduction

Long-term studies examining the treatment outcomes of “cracked teeth” that received orthograde root canal treatment in the United States do not exist. The purpose of the present study was to examine the distribution and 1-year treatment outcomes of cracked teeth receiving orthograde root canal treatment in 1 private endodontic practice over a 25-year period.

Guided Endodontic Access of Calcified Anterior Teeth

Pulp canal calcification is characterized by the deposition of calcified tissue along the canal walls. As a result, the root canal space can become partially or completely obliterated. Recently, “guided endodontics” has been reported as an alternative solution in cases of partial or completed canal obliteration. Although this technique can enhance minimally invasive access to the calcified canal, it has been shown that the incisal surfaces are often removed during the access of anterior teeth. This report describes 2 cases of guided endodontics using conventional palatal access in calcified anterior teeth and discusses the applicability of this approach in cases of pulp canal calcification with apical periodontitis and acute symptoms. The method demonstrated high reliability and permitted proper root canal disinfection expeditiously, without the unnecessary removal of enamel and dentin in the incisal surface.     

Evaluating Two Techniques on Removal of Fractured Rotary Nickel-Titanium Endodontic Instruments from Root Canals: An In Vitro Study

This study evaluated the ultrasonic technique (US) and instrument removal system (iRS) in removing fractured rotary nickel-titanium (NiTi) from root canals. A total of 30 extracted human molars with closed apices were collected. Profile .06 taper rotary endodontic instruments (Dentsply Maillefer, Ballaigues, Switzerland) 25-mm long and ISO size 25 were driven into the mesial canal to be fractured in the curve. Angles and radii of curvature were measured for all the canals with the fractured fragments, and then canals were classified into slight, moderate, and severe subgroups according to their curvature angles. Within each subgroup, teeth were randomly distributed into US or iRS according to measured angles and radii; a total of 15 canals were assigned to both US and iRS techniques. The overall success rate was 70% (n = 21). Less curved canals and longer radii of curvature showed more success. The median time used for retrieval was 40 minutes using the US technique, whereas it was 55 minutes for iRS. The removal of fractured rotary NiTi endodontic instruments was more successful with less curved canals and longer radius of curvature above 4.4 mm.