Preparation Of Root Canal System Research Articles

Effects of different root canal preparation techniques on premolars endodontic interappointment pain

Objective To study the clinical effects of different methods on endodontic inter appointment pain(EIAP) happened to the patients after premolar root canal preparations. Methods 152 teeth from 134 patients with acute or chronic pulpitis or apical periodontitis were randomly divided into T group and K group, used TiLos mixed root canal preparation system with step-down technique and stainless steel K file with step-back technique respectively to prepare root canal.Afterwards, the incidence rates of EIAP were observed and recorded. Results The incidence rates of EIAP in T group and K group were 6.17% and 21.11%, respectively.There was statistically significant difference between the two groups (χ2=7.404, P<0.01). Conclusion TiLos mixed root canal preparation system with step-down technique to prepare root cancal can reduce the incidence rate of EIAP. Key words: Root canal preparation; Toothache; TiLos mixed root canal preparation system; Step-down technique; Step-back technique; Premolar

Success Rate of Root Canal Treatment by Conventional Root Canal Therapy Without Using Intracanal Medicament in Infected Canals

Background: Root canal system, when becomes infected is managed by thorough debridement and specific shaping of the root canal. It is to be followed by a specific type of filling. The ultimate goal of these approaches is to create an environment in which the body’s immune system can produce healing of the apical periodontal attachment apparatus. Thorough debridement and shaping are carried out usually by biomechanical preparation of root canal system along with intracranial medicament. The use of intracanal medicaments is still debatable. This study was designed to evaluate the usefulness of root canal treatment without using any biomedical preparation.Methods: The study was carried out in the Department of Conservative Dentistry and Endodontics, BSMMU, Dhaka July 2003 to July 2004. In the present study, 36 cases of endodontically involved infected teeth were treated by conventional root canal treatment without using intracanal medicaments and patients were followed up at 6 and 12 months after root canal treatment.Results: At 6 and 12 months follow up, an overall treatment success was revealed in clinical and radiological findings.Conclusion: It is the biomechanical preparation of the canal which decides the success rate of root canal treatment of infected teeth, not the use or nonuse of intracanal medicament.Birdem Med J 2017; 7(3): 221-223

Prevention of Ni Ti Instrument Fracture: A Systematic Review

A successful root canal treatment depend upon so many factor but the most important factor which determine the efficacy of all subsequent procedures such as debridement ,medicament delivery, and obturation is mechanical preparation of root canal system .Traditionally stainless steel files were used, but with the introduction of nickel titanium (NiTi) alloys significantly broadened the instrument design. So many factors affect the separation of nickel titanium instrument and the rate of separation of nickel titanium is 30-60% and breakage rate 9.4%. The aim of this review article is to discuss the methods that prevent the separation of nickel titanium instrument and improve the success of root canal treatment to save teeth.

Light-emitting Diode Assessment of Dentinal Defects after Root Canal Preparation with Profile, TRUShape, and WaveOne Gold Systems

IntroductionThe objective of this study was to use light-emitting diode (LED) transillumination to assess the presence of dentinal defects in roots instrumented with 3 different root canal preparation systems: ProFile (Dentsply Tulsa Dental Specialties, Tulsa, OK), TRUShape (Dentsply Tulsa Dental Specialties), and WaveOne Gold (Dentsply Tulsa Dental Specialties). MethodsEighty mesial roots of mandibular molars presenting 2 canals were randomly divided into 4 different groups (n = 20) as follows: the control group, no root canal preparation was performed; the ProFile group, root canals were prepared with nickel-titanium ProFile sizes 20.06 and 25.06; the TRUShape group, root canals were prepared with nickel-titanium rotary TRUShape instrument sizes 20.06 and 25.06; and the WaveOne Gold group, root canals were prepared with the reciprocating WaveOne Gold instrument #25.07. The specimens were sliced at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling. Microscopic pictures of the specimens were taken with the aid of LED; the root canal space was masked, and 2 independent evaluators assessed the images for the assessment of dentinal defects. The number of dentinal defects was recorded, and the chi-square test was used for statistical analysis (P < .05). ResultsThe number of specimens presenting dentinal defects was as follows: the control group = 10, the ProFile group = 10, the TRUShape group = 13, and the WaveOne Gold group = 10. ConclusionsUsing the novel LED method, no difference in the visualization of dentinal defects was found among the ProFile, TRUShape, and WaveOne systems and the control group. Previous studies using the traditional sectioning method lack proper control and should be evaluated with caution.

Reciproc vs. hand instrumentation in dental practice: a study in routine care.

Background. Little is known about the clinical impact of new root canal preparation systems in general dental practice under routine care conditions. Therefore, we compared hand instrumentation (H) with Reciproc (R) (VDW, Munich, Germany) preparation. The outcomes were endodontic related pain and oral health related quality of life (OHRQoL), evaluation of the procedures by the patients and the strain felt by the dentists during root canal therapy.Methods. Six dentists participated in the trial as practitioner–investigators. In the first phase of the trial they prepared root canals with H and in the second phase with R. The patients documented their pain felt with a visual analogue scale (VAS 100) and OHRQoL with the German short version of the oral health impact profile (OHIP-G-14) before treatment and before the completion of therapy and answered questions about how they experienced the treatment. The dentists documented their physical strain during treatment.Results. A total of 137 patients were included in the evaluation. 66 patients were treated with H, 71 with R. Pain reduction was 32.6 (SD 32.9) VAS (H) vs. 29.4 (SD 26.9) VAS (R) (p = 0.550), and the improvement of the OHIP-14 score was 5.5 (SD 9.2) (H) vs. 6.7 (SD 7.4) (R) (p = 0.383). There were no statistical differences in both groups. Significantly fewer patients felt stressed by the duration of treatment with R as with H (p = 0.018). Significantly more dentists reported that their general physical strain and the strain on their fingers were less severe with R than with H (p = 0.013 and p < 0.001).Discussion. H as well as R effectively reduced endodontic related pain and OHRQoL without statistical differences. R has advantages in terms of how patients experience the treatment and regarding the physical strain felt by the dentists.

Comparison of Dentinal Crack Formation With Reciproc, Mtwo and ProTaper Root Canal Preparation Systems

Background: Instrumentation with rotary instruments could potentially cause dentinal cracks possibly leading to tooth fracture. Reciproc files require a single file to finalize the root canal preparation and the effect of this procedure has not been compared with other systems. Objectives: The aim of this study was to compare the incidence of dentinal micro-cracks following root canal preparations with ProTaper, Mtwo and Reciproc files. Materials and Methods: In an experimental in vitro trial, 80 maxillary and mandibular first molars were selected and their crowns and distal roots were cut. The roots were then examined to remove any previous cracks and defects. An impression polyether material was used to simulate teeth periodontal ligament (PDL). The teeth were divided to four experimental groups (n = 20) and prepared using Reciproc, Mtwo and ProTaper or remained unprepared as a control group. The specimens were then sectioned horizontally on 3, 5 and 9 mm from the apex and number of micro-cracks was determined by stereomicroscope. The incidence of dentinal cracks on different systems or sections were statistically analyzed by means of the chi-square test. Results: Dentinal defects on 3-mm, 5-mm and 9-mm sections from the apex were noted in 10 (5.6%); 7 (3.9%) and 9 (5.0%) samples of all, respectively. Following canal preparation using Reciproc, ProTaper and Mtwo systems, the defects were observed in 7 (3.9%), 12 (6.7%) and 7 (3.9%) the sections, respectively. No significant differences were observed regarding the defect incidence on the studied instrumentation files or sections. Conclusions: Regarding the study limitations, dentinal cracks were observed in all files and distances from the apex. Although there was more crack incidence in ProTaper files, no significant differences were noted regarding the studied systems and sections from the apex.

Management of Independent Middle Mesial Canal in Mandibular First Molar Using Cone Beam Computed Tomography Imaging as an Adjunct - A Case Report

The primary objective of root canal therapy is adequate biomechanical preparation of root canal system followed by 3D obturation.in clinics we are encountered with several anatomical variations, which we need to manage efficiently. One of the major factors responsible for failure of root canal therapy is missed canals. Recent technological advances have given the clinician opportunity to identify anatomical variations and treat them to satisfaction.

Comparative Analysis of Crack Propagation in Roots with Hand and Rotary Instrumentation of the Root Canal -An Ex-vivo Study.

Success of any endodontic treatment depends on strict adherence to 'endodontic triad'. Preparation of root canal system is recognized as being one of the most important stages in root canal treatment. At times, we inevitably end up damaging root dentin which becomes a Gateway for infections like perforation, zipping, dentinal cracks and minute intricate fractures or even vertical root fractures, thereby resulting in failure of treatment. Several factors may be responsible for the formation of dentinal cracks like high concentration of sodium hypochlorite, compaction methods and various canal shaping methods. To compare and evaluate the effects of root canal preparation techniques and instrumentation length on the development of apical root cracks. Seventy extracted premolars with straight roots were mounted on resin blocks with simulated periodontal ligaments, exposing 1-2 mm of the apex followed by sectioning of 1mm of root tip for better visualization under stereomicroscope. The teeth were divided into seven groups of 10 teeth each - a control group and six experimental groups. Subgroup A & B were instrumented with: Stainless Steel hand files (SS) up to Root Canal Length (RCL) & (RCL -1 mm) respectively; sub group C & D were instrumented using ProTaper Universal (PTU) up to RCL and (RCL -1mm) respectively; subgroup E & F were instrumented using ProTaper Next (PTN) up to RCL & (RCL -1 mm) respectively. Stereomicroscopic images of the instrumentation sequence were compared for each tooth. The data was analyzed statistically using descriptive analysis by 'Phi' and 'Cramers' test to find out statistical significance between the groups. The level of significance was set at p< 0.05 using SPSS software. Stainless steel hand file group showed most cracks followed by ProTaper Universal & ProTaper Next though statistically not significant. Samples instrumented up to 1mm short of working length (RCL-1mm) showed lesser number of cracks. All groups showed cracks formation, the stainless steel group being the highest. Working 1mm short of apex reduces the incidence of crack formation.

Effect of different irrigating protocols on push out bond strength of Resilon/Epiphany obturation system

PurposeTo evaluate the effect of different root canal irrigating regimens on the push-out bond strength of RealSeal root canal obturation system. Materials and methods16 mm ± 1 of roots of 70 freshly extracted single rooted human teeth were obtained and divided randomly into seven groups (n = 10) according to irrigation regimens throughout root canal preparation and final rinse: 1(DW–DW), 2(NaOCl–NaOCl), 3(NaOCl–MTAD), 4(NaOCl–EDTA), 5(CHX–CHX), 6(CHX–MTAD), 7(CHX–EDTA). All root canals of all groups were prepared using K3 root canal preparation system up to size #40/0.06 taper and filled using RealSeal Root canal obturation system. Two-millimeter thick horizontal sections from the coronal, middle and apical thirds of each root were sliced for the push-out bond strength measurement. ResultsIn cervical sections the highest push-out bond strength value was recorded for NaOCl–MTAD (4.074 ± 2.524) followed by CHX–MTAD (3.795 ± 1.935), CHX–EDTA (2.659 ± 0.587), NaOCl–EDTA (2.404 ± 1.166), CHX–CHX (1.905 ± 0.573), NaOCl–NaOCl (1.690 ± 0.427) and the least value was recorded for DW–DW (0.791 ± 0.381) with statistical significant difference between groups (P < 0.001). In middle sections the highest value was recorded for CHX–MTAD (3.801 ± 0.186) followed by CHXEDTA (3.222 ± 0.148), NaOCl–MTAD (3.119 ± 0.306), NaOCl–EDTA (2.066 ± 0.805), CHX–CHX (1.624 ± 0.724), NaOCl–NaOCl (1.350 ± 0.539) while the lowest value was recorded for DW–DW (0.684 ± 0.382) with no statistical significant difference among groups (P = 0.067). In apical sections the highest value was recorded for groups NaOCl–MTAD (2.654 ± 0.733), CHX–MTAD (2.020 ± 1.5522), CHX–EDTA (1.878 ± 0.808), NaOCl–EDTA (1.763 ± 0.068), NaOCl–NaOCl (1.260 ± 0.846), CHX–CHX (1.175 ± 0.298) and the lowest value was recorded for DW–DW (0.631 ± 0.152) with statistical significant difference between groups (P = 0.006). ConclusionWhenever root canal obturation using RealSeal is decided, it is preferred to use NaOCl solution throughout instrumentation in association with MTAD as a final irrigant after instrumentation to obtain a the highest push-out bond strength to root canal dentin specially at the coronal sections that showed higher bond strength than middle and apical sections.

Evaluation of Apically Extruded Bacteria Associated with Different Nickel-Titanium Systems

IntroductionThe aim of this in vitro study was to evaluate the amount of apically extruded bacteria associated with several root canal preparation systems. MethodsForty-four extracted human mandibular premolar root canals were contaminated with an Enterococcus faecalis suspension. After incubation at 37°C for 24 hours, the root canals were instrumented using the Twisted File (SybronEndo, Orange, CA), OneShape (Micro Mega, Besançon, France), and ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland). During instrumentation, apically extruded bacteria were collected into vials containing 0.9% NaCl. The microbiological samples were taken from the vials and incubated in brain-heart agar medium for 24 hours. The numbers of colony-forming units were determined. The data obtained were analyzed using Welch analysis of variance followed by post hoc Games-Howell tests. ResultsProTaper Next extruded the highest amount of bacteria, whereas OneShape extruded the least compared with all the other instruments (P = .004). There was a significant difference between OneShape and ProTaper Next in the number of colony-forming units (P = .007) but not between OneShape and Twisted File (P > .05). ConclusionsAll instrumentation systems extruded bacteria beyond the foramen. The OneShape system extruded less bacteria compared with the Twisted File and ProTaper Next systems.

Influence of Exposing Root Canal Dentin to Calcium Hydroxide on Its Flexural Strength

Calcium hydroxide has been used extensively in endodontic treatments, for instance as an intra-canal dressing; however, the exposure of root canal dentin to calcium hydroxide may affect its flexural strength and could have important clinical implications for endodontic treatment. The purpose of this in vitro study was to investigate the influence of calcium hydroxide on the flexural strength of root canal dentin.Seventy-two extracted single-rooted human mandibular premolars were used in this study. Each tooth was instrumented using crown-down technique and was irrigated using sterile saline. The teeth were assigned into three groups of 24 each. The prepared root canal system of each tooth was filled with calcium hydroxide mixed with sterile saline (group 1), a calcium hydroxide commercially available product (UltraCal®) (group 2) or saline solution (group 3, as control). The apices and access opening were sealed using composite resin, and the teeth were immersed in artificial saliva. After 7, 14 and 30 days of immersion, the inner root canal dentin of 8 teeth respectively from each group were sectioned to create dentin bars (1 X 1 mm, with 7 mm in length). Each dentin bar then was subjected to a three-point bending flexural test using MTS (Universal Testing Machine). Data gathered were then analyzed using two-way ANOVA, followed by Tukey’s test with the level of significance of 95%. The results showed that exposure to calcium hydroxide either using calcium hydroxide mixed with sterile saline or UltraCal® for 14 and 30 days can reduce flexural strength of root canal dentin compared to control group (p&lt;0.05). In contrast, after 7 days exposure, there was no significantly different of flexural strength between three groups (p&gt;0.05). It can be concluded that calcium hydroxide reduced the flexural strength of root canal dentin. The longer the exposure to calcium hydroxide would produce a greater effect on flexural strength of root canal dentin.

Evaluation of apically extruded debris associated with several Ni-Ti systems.

To evaluate the apical extrusion of debris associated with several root canal preparation systems in vitro. Forty-five extracted human mandibular premolars with single canals and similar lengths were used. The root canals were instrumented using ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), Twisted File (SybronEndo, Orange, CA, USA) or WaveOne (Dentsply Maillefer, Ballaigues, Switzerland). Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The Eppendorf tubes were then stored in an incubator at 70 °C for 5 days. The Eppendorf tubes were weighed to obtain the final weight of the Eppendorf tubes plus extruded debris. Three consecutive weights were obtained for each tube. The groups were compared using the Kruskal-Wallis one-way analysis of variance on Ranks and Tukey's test. The ProTaper Next group produced the highest mean extrusion value whilst WaveOne produced less debris compared with all the other instruments (P > 0.05). There was a significant difference between the ProTaper Next and WaveOne group (P < 0.05). Apically extruded debris was associated with all instrumentation techniques. The WaveOne system extruded less debris compared with the Twisted File and ProTaper Next.

Cleaning efficacy of different root canal preparation systems and irrigation regimens

PurposeTo compare the cleaning efficacy of root canal walls after using two Nickel–Titanium (Ni–Ti) rotary files (Flexmaster and Mtwo) and one hand Ni–Ti file (Ni–Ti flex-K) when associated with different final irrigation regimens (SmearClear, 17% ethylene diamine tetra acetic acid (EDTA) and sodium hypochlorite). Materials and methodsNinety extracted human premolars with similar range of canal curvature (21–39°) were selected. After crown removal and working length determination, roots were divided into three equal groups according to root canal instrumentation: Group I and Group II were prepared using Flexmaster, Mtwo Ni–Ti rotary systems respectively where Group III was prepared using hand NiTi flex-K files. Each group was further subdivided into three equal subgroups according to root canal final irrigation; subgroup A: SmearClear, subgroup B: 17% EDTA and subgroup C: NaOCl. Roots were then splitted longitudinally and processed for scanning electron microscopic (SEM) examination to evaluate and score the root canal cleanliness. ResultsFinal root canal irrigation using either SmearClear or 17% EDTA had significantly better cleaning efficiency than that of NaOCl in all tested groups. Ni–Ti hand files had significantly less cleaning efficacy than that of rotary systems except in subgroup C using NaOCl.

The effect of single‐file reciprocating systems on Substance P and Calcitonin gene‐related peptide expression in human periodontal ligament

To quantify the effect of two single-file reciprocating root canal preparation systems on Substance P (SP) and Calcitonin gene-related peptide (CGRP) expression in healthy human periodontal ligament (PDL). Forty PDL samples were obtained from healthy premolars where extraction was indicated for orthodontic reasons. Prior to extraction, 20 of these premolars were divided equally in two groups, and then, root canals were prepared using one of two different single-file systems: WaveOne and Reciproc. Ten premolars were prepared with hand files and served as a positive control group. The remaining 10 premolars where extracted without treatment and served as a negative control group. All PDL samples were processed, and SP and CGRP were measured by radioimmunoassay. Greater SP and CGRP expression were found in the hand instrumentation group (1.220 pmol SP and 0.084 pmol CGRP per mg of PDL), followed by the WaveOne group (0.908 pmol SP and 0.046 pmol CGRP per mg of PDL) and the Reciproc group (0.511 pmol SP and 0.022 pmol CGRP per mg of PDL). The lower SP and CGRP values were associated with the intact control group (0.453 pmol SP and 0.018 pmol CGRP per mg of PDL). The Kruskal-Wallis test revealed significant differences between groups (P < 0.001). Post hoc Tukey HSD tests revealed significant differences in SP and CGRP expression between intact teeth in the control group and all the other groups (P < 0.001) except with the Reciproc group (P = 0.165 and P = 0.42 for SP and CGRP, respectively). Hand instrumentation was associated with significant differences with all the other groups (P < 0.001). Differences between the WaveOne and Reciproc groups were also significant (P < 0.001). Substance P and CGRP expression in PDL cells increased when teeth were prepared with WaveOne as well as with hand instrumentation. Reciproc maintained SP and CGRP levels in line with the negative control group.

Problem solving in endodontic diseases: XII. Crucial factors in preparation of root canal system (II): irrigation and disinfection in endodontics

根管系统的解剖结构非常复杂,除主根管外还存在许多侧、副根管、根管分歧、管间峡部和网状交通支.在上一讲机械预备的作用环节中已阐明机械预备只是针对主根管的清理和成形[1],作为切削工具的锉针无法进入或触及那些细窄、不规则区域.对旋转镍钛锉所作根管预备效果的研究显示,CT三维重建的图像中35％以上的根管表面区域未被涉及(图1)[2],存在于这些部位的感染物质会滞留于根管中.在感染根管中,细菌除以悬浮的方式存在于根管空腔内,更主要的毒性状态是与胞外多糖基质聚合,黏附于根管壁形成细菌生物膜.在这种微生态环境中,协同共生的各种细菌可以充分发挥其致病毒性表征,甚至产生抗药性[3-5]。

Problem solving in endodontic diseases: XI. Crucial factors in preparation of root canal system (I): effect of canal instrumentation

根管治疗术是牙髓病、根尖周病首选治疗方法,其核心内容是有效控制根管系统内的感染.治疗操作从以下两个方面实现这一目标:一是去除感染源;二是杜绝再感染.前者通过根管预备过程中的机械清创和化学消毒最大限度地清除根管系统中的感染物质,包括外界侵入的感染源及其代谢产物和已受到感染的自体组织,与此同时还要防止感染的扩散和发展;后者则是通过根管充填对已清理、成形的根管严密封闭、堵塞空腔并使未被去除的极微量残余感染物无害化,防止其持续存留形成再感染[1].临床工作中,高质量完成根管预备和根管充填是根管治疗获得成功的必要条件,而不合格的根管充填,绝大多数是因根管预备不合格所致。

An in vitro comparison of root canal system prepared with either hand or rotary instruments.

The aim of the present study was to compare hand stainless steel K-files and Nickel-Titanium Profile 0.04 taper 29 series rotary instruments for their efficiency, procedural errors and time consumed in preparation of root canal system. A total of 46 maxillary and mandibular first premolars extracted for orthodontic purposes were collected (two contralateral teeth from each individual). The samples were divided into two groups of 34 canals each. Teeth in the first group were prepared with stainless steel hand K-files while the second groups were prepared with profile 0.04 taper series 29 rotary files. Preparation period was recorded for both groups. Impression material was introduced into the prepared canals so that the replica of prepared canals was achieved. These were assessed under stereomicroscope to assess the efficiency in preparing canals in respect to canal smoothness, ability of impression material to flow and quality of taper.Statistical analyses were performed using t-test, Chi-square and Fishers exact tests. RESULTS showed significantly shorter preparation time for Profile than K-file. 8.8% of the canals prepared with K-files showed canal blockage, while all canals prepared with Profile remained patent. Alterations in working length working distance appeared in 23.5% of canals prepared with K-file and 11.7% in canals prepared with Profile. Failed instruments in K-files were significantly higher, mostly deformation (P<0.001). Profiles failed instruments were in the form of fracture and no deformation was detected. Both systems showed unsatisfactory walls smoothness and flow. Within the limitation of this study it was concluded that Profile 0.04 taper series 29 rotary systems prepare canals more rapidly, and have lower incidences of fracture and blockages, and only limited loss of working length. Canal preparation with K-file was time consuming and showed higher incidence of deformed instruments; overall, rotary instruments seem to offer greater advantages.

The Effect of Three Different Rotary Instrumentation Systems on Substance P and Calcitonin Gene-related Peptide Expression in Human Periodontal Ligament

Introduction The purpose of this study was to quantify the effect of three different rotary root canal preparation systems on substance P and calcitonin gene-related peptide expression in healthy human periodontal ligament. Methods Fifty periodontal ligament samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Before extraction, 40 of these premolars were equally divided into four groups, and root canals were prepared using four different systems: the ProTaper Universal rotary system, the RaCe rotary system, the Mtwo rotary system, and the hand instrumentation technique. The remaining 10 healthy premolars that were extracted without treatment served as a negative control group. All periodontal ligament samples were processed, and SP and CGRP were measured by radioimmunoassay. Results Greater SP and CGRP expression were found in the ProTaper Universal group followed by the hand instrumentation group, the RaCe, and the Mtwo groups. The lower SP and CGRP values were for the negative control group. The Kruskal-Wallis test showed statistically significant differences between groups ( p < 0.0001). Post hoc Least Significant Difference (LSD) tests showed statistically significant differences in SP and CGRP expression between the negative control group and all the other groups except the Mtwo group. Hand instrumentation also showed statistically significant differences with all the other groups, except the ProTaper Universal group. Differences between the three rotary systems were also statistically significant. Conclusion SP and CGRP expression in periodontal ligament increases when teeth are prepared with ProTaper Universal and RaCe rotary instrumentation systems as well as with hand instrumentation. Mtwo maintains SP and CGRP levels.

FP Core Carrier Technique: Thermoplasticized Gutta-percha Root Canal Obturation Technique Using Polypropylene Core

Core carrier techniques are unique among the various root canal filling techniques for delivering and compacting gutta-percha in the prepared root canal system. Thermafil (TF), considered the major core carrier device, is provided as an obturator consisting of a master core coated with thermoplasticized gutta-percha. We have devised a thermoplasticized gutta-percha filling technique using a polypropylene core, FlexPoint® NEO (FP), which was developed as a canal filling material that can be sterilized in an autoclave. Therefore, FP can be coated onto thermoplasticized gutta-percha and inserted into the prepared canal as a core carrier. The FP core carrier technique offers many advantages over the TF system: the core can be tested in the root canal and verified radiographically; the core can be adjusted to fit and surplus material easily removed; furthermore the core can be easily removed for retreatment. The clinical procedure of the FP core carrier technique is simple, and similar that with the TF system. Thermoplasticized gutta-percha in a syringe is heated in an oven and extruded onto the FP core carrier after a trial insertion. The FP core carrier is inserted into the root canal to the working length. Excess FP is then removed with a red-hot plastic instrument at the orifice of the root canal. The FP core carrier technique incorporates the clinical advantages of the existing TF system while minimizing the disadvantages. Hence the FP core carrier technique is very useful in clinical practice. This paper describes the FP core carrier technique as a new core based method.

Fracture Resistance of Human Root Dentin Exposed to Intracanal Calcium Hydroxide

Abstract The purpose of the present study was to determine if exposure to intracanal calcium hydroxide [Ca(OH 2)] alters the fracture resistance of human root dentin. One hundred and two freshly extracted single rooted human teeth divided into three groups of 34 teeth each. Coronal access and endodontic instrumentation using round burs, stainless steel files, and Profile GT rotary files were completed for each tooth. The prepared root canal system of each tooth was filled with saline solution (group 1), USP Ca(OH) 2 (group 2), or Metapaste (group 3). The apicies and access openings were sealed with composite resin and the teeth were immersed in saline. After 30 days, the roots of 17 teeth from each group were sectioned horizontally into 1-mm thick disks and each disk was loaded to fracture at 2.5 mm/min with a SATEC universal-testing machine. After 180 days the same procedure was performed on the remaining 17 teeth in each of the 3 groups. The peak load at fracture was measured for each dentin disk. Data were analyzed using one-way ANOVA and a post hoc Student-Newman-Keuls test. After 30 days exposure to the test solution, there was no difference in the peak load at fracture for the three groups of teeth. However, after 180 days, the roots of the teeth exposed to USP Ca(OH) 2 showed a significant decrease in peak load at fracture when compared to the 30-day groups and the 180-day groups exposed to saline or Metapaste.