Access Cavity Design Research Articles

Impact of Access Cavity Design and Root Canal Taper on Fracture Resistance of Permanent Mandibular Molars: An In-vitro Study

Introduction: Minimal invasive endodontics in the form of conservative access designs and minimal root canal taper preparation have been devised to preserve tooth structure and increase fracture resistance. Aim: To assess the influence of two different access cavity designs and two different final preparation tapers on fracture resistance of mandibular molars. Materials and Methods: In this in-vitro study, performed over a period of two months, a total of 54 extracted human permanent mandibular first and second molar teeth with completely formed apices were selected and for infection control, the teeth were stored in 10% buffered formalin solution for two weeks before the experiment. The teeth were then randomly allocated into three groups, Group C where no tooth preparation was carried out, Group TAC in which traditional access cavity design was performed and Group TREC where Truss access cavity was performed. The groups TAC and TREC were further subdivided into subgroup A and B with two different tapers 0.04 and 0.06 taper preparations. Mesial canals of the teeth were chosen for testing the minimal root canal taper preparations. After apical gauging the distal canals, obturation and postendodontic restoration was carried out in all teeth of both the test groups. The teeth in all three groups were subjected to fracture testing in a universal testing machine. The data were recorded. Oneway Analysis of Variance (ANOVA) and Tukey Post-hoc test were used for statistical analysis. Results: The fracture resistance between group C and groups TAC and TREC and their subgroups were found to be statistically significant (p<0.05). However, there was no statistically significant difference (p>0.05) observed between the two test groups TAC and TREC and their subgroups. Conclusion: The conservative truss access design in combination with a reduced root canal taper preparation has shown to have produced better fracture resistance values in comparison to other groups and their subgroups although the results were not statistically significant.

A Literature Review of Minimally Invasive Endodontic Access Cavities - Past, Present and Future.

Minimally invasive endodontic access cavities have gained popularity in academic discussions for their clinical applications in recent years. Although some studies showed an improved fracture resistance of endodontically-treated teeth accessed with a minimally invasive access cavity design, the resulting effectiveness and efficiency of subsequent root canal treatment procedures may be impaired. Aspects that may be impaired are canal detection and negotiation, chemomechanical debridement of the root canal system, quality of the obturation. These are potentially complicated by the increased incidence of procedural mishaps and compromised aesthetic outcomes. In addition, the inherent flaws presented in the methodology of some in vitro studies and the lack of a universal classification system are also of concern. This literature review aims to present a comprehensive overview of the development of the minimally invasive endodontic access cavity and summarise the currently available from a clinical context.

A Comparison of Volume of Tissue Removed and Biomechanical Analysis of Different Access Cavity Designs in 2-rooted Mandibular First Molars: A Multisample 3-dimensional Finite Element Analysis

IntroductionThe aim of this study was to compare the biomechanical properties and the amount of coronal tissue removed among the different access cavities with a multisample 3-dimensional finite element analysis in the mandibular first molar. The correlation between the amount of tissue removed and the fracture resistance of the teeth was also analyzed. MethodsMicro-computed tomography data from 20 2-rooted mandibular first molars were included in this study as 3-dimensional modeling prototypes. Models of untreated molars and molars treated with the traditional access cavity (TradAC), the conservative access cavity (ConsAC), and the straight-line minimally invasive endodontic access cavities (SMIAC) were created. Each model was loaded in 3 ways to simulate the functional conditions of occlusion. The amount of tissue removed and the maximum stress in the cervical region were recorded and analyzed, and the correlation between them was also analyzed. ResultsThe amount of coronal tissue and pericervical dentin (PCD) removed in SMIAC and ConsAC was less than that of TradAC. The mean maximum stress in the cervical region was significantly smaller in SMIAC and ConsAC than in TradAC. The amount of hard tissue and PCD loss was positively correlated with the maximum stress in the cervical region of the tooth. ConclusionsIn mandibular first molars, it could be beneficial to improve the fracture resistance of the tooth after endodontic treatment by the minimally invasive access cavity to reduce the loss of coronal tooth tissue and PCD. The SMIAC may be an option balancing biomechanical properties and clinical convenience.

Do Conservative Access Cavity Designs Increase The Etiological Complications Incidence Rate? (in Vitro Study)

Do Conservative Access Cavity Designs Increase The Etiological Complications Incidence Rate? (in Vitro Study)

Efficacy of Root Canal Instrumentation and Fracture Strength Assessment in Primary Molars after Preparing Two Different Shapes of Access Cavity: An Ex Vivo Histological Study.

Aim and objectiveTo evaluate the efficacy of root canal instrumentation and fracture strength assessment in primary molars after preparing different shapes of access cavity design.Materials and methodsSixty extracted primary mandibular molars with at least 2/3rd roots were randomly, equally divided into two groups based on shapes of the access cavities; Group I: Traditional access cavity (TAC), Group II: Conservative access cavity (CAC). Each group was further subdivided into two subgroups with 15 samples each. After, root canal debridement, samples in subgroup 1 were sectioned for histological evaluation of root canal instrumentation efficacy, while subgroup 2 were assessed for fracture strength using a Universal Testing Machine. The data were analyzed statistically using Mann–Whitney and post hoc Tukey tests, with a p value <0.05.ResultsTraditional access cavity showed statistically significant root canal debridement efficacy (p < 0.05) compared with CAC. Statistically significant differences were obtained between fracture strength values among the two groups (p < 0.05), with considerably higher fracture strength in the CAC group than TAC.ConclusionTraditional access cavity design resulted in complete root canal debridement but caused weakening of tooth structure due to low fracture strength, necessitating the use of full coverage restoration postendodontic therapy.How to cite this articleSinghal Y, Srivastava N, Rana V, et al. Efficacy of Root Canal Instrumentation and Fracture Strength Assessment in Primary Molars after Preparing Two Different Shapes of Access Cavity: An Ex Vivo Histological Study. Int J Clin Pediatr Dent 2021;14(4):518–524.

Influence of conservative endodontic access cavities on instrumentation of oval-shaped straight root canals.

To evaluate the influence of the design of endodontic access cavities on the percentage of unprepared areas of canal walls and flexural fatigue of instruments activated by reciprocating movement in oval-shaped straight root canals of extracted teeth. Forty-two mandibular incisors with oval canals were scanned by a microcomputed tomography (micro-CT) device for homogeneous selection and distribution of the samples. Then, the teeth were divided into two groups (n=21) according to the design of access cavity being tested: ultraconservative endodontic access cavity (UltraAC) and traditional access cavity. The canals were accessed with the aid of a surgical microscope, instrumented with the WaveOne Gold Medium system and irrigated with 2.5% NaOCl and 17% EDTA. The unprepared areas of the canal wall were analysed by overlaying images before and after instrumentation and expressed as percentages. micro-CT data were analysed using t-test, Mann-Whitney and Wilcoxon tests. The endodontic instruments used during instrumentation were subjected to static flexural fatigue testing using an artificial stainless steel canal with a 60° angle of curvature and a radius of 5mm, located 5mm from the tip of the instrument. The instruments were activated until fracture occurred, and the time in seconds for the fracture was recorded using a digital timer. The number of cycles to fracture was calculated and analysed statistically. For flexural fatigue data, an anova test complemented by a Tukey range test was used. The significance level of 5% was used for all analyses. There was no significant difference between the groups related to unprepared areas by the instrument during canal preparation (p>.05). The difference in flexural fatigue resistance between the groups was not significant. The use of UltraAC did not interfere with the canal instrumentation of extracted mandibular incisors with straight and oval canals. There was no difference in the flexural fatigue resistance of the instruments in relation to access cavity design.

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.

Current strategies for conservative endodontic access cavity preparation techniques-systematic review, meta-analysis, and decision-making protocol.

To assess related studies and discuss the clinical implications of endodontic access cavity (AC) designs. A systematic review of studies comparing the fracture resistance and/or endodontic outcomes between different AC designs was conducted in two electronic search databases (PubMed and Web of Science) following the PRISMA guidelines. Study selection, data extraction, and quality assessment were performed. Meta-analyses were undertaken for fracture resistance and root canal detection, with the level of significance set at 0.05 (P = 0.05). A total of 33 articles were included in this systematic review. The global evaluation of the risk of bias in the included studies was assessed as moderate, and the level of evidence was rated as low. Four types of AC designs were categorized: traditional (TradAC), conservative (ConsAC), ultraconservative (UltraAC), and truss (TrussAC). Their impact on fracture resistance, cleaning/disinfection, procedural errors, root canal detection, treatment time, apical debris extrusion, and root canal filling was discussed. Meta-analysis showed that compared to TradAC, (i) there is a significant higher fracture resistance of teeth with ConsAC, TrussAC, or ConsAC/TrussAC when all marginal ridges are preserved (P < 0.05), (ii) there is no significant effect of the type of AC on the fracture resistance of teeth when one or two marginal ridges are lost (P > 0.05), and (iii) there is a significantly higher risk of undetected canals with ConsAC if not assisted by dental operating microscope and ultrasonic troughing (P < 0.05). Decreasing the AC extent does not necessarily present mechanical and biological advantages especially when one or more surfaces of the tooth structure are lost. To date, the evidence available does not support the application of TrussAC. UltraAC might be applied in limited occasions. Maintaining the extent of AC design as small as practical without jeopardizing the root canal treatment quality remains a pragmatic recommendation. Different criteria can guide the practitioner for the optimal extent of AC outline form which varies from case to case.

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.

Influence of Minimally Invasive Access Cavity Designs on the Fracture Resistance of Endodontically Treated Mandibular Molars Subjected to Thermocycling and Dynamic Loading

IntroductionThe aim of this study was to investigate the fracture resistance of endodontically treated and restored permanent mandibular molars with minimally invasive access cavities subjected to thermocycling and dynamic loading. MethodsForty first and second mandibular molars were randomly assigned to 4 groups (n = 10/group) as follows: group 1, control (intact teeth); group 2, traditional access cavity (TradAC); group 3, conservative access cavity (ConsAC); and group 4, truss access cavity (TrecAC). After endodontic treatment, teeth were restored with SDR core (Dentsply Caulk, Milford, DE) and subjected to thermocycling followed by dynamic and static loading with a multiaxial fatigue testing machine (Instron, Canton, MA). The maximum load to fracture and pattern of failure (restorable/unrestorable) were recorded. Data were evaluated with analysis of variance and the Tukey post hoc test for multiple comparisons. ResultsFracture resistance of the samples in the control group were higher than those in the experimental groups (P < .005). TradAC exhibited the least resistance to fracture (P < .005). There was no statistically significant difference in the fracture resistance of ConsAC and TrecAC (P = .361) Unrestorable fractures were more frequent in the TradAC group compared with all other groups. ConclusionsMandibular molars with ConsAC and TrecAC exhibited superior fracture resistance compared with TradAC. TradAC had the highest number of unrestorable fractures.

Effect of cervical lesion centered access cavity restored with short glass fibre reinforced resin composites on fracture resistance in human mandibular premolars- an in vitro study

AimThe aim of this study was to evaluate the fracture resistance of cervical lesion centered access cavity restored with short glass fibre reinforced resin materials in human mandibular premolars. Materials and methodsSixty freshly extracted human mandibular premolars were collected and assigned to positive control group (G1- Intact teeth) and other experimental groups (G2, G3. G4, G5, G6), Traditional Access Cavity(TAC) and Cervical Lesion Centered Access Cavity(CLCAC). Following endodontic therapy, samples were grouped accordingly, G2-CLCAC without restoration (Negative Control), G3-CLCAC restored with conventional nano-hybrid composite (Tetric-N-Ceram), G4-TAC restored with short glass fibre reinforced resin composite (Ever-X Posterior), G5-CLCAC restored with short glass fibre reinforced resin composite (Ever-X Posterior), G6- CLCAC restored with individually formed unidirectional fibre-reinforced post (Everstick post) and short glass fibre-reinforced resin composite (Ever-X Posterior). The samples were thermocycled (35 °C/28s, 15 °C/2s, 35 °C/28s, 45 °C/2s/10,000 cycles) and cyclically fatigued(2,50,000 cycles/15-30N/2 Hz) and then subsequently loaded to failure. The mean load to fracture (Newtons) were statistically analyzed using one-way ANOVA and Tukey's post HOC test and failure mode analysis was also done. ResultsThe mean fracture resistance of the CLCAC design restored with fibre reinforced materials was higher when compared to the TAC design but the difference was not statistically significant. The negative control group (CLCAC without restoration) showed significantly the least fracture resistance (P < 0.05) when compared to all the other groups except for group 3 (CLCAC restored with conventional composites). ConclusionsWithin the limitations of the study, it can be concluded that short glass fibre reinforced resin composites improved the fracture resistance of endodontically treated mandibular premolars irrespective of the type of access cavity designs. Favourable fractures were seen more in cervical lesion centered access cavity restored with short glass fibre reinforced composite materials. Nevertheless, the applicability of this design in multirooted teeth, canal cleanliness efficacy, and long term clinical performance are yet to be explored to complement this new access design.

Impact of Canal Taper and Access Cavity Design on the Life Span of an Endodontically Treated Mandibular Molar: A Finite Element Analysis

IntroductionThis study investigated the impact of different canal tapers and access cavity designs on the life span of endodontically treated mandibular first molars using the finite element method. MethodsFinite element analysis was performed on simulated models with 3 access cavity designs (traditional, conservative, and truss). The mesial canals were prepared to either constant tapers of 25/.04 and 25/.06 or a variable taper corresponding to the cumulative canal preparation shapes of TruNatomy Prime (Dentsply Sirona, Charlotte, NC) and ProTaper Gold F2 (Dentsply Sirona). The distal canals in all models had a 40/.04 preparation. Using occlusal fingerprint analysis, all models were subjected to cyclic occlusal loading until model failure. The number of cycles until failure, the location of failure, stress distribution patterns, and the maximum von Mises stresses were assessed. ResultsThe traditional access models showed a lower life span than the conservative and truss models regardless of the canal taper, whereas there was not a notable difference in the conservative and truss models. The stresses migrated apically along the root surface and remarkably on the mesial aspect of the mesial root and the furcation area’s outer surface. After root canal preparation with different tapers, there were no evident changes in the pattern and magnitude of the stresses distributed along the root surface. ConclusionsThe life span of the tooth is affected more significantly by the access cavity design than the root canal preparation taper. Because stress patterns migrate apically rather than concentrate in the pericervical area, crack initiation and propagation might occur anywhere on the root surface.

Digital Applications in Endodontics

The aim of this review was to provide an overview of the applications of digital dentistry technologies in endodontics, such as digital two-dimensional (2-D) and three-dimensional (3-D) imaging techniques, computer aided diagnosis (CAD) and improvement of artificial intelligence (AI) models, computer-controlled access cavity designs and 3-D printing applications. Advantages and disadvantages of these newly introduced technologies were discussed briefly with their indications. Apart from therapeutical or rehabilitative procedures, the use of digital technologies adapted for student training and research simulations were also presented.

GUIDED ENDODONTIC ACCESS

We have come a long way in dentistry from “extension for prevention” to “prevention of extension”. Asimilar approach in endodontics is going to change the future of dental practice with Minimal Invasive Endodontics (MIE). MIE mainly includes preservation of structural integrity of tooth, alternate access cavity designs, guided endodontic access, modern burs, cleaning and shaping, 3D irrigation and disinfection, magnication aids like loupes and dental operating microscope. Survival of an endodontically treated tooth depends mainly on its remaining structural integrity after access preparation. The concept of Conservative endodontic cavities (CEC) was introduced to preserve the pericervical dentin (PCD), which is crucial to transfer the occlusal load to the root. In traditional endodontic cavities (TEC) much of PCD is lost which reduces the fracture resistance of tooth. Guided endodontic access was introduced as an attempt to preserve the PCD. It ensures predictable outcome without any procedural errors. The present paper attempts to narratively summarize the scope of Guided endodontic access in dental practice and explain its benets to the practitioners compared with conventional technique

Influence of Access Cavity Design on Fatigue Resistance of Reciproc Blue: Conservative vs. Truss Access

Influence of Access Cavity Design on Fatigue Resistance of Reciproc Blue: Conservative vs. Truss Access

Traditional and minimally invasive access cavities in endodontics: a literature review.

The aim of this review was to evaluate the effects of different access cavity designs on endodontic treatment and tooth prognosis. Two independent reviewers conducted an unrestricted search of the relevant literature contained in the following electronic databases: PubMed, Science Direct, Scopus, Web of Science, and OpenGrey. The electronic search was supplemented by a manual search during the same time period. The reference lists of the articles that advanced to second-round screening were hand-searched to identify additional potential articles. Experts were also contacted in an effort to learn about possible unpublished or ongoing studies. The benefits of minimally invasive access (MIA) cavities are not yet fully supported by research data. There is no evidence that this approach can replace the traditional approach of straight-line access cavities. Guided endodontics is a new method for teeth with pulp canal calcification and apical infection, but there have been no cost-benefit investigations or time studies to verify these personal opinions. Although the purpose of MIA cavities is to reflect clinicians' interest in retaining a greater amount of the dental substance, traditional cavities are the safer method for effective instrument operation and the prevention of iatrogenic complications.

The Effect of Different Endodontic Access Cavity Designs on the Amount of Apically Extruded Debris

The Effect of Different Endodontic Access Cavity Designs on the Amount of Apically Extruded Debris

Impact of Access Cavity Design on Fracture Resistance of Endodontically Treated Molars: A Systematic Review.

ObjectiveThe main aim of this present systematic review is to ascertain whether a conservative endodontic cavity (ConsAC) has a better fracture resistance than a traditional access cavity (TradAC) in endodontically treated molars.Materials and MethodsThree independent reviewers researched without limits in multiple engines: PubMed, ScienceDirect, Scopus, ResearchGate, EBSCOhost, Wiley Online Library, and Google Scholar, in addition to reference and hand search. Articles were chosen according to a certain inclusion and exclusion criteria, which, in brief, are in vitro studies assessing the fracture resistance difference between ConsAC and TradAC performed on extracted sound human molar teeth. A quality assessment criteria was produced to evaluate the chosen articles and categorized them according to their risk of bias into low, moderate and high.ResultsOut of a total of 105 studies, which were obtained from seven different search engines, only eight in vitro studies were included after eliminating the duplicates followed by the application of the eligibility criteria. Five of the articles showed low risk of bias while the others revealed a moderate risk of bias.ConclusionTo sum up, there is insufficient evidence to give a final decision whether ConsAC is more advantageous than TradAC in terms of fracture resistance and further studies regarding this topic are needed.

A survey of current trends in root canal treatment: access cavity design and cleaning and shaping practices.

The purpose of this study was to evaluate current trends in access cavity design and cleaning and shaping among endodontists. A survey was e-mailed to active members of the American Association of Endodontists. Data showed that most respondents used traditional (57%) or conservative (43%) access cavities; less than 1% reported using ultraconservative access cavities. A glide path was created by 93% of respondents; NaOCl was used as lubricant by 51% of respondents, while 28% used RC Prep, 9% used liquid EDTA, 7% used Glyde, and 2% did not use any lubricant. Most respondents used NaOCl at 5.25% or higher concentration. Smear layer was removed by 92% of endodontists. Apical gauging was mostly accomplished with hand files. Clinical preferences varied among surveyed endodontists and among different age groups. Currently, very few endodontists use ultraconservative access preparations. There was large variation among the respondents suggesting a possible need for quality guidelines.

Controversies in endodontic access cavity design: A literature review

The purpose of this article is to compare and contrast the different types of endodontic access cavity designs based on the current available evidence. Four types of access cavity designs, namely, traditional endodontic access cavity design (TEC), contracted/conservative endodontic access cavity design (CEC), ultra-conservative or ninja endodontic access cavity design (NEC) and truss endodontic access cavity design (TREC) have been suggested, and the latter three are currently in the limelight. Studies in vitro have been performed comparing the TECs, CECs, TRECs and NECs; except for the TECs, the other three types have not undergone clinical trials on patients. The choice of endodontic access cavity design affects fracture strength of the tooth, but remnants of pulpal tissue, due to ineffective instrumentation, can cause root canal treatment failure. CPD/Clinical Relevance: Root canal treatment with new access cavity designs has been proposed. However, there is lack of evidence to support such practices. It is important to consider the potential deleterious effects of such access cavity designs rather than emphasizing the preservation of tooth structure alone.