Journal of Clinical and Diagnostic Research, ISSN - 0973 - 709X

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Dr Mohan Z Mani

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Professor & Head,
Department of Dermatolgy,
Believers Church Medical College,
Thiruvalla, Kerala
On Sep 2018




Prof. Somashekhar Nimbalkar

"Over the last few years, we have published our research regularly in Journal of Clinical and Diagnostic Research. Having published in more than 20 high impact journals over the last five years including several high impact ones and reviewing articles for even more journals across my fields of interest, we value our published work in JCDR for their high standards in publishing scientific articles. The ease of submission, the rapid reviews in under a month, the high quality of their reviewers and keen attention to the final process of proofs and publication, ensure that there are no mistakes in the final article. We have been asked clarifications on several occasions and have been happy to provide them and it exemplifies the commitment to quality of the team at JCDR."



Prof. Somashekhar Nimbalkar
Head, Department of Pediatrics, Pramukhswami Medical College, Karamsad
Chairman, Research Group, Charutar Arogya Mandal, Karamsad
National Joint Coordinator - Advanced IAP NNF NRP Program
Ex-Member, Governing Body, National Neonatology Forum, New Delhi
Ex-President - National Neonatology Forum Gujarat State Chapter
Department of Pediatrics, Pramukhswami Medical College, Karamsad, Anand, Gujarat.
On Sep 2018




Dr. Kalyani R

"Journal of Clinical and Diagnostic Research is at present a well-known Indian originated scientific journal which started with a humble beginning. I have been associated with this journal since many years. I appreciate the Editor, Dr. Hemant Jain, for his constant effort in bringing up this journal to the present status right from the scratch. The journal is multidisciplinary. It encourages in publishing the scientific articles from postgraduates and also the beginners who start their career. At the same time the journal also caters for the high quality articles from specialty and super-specialty researchers. Hence it provides a platform for the scientist and researchers to publish. The other aspect of it is, the readers get the information regarding the most recent developments in science which can be used for teaching, research, treating patients and to some extent take preventive measures against certain diseases. The journal is contributing immensely to the society at national and international level."



Dr Kalyani R
Professor and Head
Department of Pathology
Sri Devaraj Urs Medical College
Sri Devaraj Urs Academy of Higher Education and Research , Kolar, Karnataka
On Sep 2018




Dr. Saumya Navit

"As a peer-reviewed journal, the Journal of Clinical and Diagnostic Research provides an opportunity to researchers, scientists and budding professionals to explore the developments in the field of medicine and dentistry and their varied specialities, thus extending our view on biological diversities of living species in relation to medicine.
‘Knowledge is treasure of a wise man.’ The free access of this journal provides an immense scope of learning for the both the old and the young in field of medicine and dentistry as well. The multidisciplinary nature of the journal makes it a better platform to absorb all that is being researched and developed. The publication process is systematic and professional. Online submission, publication and peer reviewing makes it a user-friendly journal.
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I wish JCDR a great success and I hope that journal will soar higher with the passing time."



Dr Saumya Navit
Professor and Head
Department of Pediatric Dentistry
Saraswati Dental College
Lucknow
On Sep 2018




Dr. Arunava Biswas

"My sincere attachment with JCDR as an author as well as reviewer is a learning experience . Their systematic approach in publication of article in various categories is really praiseworthy.
Their prompt and timely response to review's query and the manner in which they have set the reviewing process helps in extracting the best possible scientific writings for publication.
It's a honour and pride to be a part of the JCDR team. My very best wishes to JCDR and hope it will sparkle up above the sky as a high indexed journal in near future."



Dr. Arunava Biswas
MD, DM (Clinical Pharmacology)
Assistant Professor
Department of Pharmacology
Calcutta National Medical College & Hospital , Kolkata




Dr. C.S. Ramesh Babu
" Journal of Clinical and Diagnostic Research (JCDR) is a multi-specialty medical and dental journal publishing high quality research articles in almost all branches of medicine. The quality of printing of figures and tables is excellent and comparable to any International journal. An added advantage is nominal publication charges and monthly issue of the journal and more chances of an article being accepted for publication. Moreover being a multi-specialty journal an article concerning a particular specialty has a wider reach of readers of other related specialties also. As an author and reviewer for several years I find this Journal most suitable and highly recommend this Journal."
Best regards,
C.S. Ramesh Babu,
Associate Professor of Anatomy,
Muzaffarnagar Medical College,
Muzaffarnagar.
On Aug 2018




Dr. Arundhathi. S
"Journal of Clinical and Diagnostic Research (JCDR) is a reputed peer reviewed journal and is constantly involved in publishing high quality research articles related to medicine. Its been a great pleasure to be associated with this esteemed journal as a reviewer and as an author for a couple of years. The editorial board consists of many dedicated and reputed experts as its members and they are doing an appreciable work in guiding budding researchers. JCDR is doing a commendable job in scientific research by promoting excellent quality research & review articles and case reports & series. The reviewers provide appropriate suggestions that improve the quality of articles. I strongly recommend my fraternity to encourage JCDR by contributing their valuable research work in this widely accepted, user friendly journal. I hope my collaboration with JCDR will continue for a long time".



Dr. Arundhathi. S
MBBS, MD (Pathology),
Sanjay Gandhi institute of trauma and orthopedics,
Bengaluru.
On Aug 2018




Dr. Mamta Gupta,
"It gives me great pleasure to be associated with JCDR, since last 2-3 years. Since then I have authored, co-authored and reviewed about 25 articles in JCDR. I thank JCDR for giving me an opportunity to improve my own skills as an author and a reviewer.
It 's a multispecialty journal, publishing high quality articles. It gives a platform to the authors to publish their research work which can be available for everyone across the globe to read. The best thing about JCDR is that the full articles of all medical specialties are available as pdf/html for reading free of cost or without institutional subscription, which is not there for other journals. For those who have problem in writing manuscript or do statistical work, JCDR comes for their rescue.
The journal has a monthly publication and the articles are published quite fast. In time compared to other journals. The on-line first publication is also a great advantage and facility to review one's own articles before going to print. The response to any query and permission if required, is quite fast; this is quite commendable. I have a very good experience about seeking quick permission for quoting a photograph (Fig.) from a JCDR article for my chapter authored in an E book. I never thought it would be so easy. No hassles.
Reviewing articles is no less a pain staking process and requires in depth perception, knowledge about the topic for review. It requires time and concentration, yet I enjoy doing it. The JCDR website especially for the reviewers is quite user friendly. My suggestions for improving the journal is, more strict review process, so that only high quality articles are published. I find a a good number of articles in Obst. Gynae, hence, a new journal for this specialty titled JCDR-OG can be started. May be a bimonthly or quarterly publication to begin with. Only selected articles should find a place in it.
An yearly reward for the best article authored can also incentivize the authors. Though the process of finding the best article will be not be very easy. I do not know how reviewing process can be improved. If an article is being reviewed by two reviewers, then opinion of one can be communicated to the other or the final opinion of the editor can be communicated to the reviewer if requested for. This will help one’s reviewing skills.
My best wishes to Dr. Hemant Jain and all the editorial staff of JCDR for their untiring efforts to bring out this journal. I strongly recommend medical fraternity to publish their valuable research work in this esteemed journal, JCDR".



Dr. Mamta Gupta
Consultant
(Ex HOD Obs &Gynae, Hindu Rao Hospital and associated NDMC Medical College, Delhi)
Aug 2018




Dr. Rajendra Kumar Ghritlaharey

"I wish to thank Dr. Hemant Jain, Editor-in-Chief Journal of Clinical and Diagnostic Research (JCDR), for asking me to write up few words.
Writing is the representation of language in a textual medium i e; into the words and sentences on paper. Quality medical manuscript writing in particular, demands not only a high-quality research, but also requires accurate and concise communication of findings and conclusions, with adherence to particular journal guidelines. In medical field whether working in teaching, private, or in corporate institution, everyone wants to excel in his / her own field and get recognised by making manuscripts publication.


Authors are the souls of any journal, and deserve much respect. To publish a journal manuscripts are needed from authors. Authors have a great responsibility for producing facts of their work in terms of number and results truthfully and an individual honesty is expected from authors in this regards. Both ways its true "No authors-No manuscripts-No journals" and "No journals–No manuscripts–No authors". Reviewing a manuscript is also a very responsible and important task of any peer-reviewed journal and to be taken seriously. It needs knowledge on the subject, sincerity, honesty and determination. Although the process of reviewing a manuscript is a time consuming task butit is expected to give one's best remarks within the time frame of the journal.
Salient features of the JCDR: It is a biomedical, multidisciplinary (including all medical and dental specialities), e-journal, with wide scope and extensive author support. At the same time, a free text of manuscript is available in HTML and PDF format. There is fast growing authorship and readership with JCDR as this can be judged by the number of articles published in it i e; in Feb 2007 of its first issue, it contained 5 articles only, and now in its recent volume published in April 2011, it contained 67 manuscripts. This e-journal is fulfilling the commitments and objectives sincerely, (as stated by Editor-in-chief in his preface to first edition) i e; to encourage physicians through the internet, especially from the developing countries who witness a spectrum of disease and acquire a wealth of knowledge to publish their experiences to benefit the medical community in patients care. I also feel that many of us have work of substance, newer ideas, adequate clinical materials but poor in medical writing and hesitation to submit the work and need help. JCDR provides authors help in this regards.
Timely publication of journal: Publication of manuscripts and bringing out the issue in time is one of the positive aspects of JCDR and is possible with strong support team in terms of peer reviewers, proof reading, language check, computer operators, etc. This is one of the great reasons for authors to submit their work with JCDR. Another best part of JCDR is "Online first Publications" facilities available for the authors. This facility not only provides the prompt publications of the manuscripts but at the same time also early availability of the manuscripts for the readers.
Indexation and online availability: Indexation transforms the journal in some sense from its local ownership to the worldwide professional community and to the public.JCDR is indexed with Embase & EMbiology, Google Scholar, Index Copernicus, Chemical Abstracts Service, Journal seek Database, Indian Science Abstracts, to name few of them. Manuscriptspublished in JCDR are available on major search engines ie; google, yahoo, msn.
In the era of fast growing newer technologies, and in computer and internet friendly environment the manuscripts preparation, submission, review, revision, etc and all can be done and checked with a click from all corer of the world, at any time. Of course there is always a scope for improvement in every field and none is perfect. To progress, one needs to identify the areas of one's weakness and to strengthen them.
It is well said that "happy beginning is half done" and it fits perfectly with JCDR. It has grown considerably and I feel it has already grown up from its infancy to adolescence, achieving the status of standard online e-journal form Indian continent since its inception in Feb 2007. This had been made possible due to the efforts and the hard work put in it. The way the JCDR is improving with every new volume, with good quality original manuscripts, makes it a quality journal for readers. I must thank and congratulate Dr Hemant Jain, Editor-in-Chief JCDR and his team for their sincere efforts, dedication, and determination for making JCDR a fast growing journal.
Every one of us: authors, reviewers, editors, and publisher are responsible for enhancing the stature of the journal. I wish for a great success for JCDR."



Thanking you
With sincere regards
Dr. Rajendra Kumar Ghritlaharey, M.S., M. Ch., FAIS
Associate Professor,
Department of Paediatric Surgery, Gandhi Medical College & Associated
Kamla Nehru & Hamidia Hospitals Bhopal, Madhya Pradesh 462 001 (India)
E-mail: drrajendrak1@rediffmail.com
On May 11,2011




Dr. Shankar P.R.

"On looking back through my Gmail archives after being requested by the journal to write a short editorial about my experiences of publishing with the Journal of Clinical and Diagnostic Research (JCDR), I came across an e-mail from Dr. Hemant Jain, Editor, in March 2007, which introduced the new electronic journal. The main features of the journal which were outlined in the e-mail were extensive author support, cash rewards, the peer review process, and other salient features of the journal.
Over a span of over four years, we (I and my colleagues) have published around 25 articles in the journal. In this editorial, I plan to briefly discuss my experiences of publishing with JCDR and the strengths of the journal and to finally address the areas for improvement.
My experiences of publishing with JCDR: Overall, my experiences of publishing withJCDR have been positive. The best point about the journal is that it responds to queries from the author. This may seem to be simple and not too much to ask for, but unfortunately, many journals in the subcontinent and from many developing countries do not respond or they respond with a long delay to the queries from the authors 1. The reasons could be many, including lack of optimal secretarial and other support. Another problem with many journals is the slowness of the review process. Editorial processing and peer review can take anywhere between a year to two years with some journals. Also, some journals do not keep the contributors informed about the progress of the review process. Due to the long review process, the articles can lose their relevance and topicality. A major benefit with JCDR is the timeliness and promptness of its response. In Dr Jain's e-mail which was sent to me in 2007, before the introduction of the Pre-publishing system, he had stated that he had received my submission and that he would get back to me within seven days and he did!
Most of the manuscripts are published within 3 to 4 months of their submission if they are found to be suitable after the review process. JCDR is published bimonthly and the accepted articles were usually published in the next issue. Recently, due to the increased volume of the submissions, the review process has become slower and it ?? Section can take from 4 to 6 months for the articles to be reviewed. The journal has an extensive author support system and it has recently introduced a paid expedited review process. The journal also mentions the average time for processing the manuscript under different submission systems - regular submission and expedited review.
Strengths of the journal: The journal has an online first facility in which the accepted manuscripts may be published on the website before being included in a regular issue of the journal. This cuts down the time between their acceptance and the publication. The journal is indexed in many databases, though not in PubMed. The editorial board should now take steps to index the journal in PubMed. The journal has a system of notifying readers through e-mail when a new issue is released. Also, the articles are available in both the HTML and the PDF formats. I especially like the new and colorful page format of the journal. Also, the access statistics of the articles are available. The prepublication and the manuscript tracking system are also helpful for the authors.
Areas for improvement: In certain cases, I felt that the peer review process of the manuscripts was not up to international standards and that it should be strengthened. Also, the number of manuscripts in an issue is high and it may be difficult for readers to go through all of them. The journal can consider tightening of the peer review process and increasing the quality standards for the acceptance of the manuscripts. I faced occasional problems with the online manuscript submission (Pre-publishing) system, which have to be addressed.
Overall, the publishing process with JCDR has been smooth, quick and relatively hassle free and I can recommend other authors to consider the journal as an outlet for their work."



Dr. P. Ravi Shankar
KIST Medical College, P.O. Box 14142, Kathmandu, Nepal.
E-mail: ravi.dr.shankar@gmail.com
On April 2011
Anuradha

Dear team JCDR, I would like to thank you for the very professional and polite service provided by everyone at JCDR. While i have been in the field of writing and editing for sometime, this has been my first attempt in publishing a scientific paper.Thank you for hand-holding me through the process.


Dr. Anuradha
E-mail: anuradha2nittur@gmail.com
On Jan 2020

Important Notice

Original article / research
Year : 2023 | Month : January | Volume : 17 | Issue : 1 | Page : ZC20 - ZC25 Full Version

Comparative Cone Beam Computed Tomographic Evaluation of Conventional and Conservative Endodontic Access Cavity Designs on Pericervical Dentin Thickness and Fracture Resistance of Teeth: An In-vitro Study


Published: January 1, 2023 | DOI: https://doi.org/10.7860/JCDR/2023/59873.17261
Aashray Patel, Vaishali Parekh, Chintan Joshi, Niraj Kinariwala, Sweety Thumar, Mona Somani, Ankita Khunt, Neelam Desai

1. Assistant Professor, Department of Conservative Dentistry and Endodontics, Karnavati School of Dentistry, Karnavati University, Ahmedabad, Gujarat, India. 2. Former Professor and Head, Department of Conservative Dentistry and Endodontics, Karnavati School of Dentistry, Ahmedabad, Gujarat, India. 3. Professor and Head, Department of Conservative Dentistry and Endodontics, Karnavati School of Dentistry, Ahmedabad, Gujarat, India. 4. Associate Professor, Department of Conservative Dentistry and Endodontics, Karnavati School of Dentistry, Ahmedabad, Gujarat, India.' 5. Associate Professor, Department of Conservative Dentistry and Endodontics, Karnavati School of Dentistry, Ahmedabad, Gujarat, India. 6. Associate Professor, Department of Conservative Dentistry and Endodontics, Karnavati School of Dentistry, Ahmedabad, Gujarat, India. 7. Assistant Professor, Department of Conservative Dentistry and Endodontics, Karnavati School of Dentistry, Ahmedabad, Gujarat, India. 8. Senior

Correspondence Address :
Dr. Aashray Patel,
37, Swagat Bunglows, Ramosana Road, Mahesana, Gujarat- 384002, India.
E-mail: aashray@karnavatiuniversity.edu.in

Abstract

Introduction: The concept of ‘extension for prevention’ accelerates treatment processes but eliminates precious dentin at the pericervical area, resulting in biomechanically weakened tooth structure after endodontic treatment. Pericervical Dentin (PCD) is a new paradigm for endodontic success supports the idea that the amount of residual tooth structure is closely associated with long-term retention of the tooth and resistance to fracturing.

Aim: To determine the impact of two endodontic access cavity designs and biomechanical preparation on the pericervical dentin thickness using 3D Cone Beam Computed Tomographic (CBCT) visualisation technique and fracture resistance of the maxillary anterior teeth under compressive load using universal testing machine.

Materials and Methods: The in-vitro study was conducted in the Department of Conservative Dentistry and Endodontics at Karnavati School of Dentistry, Gandhinagar, Gujarat, India, from October 2020 to March 2021. Study was carried out on the 30 single rooted freshly extracted maxillary central incisors and were randomly divided into two groups of conventional and conservative access preparation groups (n=15). Group 1 was conventional group, samples were accessed using endo access bur #1. Group 2 was conservative group, samples were accessed using CK micro-endodontic bur under a dental operating microscope. Cleaning and shaping was done using 17% Ethylenediamine Tetraacetic Acid (EDTA) as lubricant and 4% Hyflex CM rotary file system. The CBCT scans were taken preoperatively, following access cavity preparation and postobturation to evaluate the amount of pericervical dentin loss in mesial, lingual, facial and distal surfaces of the teeth at the levels of 1 mm to 4 mm above and below Cementoenamel Junction (CEJ). The samples were then loaded to fracture in the Universal Testing Machine, and the data were analysed using Independent sample t-test using Statistical Package for Social Sciences (SPSS) software version 20.0.

Results: In comparison to the group 2, group 1 led to an increase in substantial tooth structure loss in the pericervical region. Among all surfaces, pericervical dentin loss was more pronounced on the lingual surface in the group 1 than in the group 2 (p-value <0.001). Higher fracture resistance was observed in group 2 (1136.75 N) compared to group 1 (687.22 N) under compressive load (p-value <0.001).

Conclusion: Incisal cavity design is a less invasive method of accessing maxillary central incisors that preserves pericervical dentin. Under compressive load, pericervical dentin conservation provided greater fracture resistance in the conservative group than in the conventional group.

Keywords

Incisal cavity design, Dental operating microscope, Minimal invasive endodontics, Pericervical dentin, Universal testing machine

Minimal Invasive Endodontics (MIE) is an approach that aims to keep healthy coronal, cervical, and radicular tooth structure intact during endodontic treatment. It refers to the removal of dentin as minimal as possible during all three phases of a root canal procedure (1), coronal access preparation, (2) radicular apical preparation, and (3) flaring of the channel that joins the coronal and apical preparations. Pericervical dentin was first defined by Clark D and Khademi J, in accordance with this new integrated paradigm for endodontically treated tooth restorability. It is an area which extends 4 mm above and 4 mm below to the crestal bone (1),(2).

The conventional access cavity preparation for maxillary central and lateral incisor is located just above the cingulum. This design has several drawbacks and does not fulfill the main principles of access preparation. It leads to increased tooth structure loss in the pericervical region which compromises the fracture resistance of the tooth (3),(4). Hence, GG drills and large round burs should not be used since they are not self-centred, cause gouging, which makes negotiating the canals difficult, and are not minimally invasive because they cut excessive pericervical dentin (1).

To overcome this, Clark D et al., proposed a new concept of conservative endodontic access cavity on dentin preservation to address the difficulties raised above (1). One such variation in access cavity design is the “incisal approach.” It allows for a straight line and unobstructed access to the apical third of the root, lowering the risk of perforation and improving preparation, particularly in the apical third of the canal (5). Using a CK micro-endodontic access bur with a round ended tapered design, it allows for the construction of complete funnel with its narrowest portion remains in the pericervical dentin region. These burs have a tip size that is less than half the width of a round carbide bur (6),(7).

Cone Beam Computed Tomography (CBCT) employs an extraoral imaging scanner that provides 3D volumetric details in limited field of view images to precisely measure pericervical dentin thickness in both orthogonal and oblique planes while emitting significantly less radiation than conventional digital radiographs (8),(9).

The incisal approach and its impact on the pericervical dentin in maxillary anterior teeth utilising CBCT are topics of limited knowledge in the literature review (10),(11),(12). Therefore, the aim of the study was to compare and evaluate the amount of pericervical dentin thickness by CBCT and fracture resistance between the conventional access cavity design and the conservative access cavity design.

The null hypothesis was that there is no difference in the pericervical dentin thickness and fracture resistance between conventional and conservative access cavity preparation.

Material and Methods

The in-vitro study was conducted in the Department of Conservative Dentistry and Endodontics at Karnavati School of Dentistry, Oroscan CBCT centre, Gandhinagar and Ahmedabad Textile Industries Research Association (ATIRA), Ahmedabad, Gujarat, India, from October 2020 to March 2021.This study was approved by Karnavati School of Dentistry Ethical Committee (KSDEC/19-20/Apr/021).

Sample size calculation: The study considered the data based on previous study (13) on evaluation of the strength of endodontically treated teeth after preservation of pericervical dentin where a difference between two groups reached statistical significance with samples of 15 teeth/group. Accordingly, a sample size of 15 teeth/group was used in the present study to analyse data with 80% power and 5% significance using statistical power analysis.

Inclusion criteria: The study included single rooted fully matured intact maxillary central incisors extracted for poor periodontal conditions.

Exclusion criteria: Teeth with immature apex, internal resorption, calcified canals, carious lesion, cracks and any other developmental anomalies were excluded from the study.

Study Procedure

All the teeth were immersed in 10% formalin solution (for not longer than two weeks after extraction) and then all samples were cleaned with ultrasonic scalers to remove organic debris and deposits. All teeth were kept in 3% Sodium hypochlorite (NaOCl) for two hours and stored into 0.9% normal saline solution until they are used.

A customised U-shape mounter was made from hard modelling to simulate the jaw conditions (Table/Fig 1). All the teeth were placed on mounter to standardise the angulations and position of the samples for CBCT scans. All the teeth were recorded for preoperative CBCT scans for determining pericervical dentin thickness extending up to 4 mm above CEJ and 4 mm below CEJ. Recordings were done at 1 mm, 2 mm, 3 mm and 4 mm from Cementoenamel Junction (CEJ). It was determined as the shortest distance between the root canal outline (A1) and the nearest adjacent root surface (B1) (Table/Fig 2).

Thirty teeth were divided into two groups of 15 each. For both the groups, access opening was performed under Dental Operating Microscope (DOM) (Table/Fig 3),(Table/Fig 4).

• Group 1: Conventional access opening
• Group 2: Conservative access opening

Group 1: Endo access bur #1 (Dentsply Maillefer, Ballaigues, Switzerland) was used to make the initial site of entry into the tooth, which was kept just above the cingulum. The bur was initially angled perpendicular to the long axis of the tooth, and it was later oriented parallel to the long axis of the tooth to remove the roof of the pulp chamber. The access was roughly extended with the bur after finding the canal to form an oval shape.

Group 2: Conservative access cavity preparation was performed under Dental Operating Microscope with the initial point of entry with the EG5 CK bur (SS White, New Jersey, USA) was held parallel to the long axis of the tooth and maintained short of the incisal edge on the lingual surface of the crown. The cavity was expanded cervically to the centre of the lingual surface, involving incisally half of the bucco-lingual width of the incisal edge and including the entire pulp chamber mesiodistally.

Following access preparation for both the groups, a second CBCT scan was taken for the evaluation of pericervical dentin at 1 mm to 4 mm from CEJ. Canal patency was made using 10 no K-file and working length was determined using periapical RadioVisioGraphy (RVG) imaging system. Orifice opening was done using Hyflex CM orifice opener and cleaning and shaping was done using 17% EDTA as lubricant and 4% Hyflex CM rotary file system with the following sequence: 20.04%, 25.04% and 30.04%. Normal saline was used to irrigate the root canals in between use of each file.

After that, canals were dried using paper points, obturated using gutta-percha and sealapex sealer utilising the single cone obturation technique, and coronally sealed using composite restoration. A Third CBCT scan was taken after obturation for postoperative CBCT analysis. It was done for both these groups with 1 mm sections to calculate pericervical dentin thickness extending up to 4 mm above CEJ and 4 mm below CEJ. It was determined as the shortest distance between the nearest adjacent root surface (B2) and the canal outline (A2).

Amount of dentin loss after access cavity preparation step and after obturation step was calculated by subtracting the post access opening CBCT values and post obturation CBCT values from the preoperative CBCT values from CBCT readings (mm) in mesial, lingual, facial and distal surfaces of teeth at levels of 1 mm, 2 mm, 3 mm, 4 mm above CEJ and at 1 mm, 2 mm, 3 mm, 4 mm below CEJ [Table/Fig-5,6]. Mean difference was calculated between two groups for the amount of dentin loss after each step as stated above.

Preparation of the samples for the fracture resistance analysis: The acrylic resin mould was made to mount the teeth samples 1 mm below CEJ for the comparative evaluation of fracture resistance of both the groups under universal testing machine. The dimensions of the acrylic block were 15× 15× 25 mm (Table/Fig 7).

Analysis of fracture resistance: The test specimens were placed on the platform of the universal testing machine and stainless steel rod with tip diameter of 1 mm was used to apply the compressive load parallel to the long axis of the tooth at the speed of 1 mm/min using Universal Testing Machine until fracture and fracture resistance was calculated in Newton (12) (Table/Fig 8).

Statistical Analysis

An Independent sample t-test was applied to calculate the amount of pericervical dentin loss post access opening and postobturation between the two groups by using Statistical Package for Social Sciences (SPSS) software version 20.0. In addition, the fracture resistance of the endodontically treated teeth under compressive load in Newton (N) was calculated between the two groups by performing independent sample t-test using SPSS software version 20.0. The level of significance was set at p-value <0.001.

Results

According to the findings of the study, incisal cavity design was a more conservative method of accessing maxillary central incisors. On comparison, group 1 had more amount of pericervical dentin loss amongst than group 2.

Comparison between group 1 and group 2 for the amount of pericervical dentin loss at the level of 1 mm to 4 mm below CEJ and 1 m to 4 mm below CEJ on facial, lingual, mesial and distal surfaces, following observations were recorded:

At the level of 1 mm above the CEJ post access opening and postobturation, the lingual surface showed statistically significant results with a p-value of <0.001 (Table/Fig 9). At the level of 2 mm above the CEJ post access opening and post obturation, the lingual surface showed statistically significant results with a p-value of <0.001 (Table/Fig 10). At the level of 3 mm above the CEJ post access opening and post obturation, the lingual surface showed statistically significant results with a p-value of <0.001 (Table/Fig 11). At the level of 4 mm above the CEJ post access opening and post obturation, the lingual surface and the distal surface showed statistically significant results with a p-value of <0.001 (Table/Fig 12). At the level of 1 mm, 2 mm, 3mm and 4 mm below the CEJ post access opening and post obturation, the results were not statistically significant on each surface (Table/Fig 13),(Table/Fig 14),(Table/Fig 15),(Table/Fig 16).

Among all the surfaces, pericervical dentin loss was more significant on the lingual surface in the conventional group as compared to conservative group.

Comparison of the fracture resistance between the two groups showed that compressive strength (load at fracture) was higher in group 2 (1136.75 N) as compared to group 1 (687.22 N) with a t-value of -9.373 and was statistically significant with a p-value of <0.001 (Table/Fig 17).

Discussion

The present study showed that the conservative access cavity design preserved more pericervical dentin compared to conventional access cavity design. Among all the surfaces, pericervical dentin loss was more pronounced on the lingual surface in the conventional group than in the conservative group. Higher Fracture resistance was observed in conservative access cavity designs compared to conventional access cavity designs under compressive load.

According to Clark D and Khademi J, failures of endodontically treated teeth occur not only as a result of chronic or acute apical lesions, but also as a result of structural impairment to the teeth (6). The dentin near the alveolar crest is known as pericervical dentin. This crucial zone extends 4 mm above and 4 mm apical to the CEJ. Although the root apex and the coronal third of the clinical crown can be excised and replaced prosthetically, the dentin around the alveolar crest is irreplaceable (14),(15),(16).

In the current study, intact maxillary central incisors were used to measure the fracture resistance under simulated occlusal force while being treated with various access cavity designs. Magne P and Belser U, determined the significance of the cingulum in the case of incisor access, where the conventional cingulum positioned endodontic access approach affects the conservation of pericervical dentin thickness (17). When the maxillary anterior teeth are functionally loaded, there are significant tensile stresses localized at the cingulum. When the pericervical dentin is damaged during conventional access at the cingulum, these stresses can lead to structural failure.

CBCT was used in the current study to determine the precise pericervical dentin thickness prior to and after endodontic access cavity preparation. The most essential characteristics of CBCT are its non-invasive nature and quantitative precision of samples analysis of images in three dimensions, reducing the possibility of a radiographic or photographic transfer error (8),(9).

The DOM was used in magnification to visualise through minimal invasive access cavity preparation, locate the root canal orifices whose access is not in a straight line, to locate any calcific obstructions, to minimise the risk of any procedural errors such as gouging and strip perforation, and to preserve more pericervical dentin (18).

According to Clark D and Khademi J, the conservative endodontic cavity (CEC) involves the preservation of the roof of pulp chamber and pericervical dentin (6). EndoGuide burs, also known as CK micro-endodontic burs by Clark D and Khademi J, were used in the current study to preserve pericervical dentin. As per Lenchner NH, EndoGuide burs are ideal for magnification driven endodontics (19). It increases visibility and control during endodontic exploration while locating canals. It provides precision guidance with its passive safe-ended tip and extended shank for efficient canal access, creating an ideal glide path for instrumentation and conserves pericervical dentin to preserve the strength of the tooth.

In the present study, Hyflex CM rotary file system was used to prepare the canals in both the groups as this Nitinol rotary instrument is machined from a CM wire (controlled memory), which provides self-centering ability, resistance to cyclic fatigue, flexibility, super elasticity, and control memory, reducing the risk of dentinal microcracks. Tziafas D et al., (20). proposed the review literature for the preparation prerequisites for effective irrigation of apical third of root canal which states that average diameters of apical constriction and apical foramen of cross sections of maxillary central incisors at 1mm from the apex ranges at 0.30 and 0.34 respectively. Hence, for better comparison and reproducibility, the sample teeth in both the groups were prepared to have an apical diameter #30 and 0.04 taper.

The current study found a significant loss of pericervical dentin in the mesial, distal, facial and lingual surfaces following access preparation in group 1 (conventional group) when compared to group 2 (conservative group). This difference is due to the use of the SS White Endoguide EG5 bur (Clarke-Khademi), which has a tapered round ended design that allows the formation of a complete funnel with the narrow portion of the funnel in the pericervical dentin zone, as compared to a conventional round endo access bur. (1) There was statistically significant difference observed between the two groups on lingual surface at the level of 1 mm, 2 mm, 3 mm and 4 mm incisal to CEJ. The significant results would be seen because conventional access cavity preparation was closer to the cingulum portion on the lingual surface of maxillary central incisor which might reduce more amount of pericervical dentin when compared to incisal approach in group 2. Among all the four surfaces, the lingual surface showed statistically significant difference between the two groups at 1 mm, 2 mm, 3 mm and 4 mm incisal to CEJ.

In a study done by Varghese VS et al., it was found that conventional access cavity preparation resulted in a significant loss of pericervical dentin in the mesial, distal, facial and lingual surfaces (10). Only the lingual and distal surfaces of group II (incisal access cavity) showed a significant loss of pericervical dentin when compared to the other two surfaces. The loss of pericervical dentin was greater in group I (conventional) than in group II (incisal).
Haralur SB et al., concluded that the remaining coronal tooth structure width contributes significantly towards the fracture strength of endodontically treated teeth which is in accordance with the present study (21). The researchers strongly suggest the self-supported coronal dentin improves the fracture resistance by favorable stress transmission to the root (22).

The results of the present study is in accordance with the previous studies performed by Makati D et al., (7), Varghese VS et al., (10) and Krishan R et al., (23) which shows that conventional access cavity preparation caused a considerable loss of tooth structure in the pericervical region as compared to incisal access cavity preparation and increased resistance to fracture in conservative group as compared to conventional group in incisors, premolars and molars.

Limitation(s)

Conservative access cavity designs are likely to benefit patients, but they present clinicians with the challenge of addressing all canals, debriding all pulp tissue from pulp horns, and avoiding procedural complications while lacking “convenience form.” Another limitation of this study is that it is in-vitro. The clinical situation differs in terms of force, angulation, and surrounding supporting tooth structure. Despite the fact that the study was conducted on healthy extracted natural teeth, the presence of invisible microcracks, changes in moisture content, functional age changes, and morphological changes of dentin and pulp are difficult to standardise.

Conclusion

Within the limitations of this in-vitro study, it was concluded that when compared to the conservative access cavity design group, conventional access cavity design resulted in a significant loss of tooth structure in the pericervical region. As a result, incisal cavity design is a more conservative approach to accessing maxillary central incisors. Under compressive load, pericervical dentin conservation provided greater fracture resistance in the conservative group than in the conventional group. Future research could be done on the impact of various access cavity preparation approaches on the ability to detect and negotiate the root canals, quality of chemomechanical debridement, obturation and postendodontic restorations before implementing this procedure into our standard clinical practice.

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DOI and Others

DOI: 10.7860/JCDR/2023/59873.17261

Date of Submission: Aug 27, 2022
Date of Peer Review: Oct 14, 2022
Date of Acceptance: Nov 16, 2022
Date of Publishing: Jan 01, 2023

AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? Yes
• Was informed consent obtained from the subjects involved in the study? No
• For any images presented appropriate consent has been obtained from the subjects. No

PLAGIARISM CHECKING METHODS:
• Plagiarism X-checker: Sep 05, 2022
• Manual Googling: Oct 13, 2022
• iThenticate Software: Nov 15, 2022 (18%)

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