Traditional Endodontic Cavity Research Articles

Assessment of Bacterial Load and Post-Endodontic Pain after One-Visit Root Canal Treatment Using Two Types of Endodontic Access Openings: A Randomized Controlled Clinical Trial.

The need for controlling bacteria and pain during root canal therapy is undeniable. This clinical trial aimed to assess whether there is a difference in colony-forming unit (CFU) reduction after instrumentation and post-endodontic pain after root canal treatment (RCT) using a traditional endodontic cavity (TEC) versus a conservative endodontic cavity (CEC). This clinical study was conducted on 89 patients designated for a single-visit RCT. Patients were allocated randomly (TEC n = 45 and CEC n = 44). The access opening was gained accordingly in each group by a single operator. A pre-instrumentation sample of root canal dentin was collected using an endodontic file; the second sample was collected similarly, right after shaping and cleaning the root canal. The CFU was calculated based on the samples collected. The pain level was recorded preoperatively and at 1, 7, and 21 days postoperatively utilizing a visual analog scale (VAS). There were no statistically significant differences in the CFU reduction between the TEC and CEC groups (p > 0.05). Additionally, there were no statistically significant differences found in postoperative pain levels between the TEC and CEC at 1, 7, and 21 days (p > 0.05). Despite the limitations of this study, both the CEC and TEC demonstrate a decrease in bacteria within the root canals and alleviate postoperative pain with no difference between them.

Comparative Evaluation of Different Endodontic Access Cavity Designs with Different Burs-An in vitro Experimental Insight into the Aspect of Fracture Resistance.

In vitro fracture resistance of extracted mandibular molars treated with various access cavity designs, including traditional endodontic cavity (TradAC), conservative/contracted endodontic cavity (ConsAC), ninja endodontic cavity (UltraAC), truss endodontic cavity (TrussAC), caries-driven access cavity (CariesAC), and intact teeth, is the focus of this study. Six groups of 20 mandibular molars, totaling 120, were used in the investigation. While the other five groups underwent various access cavity preparations, chemomechanical preparation, and obturation procedures before being repaired with composite resin, Group 1 was left unaltered (the control). A 6 mm round head tip was used to apply the fracture force, which was measured in newtons, at a crosshead speed of 1 mm/min until fracture developed. According to the current study, the intact control group had the maximum fracture resistance. The access cavity groups' mean values were maximum in CariesAC followed by ConsAC, TrussAC, UltraAC, and TraditonalAC respectively. While among the four minimally invasive designs, CariesAC showed a higher fracture resistance despite the results being statistically insignificant, TradAC had a significantly lower resistance than other conservative access cavity designs.

Impact of Contracted Endodontic Access Cavities on the Fracture Resistance of Endodontically Treated Teeth After Mechanical Aging by Simulated Chewing Forces

IntroductionThis in vitro study aimed to comparatively evaluate the fracture resistance of contracted endodontic cavities (CECs) versus traditional endodontic cavities (TECs) in mandibular molars after subjecting the samples to a chewing simulator. MethodsA total of 24 freshly extracted human mandibular molars were included in the study. Teeth with intact crowns and mature root apices that were devoid of caries, attrition, restorations, and cracks were selected and randomly assigned to 3 groups (n = 8) as follows: Group 1: TECs, Group 2: CECs, and Group 3: intact teeth (control group). After endodontic treatment, the teeth were restored with EverX bulk-fill composite and layered occlusally with nanohybrid composite SolareX and subjected to a chewing simulator where 240,000 masticatory cycles were simulated, which translates to 1 year of clinical function. The teeth were then subjected to static loading in a universal testing machine and the maximum load to fracture and the pattern of failure (restorable/unrestorable) were recorded. Data were evaluated with analysis of variance and the Tukey post hoc test for multiple comparisons. ResultsThe CEC group had higher fracture resistance when compared with the TEC group; however, the difference was not statistically significant. The fracture resistance of the samples in the control group was statistically higher than those in the experimental groups (P < .005). ConclusionsThere was no difference observed in the fracture resistance of mandibular molars with TECs and CECs subjected to masticatory loading.

Effect access cavity preparation and taper instrumentation on upper premolar fracture

Background : Fractures are the most undesirable thing in endodontically treated teeth. The main reason in endodontically treated teeth has a considerable risk for fractures is the loss of tooth structure. Objective : This study aims to determine the effect of access cavity preparation and instrument taper percentage on upper premolar fractures. Material and Methods : Twenty-four upper premolar samples were stored in sterile saline solution. The sample was divided into 2 large groups which were then divided into two groups for each group by random allocation. Twelve contracted endodontic cavity (CEC) preparations and the remaining twelve samples using traditional endodontic cavity (TEC) techniques. Each group was prepared with 6 samples 4% taper instrumentation and 6 samples 8% taper instrumentation. Each sample was irrigated with 5 ml of NaOCl. After that, the sample is tested using a universal testing machine. Result : The CEC group showed a significant reduction in fracture rates compared to the TEC group (p &lt;0.05), but there was no significant difference in the fracture in the tapering instrumentation (p&gt; 0.05). Conclusion : Preparation with the concept of minimally invasive CEC provides better resistance to fractures in the upper premolar while tapering instrumentation does not affect the fracture of the upper premolars.

Effect of access cavities on the biomechanics of mandibular molars: a finite element analysis

IntroductionThis study aimed to predict the fracture resistance of a mandibular first molar (MFM) with diverse endodontic cavities using finite element analysis (FEA).MethodsFive experimental finite element models representing a natural tooth (NT) and 4 endodontically treated MFMs were generated. Treated MFM models were with a traditional endodontic cavity (TEC) and minimally invasive endodontic (MIE) cavities, including guided endodontic cavity (GEC), contracted endodontic cavity (CEC) and truss endodontic cavity (TREC). Three loads were applied, simulating a maximum bite force of 600 N (N) vertically and a normal masticatory force of 225 N vertically and laterally. The distributions of von Mises (VM) stress and maximum VM stress were calculated.ResultsThe maximum VM stresses of the NT model were the lowest under normal masticatory forces. In endodontically treated models, the distribution of VM stress in GEC model was the most similar to NT model. The maximum VM stresses of the GEC and CEC models under different forces were lower than those of TREC and TEC models. Under vertical loads, the maximum VM stresses of the TREC model were the highest, while under the lateral load, the maximum VM stress of the TEC model was the highest.ConclusionThe stress distribution of tooth with GEC was most like NT. Compared with TECs, GECs and CECs may better maintain fracture resistance, TRECs, however, may have a limited effect on maintenance of the tooth resistance.

Quantifiable design and comparative evaluation of straight-line minimally invasive endodontic cavity based on the anatomical features of the coronal part of root canal

Background/purposeMinimally invasive endodontics has recently become popular in research. This study aimed to develop a new quantifiable straight-line minimally invasive endodontic cavity (SMIEC) for 3-rooted maxillary first molar based on the anatomical features of the coronal part of root canal. Materials and methodsCone-beam computed tomography (CBCT) images of 80 teeth were converted into models in Mimics Research software. Anatomical features of the coronal part of root canal were measured to develop SMIECs with straight-line accesses to root canals in 3-matic Research software. Twenty models were randomly sampled and each was duplicated for 8 simulation groups: non-treated (NT), traditional endodontic cavity (TEC), ninja endodontic cavity (NEC) and 5 SMIECs. Post-simulation models were subjected to finite element analysis to detect von-Mises stresses in ABAQUS software. ResultsDistributions of straight-line accesses to protogenetic root canals had certain manners, hence we developed 5 SMIECs. NEC and SMIECs had less hard tissue loss than TEC and presented different numerical rankings in different structures (P < 0.05). NEC had a less narrow surgery field than SMIECs except SMIEC2/4 (P < 0.05). The peak pericervical stresses of SMIECs were similar, lower than TEC and higher than NEC and NT (P < 0.05). The stress distributions of the 8 groups had certain manners. ConclusionFive SMIECs with straight-line accesses to root canals were developed, whose biomechanical properties were worse than NEC but better than TEC. Having appropriate structure preservation and surgery field, SMIEC2/4 was a preferred SMIEC.

Apically extruded debris, canal transportation, and shaping ability of nickel-titanium instruments on contracted endodontic cavities in molar teeth.

Apically extruded debris, canal transportation and shaping ability were compared between contracted endodontic cavities (CECs) and traditional endodontic cavities (TECs) after instrumentation with XP-endo Shaper (XPS), ProTaper Gold (PTG), ProTaper for hand-use (HPT) and Hero Shaper. The CECs or TECs groups were sub-divided into 24 groups according to root canal morphology and nickel-titanium (Ni-Ti) instruments. The weight of apically extruded debris was calculated using the Myers and Montgomery model. Pre- and postoperative images of teeth were scanned using micro-CT and the three-dimensional models were constructed and compared. Under CECs or TECs, XPS and PTG produced less apical debris and formed less canal transportation than HPT and Hero Shaper (P < 0.05). XPS group under CECs extruded less apical debris than that under TCEs for round canals with curvature of 20°-35° (P < 0.05). The centering ratios of four tested instruments were higher under TECs than those under CECs (P < 0.05). The HPT and Hero Shaper had more transportation under CECs than that under TCEs (P < 0.05). No statistical difference was found regarding shaping ability among all the groups. Under CECs, XPS preserves the original root canal anatomy, meanwhile it produces less apical debris than the other instruments.

Evaluation of Root Dentin Removal and Apical Debris Extrusion during Root Canal Preparation Related to the Different Endodontic Access Cavities: An In-vitro Study

Introduction: The restricted access cavity and the remaining roof of the pulp chamber may change the angle at which the instrument enters the root canal, which could have an impact on the effectiveness of chemo-mechanical canal preparation, potentially leading to endodontic mishaps. Aim: To evaluate the effect of the Traditional Endodontic Cavity (TEC) and Conservative Endodontic Cavity (CEC) on the amount of Root Dentin Removal (RDR) and the related Apical Debris Extrusion (ADE) in the curved root canals prepared with ProTaper Next (PTN) and TruNatomy (TN). Materials and Methods: The in-vitro study included a total of 120 extracted human mandibular molars, separated into four groups (n=30) based on the type of endodontic cavity and file used: TEC-TN, CEC-TN, TEC-PTN, and CEC-PTN. Before biomechanical preparation, Cone Beam Computed Tomography (CBCT) scans were taken. During the preparation, apically extruded debris was collected in Eppendorf tubes. After canal preparation, a post-CBCT scan was performed, and the RDR was evaluated by comparing the pre- and post-CBCT scans. To determine the amount of ADE, the weight of the clear tubes was subtracted from the weight of the tubes containing the debris. The data were analysed using one-way analysis of variance and post-hoc Tukey test. The significance level was set at p&lt;0.05. Results: Analysis and comparison of four groups each with n=-30 extracted mandibular molars was done in the present study. The CEC-PTN group showed the highest total RDR of 0.32. Additionally, the CEC-PTN group produced the highest ADE with statistically significant differences between the TECTN, CEC-TN, and TEC-PTN groups (p&lt;0.05). Conclusion: The CEC causes engagement of the rotary instrument with the dentinal wall, leading to RDR, debris production, and ultimately more ADE compared to TEC. The TN file caused less RDR and ADE in both endodontic access cavities compared to the PTN file.

Effect of different access cavity designs on fracture toughness of endodontically treated teeth: a systematic review and network meta-analysis.

Objective To compare the effect of different endodontic access cavities on fracture toughness of extracted endodontically treated human teeth.Data/sources An electronic literature search was performed in seven databases as well as hand search until September 2020. Risk-of-bias tool was used to evaluate the quality of included studies. Random effects frequentist network meta-analysis was performed, with mean difference (MD) and 95% confidence interval (CI) as the effect measure. Confidence in the documented evidence was assessed through the newly fuelled Confidence in Network Meta-analysis (CINeMA) framework based on the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.Study selection A total of 844 articles were obtained in the electronic and hand search. After the application of the eligibility criteria and duplicate removal, 14 studies were included in this systematic review. All included studies were in vitro that evaluated the influence of conservative endodontic cavities (CECs) on fracture toughness in extracted endodontically treated human teeth and compared to traditional endodontic cavities (TECs). In total, ten studies (n = 456) were included in the network meta-analysis for molars. The overall risk of bias was moderate.Results The results showed that when compared to intact teeth, the greatest reduction in fracture resistance was reported for TEC (MD: -927.52; 95% CI [-1304.80; -550.24]) and CEC showed least reduction in fracture resistance (MD: -365.59; 95% CI [-759.02; 27.83]). The surface under the cumulative ranking curve (SUCRA) value for intact teeth was highest (85.4% probability of being ranked as first), followed by CEC (51.4% probability of being ranked as second), with CEC presenting the highest probabilities to be the most effective access cavity design, according to the RANK (receptor activator of NF-kappaB) table. Level of confidence varied from low to moderate across all formulated comparisons.Conclusion Overall, based on the included in vitro studies in this systematic review, CEC was the most favourable access cavity design when compared to other (truss access cavities, TEC and ninja cavities) and TEC was the least favourable for fracture resistance; however, the level of evidence was moderate.

Effect of photon-induced photoacoustic streaming and shock-wave enhanced emission photoacoustic streaming technique on the removal of the smear layer after root canal preparation in curved root canals

The efficiency of root canal irrigation has an important impact on the prognosis of root canal treatment. Photon-induced photoacoustic streaming (PIPS) and shock wave enhanced emission photoacoustic streaming (SWEEPS) are the special modality of Er: YAG laser, whether can they improve the efficiency of root canal irrigation remains to be studied. Fifty human teeth with curved root canals were collected and stored in the thymol solution until used in the study. After traditional endodontic cavities preparation, root canals were prepared to size #35 with a 0.04 taper. The final irrigating techniques were as follows: (I) manual dynamic activation (MDA), (II) ultrasonically activated irrigation (UAI), (III) sonically activated irrigation (SAI), (IV) PIPS, and (V) SWEEPS. Fifty teeth were randomly divided into five groups mentioned above. After root canal preparation, the roots were cleaved longitudinally. The dentine surfaces were photographed from the coronal, middle, and apical third of the root by scanning electron microscopy operated at a low vacuum. Two examiners separately graded each image according to the remained smear layer situations. PIPS and SWEEPS groups showed fewer smear layers remaining than the others in the middle and the apical third (P< 0.05) of the root canal. In contrast, in the coronal third, five groups showed no significant difference (P>0.05). PIPS and SWEEPS showed superior smear layer clearing efficiency than traditional irrigating techniques in curved root canals.

Minimally invasive endodontics, an overview and current update

Introduction: The small access cavities could make it more difficult to visualize the pulp chamber as well as to locate, shape, clean and fill the canals. At the same time, increase the risk of iatrogenic complications. (Silva et al., 2020) Objective: To analyze the literature concerning the influence of minimally invasive endodontic access in pulp therapy, in relation to the degree of disinfection, degree of conformation, quality of obturation and resistance to the fracture. Methodology: By searching in electronic databases such as PubMed, using keywords: “minimally invasive endodontics”, “degree of disinfection”, “shaping”, “obturation” and “resistance to fracture”. Results: A true compromise of the degree of conformation of the canal is not demonstrated, although neither a benefit, when performing a contracted endodontic cavity (CEC). It is not possible to reach an adequate conclusion about the degree of disinfection in a CEC; priority should be given to a traditional endodontic cavity (TEC). Efficient canal obturation in CEC is limited to a single obturation technique, but if it is not intended to work under this protocol, the use of a TEC is suggested. No noticeable change in fracture strength is demonstrated in a CEC over a TEC.Conclusions: Success of endodontic treatment is represented by each of the stages that make up the procedure. CECs are an alteration to the traditional protocol and with it to the rest of the treatment stages.

Effect of Access Cavity Preparation on Dentin Preservation, Biomechanical Property, and Instrumentation Efficacy: A Micro–Computed Tomographic Study

IntroductionThe purpose of this study was to evaluate the influence of a contracted endodontic cavity (CEC) on dentin preservation, biomechanical property, and instrumentation efficacy of first permanent molars in comparison with a traditional endodontic cavity (TEC). MethodsForty-eight extracted intact maxillary and mandibular first molars were selected and scanned by micro–computed tomographic (micro-CT) imaging. Each tooth type was anatomically matched and assigned to the CEC group or the TEC group (n = 12). After root canal instrumentation with the ProGlider (Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Gold (Dentsply Maillefer), the specimens were scanned by micro-CT again. Pre- and postpreparation micro-CT imaging was used to evaluate the dentin preservation and instrumentation efficacy. The results on volume and thickness reduction in the coronal dentin and pericervical dentin (PCD), root canal volume and surface area, percentage of unprepared surface area, canal transportation and centering ratio, and canal wall thickness in the “danger zone” were measured and analyzed with the Shapiro-Wilk and independent sample t tests. Based on micro-CT imaging of maxillary and mandibular first molars, CEC and TEC models were constructed on the intact tooth, and 2 different static loads were applied to the occlusal load points. The stress distribution patterns and von Mises stress on the occlusal surface and cervical region were assessed by 3-dimensional finite element analysis. ResultsThe CEC had a significantly lower volume and thickness reduction of coronal dentin and PCD above the alveolar crest compared with the TEC group (P < .05), whereas no difference was observed in PCD below the alveolar crest between the 2 groups (P > .05). There was no difference regarding all instrumentation efficacy outcomes (root canal volume and surface area, percentage of unprepared surface area, canal transportation and centering ratio, and canal wall thickness) in the danger zone between the 2 groups (P > .05). The CEC effectively reduced the maximum von Mises stress and stress concentration area on the occlusal surface and cervical region compared with the TEC. ConclusionsThe CEC preserved more coronal dentin and PCD above the alveolar crest and thus reduced stress concentration on the occlusal surface and cervical region. The CEC had no significant adverse effects on the instrumentation efficacy compared with the TEC given that the instrumentation procedures were performed with ProGlider and WaveOne Gold files.

Impact of Different Access Cavity Designs and Ni–Ti Files on the Elimination of Enterococcus faecalis from the Root Canal System: An In Vitro Study

The present research aimed to reveal the in vitro effects of different endodontic file systems utilizing different endodontic access cavity designs on the elimination of Enterococcus faecalis from root canal systems. One hundred and fifty mandibular molar teeth were separated into three groups with respect to the access cavity design: traditional endodontic cavity (TEC), conservative endodontic cavity (CEC), and truss access cavity (TAC) (n = 50). After access cavity preparation, inolulation of teeth with E. faecalis was undertaken for 21 days. Following the first sampling (S1), further division of the groups into five subgroups (n = 10) was performed: ProTaper Gold, 2Shape, TruNatomy, Reciproc Blue, and WaveOne Gold. After instrumentation, bacterial sampling (S2) was performed. Bacterial reduction was evaluated in colony-forming units/mL, and statistical analysis was carried out. The E. faecalis count decreased significantly in all groups (p &lt; 0.05). The range of mean values for a decrease in E. faecalis in log numbers was lowest in the TAC and Reciproc Blue groups, while the highest values of bacterial reduction were detected in the TEC and ProTaper Gold groups. The highest level of antibacterial action was obtained with the use of ProTaper Gold compared to the other file systems tested.

Influence of the endodontic access cavity design and restorative technique on hard tissue removal and fracture resistance of mandibular premolars

This study assessed the influence of traditional (TradAC) and conservative access (ConsAC) with different restorative techniques on the percentage of hard tissue removed (%HTR) and on the fracture resistance of mandibular premolars. 45 premolars were scanned in a micro-computed tomography and assigned into four groups according to access (TradAC or ConsAC) and restorative technique: composite resin (CR) or fiber post (FP) + CR. After post preparation, the teeth were rescanned to determine the volume enlargement and %HTR from the crown and root canal. After restoration, the load at fracture was recorded. Data were analyzed statistically by one-way ANOVA and Tukey’s post-hoc test, ANOVA repeated measure, and chi-square tests (P&lt;0.05). TradAC (RC or FP) resulted in the increase (Δ%) of root canal volume and hard tissue removed up to 14 mm (%) in comparison with ConsAC (RC or FP). TradAC + FP removed a greater percentage of hard tissue from the crown when compared to TradAC + CR. The percentage of hard tissue removed in the crown in the ConsAC groups was statistically lower than in the TradAC groups. The control group showed higher fracture resistance than all experimental groups, with no differences among the latter. Restorable fracture patterns were more prevalent. Traditional endodontic access cavities removed a higher percentage of dentine than conservative endodontic access cavities. However, no differences in fracture resistance were observed. Restorations using composite resin or fiber post associated with composite resin showed similar results of fracture resistance.

In Vitro study of the effect of conservative endodontic cavities on fracture strength in mandibular molars using CBCT analysis

Background: Endodontically treated teeth with conservative cavity preparation show better fracture resistance than traditional designs. Objective: To compare the fracture strength of endodontically treated teeth using traditional endodontic cavity (TEC), conservative endodontic cavity (CEC), truss access cavity (DDC), and ninja endodontic cavity (NEC) access designs. Methods: In an in-vitro study, 50 freshly extracted human intact mandibular molars with two separate roots were selected. The anatomic crown height, buccolingual, and mesiodistal dimensions were measured and randomized to control (intact teeth), TEC, CEC, DDC, and NEC groups (n = 10). Using cone-beam computed tomography, TEC, CEC, DDC, and NEC access cavity outlines were planned. Following endodontic treatment, the fracture strength of teeth was assessed using a universal testing machine and fracture type with a stereomicroscope. Results: The mean volume percentage of the coronal hard tissue removal was significantly lower in the NEC group than in the TEC, and CEC groups (P < 0.05), while the difference was comparable between the NEC and DDC groups (P > 0.05). The fracture strength of teeth prepared with the TEC design was significantly lower than teeth prepared by CEC, DDC, NEC, and control groups (P < 0.05). Conclusion: Teeth with traditional access preparation showed lower fracture strength than the conservative approaches.

The effect of bulk-fill composites: Activa and Smart Dentin Replacement on cuspal deflection in endodontically treated teeth with different access cavity designs.

Aim:The aim was to evaluate the effect of bulk-fill composites – Activa and Smart Dentin Replacement (SDR) on cuspal deflection in endodontically treated teeth with different access cavity designs.Materials and Methods:Forty-two maxillary first premolar teeth were randomly divided into three experimental groups based on different access designs as Group I – conservative endodontic cavities (CECs), Group II – traditional endodontic cavities, and Group III – CECs with diverging walls and two subgroups, based on the different access cavity restorations subgroup A-Activa and subgroup B-SDR with n = 7 per group. Root canal treatment was completed under the dental operating microscope. Cuspal deflection was assessed by measuring the distance between the glass beads using an optical microscope and micrometer immediately after a Root canal treatment and final measurements after access restorations. Data were statistically analyzed and tabulated.Results:Results showed that the access cavity restored with Activa showed the highest cuspal deflection than SDR in all the groups (P < 0.05). Conservative access designs showed the least cuspal deflection among other groups.Conclusion:CEC designs showed lesser cuspal deflection than traditional endodontic cavity designs. SDR can be considered as a choice of material for access restorations.

Impact of Contracted Endodontic Access Cavity on Shaping Ability of Hyflex Electrical Discharge Machining Single File Using Cone Beam Computed Tomography: An Ex Vivo Study

AIM: The aim of the study was to evaluate and compare the effect of different access cavity designs, using cone-beam computed tomography (CBCT), on root canal transportation, and centralization performed on two rooted maxillary premolars. METHODS: Twenty maxillary premolars were randomly divided into two groups. In Group 1, traditional endodontic cavities (TECs) were prepared. In Group 2, contracted endodontic cavities (CECs) were prepared. Mechanical preparation was done by HyFlex electrical discharge machining (EDM) single file in both groups. CBCT imaging was performed pre- and post-root canal preparation for calculations of root canal transportation and centering ability. RESULTS: Data were analyzed using Mann–Whitney U test and Kruskal–Wallis test. For transportation, teeth with CECs showed the statistically significantly highest median amount of transportation, while as for centering ability, results showed no significant difference between both groups. CONCLUSION: Under the conditions of this study, HyFlex EDM prepared canals with different access cavity designs without significant shaping errors. TEC showed less transportation than CEC, while both TEC and CEC had no effect on the file centering ability.

The effects of endodontic access cavity design on dentine removal and effectiveness of canal instrumentation in maxillary molars.

To evaluate in a laboratory setting, the impact of three designs of endodontic access cavities on dentine removal and effectiveness of canal instrumentation in extracted maxillary first molars using micro-computed tomography (micro-CT). A total of 30 extracted intact maxillary first molars were selected and scanned by micro-CT with a voxel size of 24µm and randomly distributed into three groups: the traditional endodontic cavity (TEC) group, the conservative endodontic cavity (CEC) group and the guided endodontic cavity (GEC) group. The pulp chambers of teeth in the groups were accessed accordingly. After root canal preparation, the teeth were rescanned. The volume of dentine removed after canal preparation, the noninstrumented canal areas, canal transportation and centring ratio were analysed. Data were analysed statistically using one-way analysis of variance. Tukey's post hoc test was used for multiple comparisons. The significance level was set at p<.05. The total volume of dentine removed was significantly greater in the TEC group after root canal preparation (p<.05). No significant differences in the volume of dentine removed occurred between the CEC and GEC groups (p>.05). The volume of dentine removed in the crown, pericervical dentine and coronal third of the canal was significantly lower in CEC and GEC groups when compared to that in the TEC group (p<.05), no difference was observed in the middle third of the canal and apical third of the canal amongst the three groups (p>.05). There was no significant difference in noninstrumented canal area, canal transportation and centring ratio amongst the TEC, CEC and GEC groups (p>.05). In extracted maxillary molars tested in a laboratory setting, CEC and GEC preserved more tooth tissue in the crown, pericervical dentine and coronal third of the canal compared with TEC after root canal preparation. The design of the endodontic access cavity did not impact on the effectiveness of canal instrumentation in terms of noninstrumented canal area, canal transportation and centring ratio.

Fracture Stregnth of Endodontically Treated Teeth with Minimally Invasive Access Cavity Desgins Versus Conventional One (An In Vitro Study)

Aim: Assess the fracture strength of endodntically treated teeth with minimally invasive access cavitydesign versus conventional one.Methods: Forty four extracted molars were assigned to 4 groups. Conservative Access Cavity, Ninja AccessCavity, Truss Access Cavity, Traditional Access Cavity (n = 11/group/type). Teeth in the Traditional groupwere prepared following the principles of traditional endodontic cavities. Conservative access prepared byusing 2 periapical radiographs to determine canals location. Ninja access scans were plotted on cone beamcomputed tomographic images for localization of root canal orifices and Truss group were scanned, andmerged with cone beam computed tomography, for fabrication of an endodontic guide.The 44 specimenswere loaded to fracture in a universal material testing machine. The maximum load at which the teethfractured and fracture pattern (restorable or unrestorable) were recorded.Results: Regarding the fracture strength, results showed that there was a significant difference betweenNinja, Conservative,Truss and traditional access groups with (p &lt; 0.001) and no significant differencebetween Conservative and Truss groups. Regarding restorability, there was no statistical difference observedbetween the four groups with (p &lt; 0.001).Conclusion: Teeth with traditional access showed lower fracture strength than the ones prepared withConservative, Ninja and Truss.

Comparative evaluation of the fracture resistance of endodontically treated teeth with different access designs

Background: Most important step for successful endodontic treatment is access cavity preparation. However, the removal of tooth structure needed for access cavity leads to compromise of pericervical dentin and remaining dentin thickness undermining the strength of tooth and increasing the root fracture propensity under functional loads. Therefore, in the present study fracture resistance of endodontically treated teeth with Traditional endodontic cavity [TEC] to Conservative endodontic cavity [CEC] and pericervical bonding of composite resin in different root filled teeth was evaluated by using Universal Testing Machine. Materials and Methods: Freshly extracted single rooted premolars were selected and randomly divided into two groups: Group 1: Traditional Endodontic Cavity (TEC) (n=24) Group 2: Conservative endodontic cavity (CEC) (n=24) 1. GROUP 1a: TEC restored with Cavit 2. GROUP 1b: TEC restored with nanocomposite 3. GROUP 2a: CEC restored with Cavit 4. GROUP 2b: CEC restored with nanocomposite 5. The specimens were then loaded to fracture in Instron Universal Testing machine and the fracture resistance data was further analysed and compared. Results: The mean fracture strength for CEC restored with nanocomposite was significantly higher than all the other groups. (p