Dominika
Gadamer
2018, group 13EVALUATION OF ENDODONTIC TREATMENT
PERFORMED BY THE UNDERGRADUATE
INTERNATIONAL STUDENTS OF LITHUANIAN
UNIVERSITY OF HEALTH SCIENCES: A PILOT STUDY
Master’sThesis
Supervisor Lekt. N.Skučaitė
LITHUANIAN UNIVERSITY OF HEALTH SCIENCES MEDICAL ACADEMY
FACULTY OF ODONTOLOGY
CLINIC OF DENTAL AND ORAL PATHOLOGY
EVALUATION OF ENDODONTIC TREATMENT PERFORMED BY THE UNDERGRADUATE INTERNATIONAL STUDENTS OF LITHUANIAN UNIVERSITY
OF HEALTH SCIENCES: A PILOT STUDY Master’s Thesis
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No. MT parts MT evaluation aspects
Compliance with MT requirements and evaluation Yes Partially No 1 Summary (0.5 point)
Is summary informative and in compliance with
the thesis content and requirements? 0.3 0.1 0 2 Are keywords in compliance with the thesis
essence? 0.2 0.1 0
3
Introduc-tion, aim and tasks (1 point)
Are the novelty, relevance and significance of the
work justified in the introduction of the thesis? 0.4 0.2 0 4 Are the problem, hypothesis, aim and tasks
formed clearly and properly? 0.4 0.2 0
5 Are the aim and tasks interrelated? 0.2 0.1 0
6
Review of literature (1.5 points)
Is the author’s familiarization with the works of
other authors sufficient? 0.4 0.2 0
7
Have the most relevant researches of the scientists discussed properly and are the most important results and conclusions presented?
0.6 0.3 0
8 Is the reviewed scientific literature related enough
to the topic analysed in the thesis? 0.2 0.1 0 9 Is the author’s ability to analyse and systemize the
scientific literature sufficient? 0.3 0.1 0 10
Material and methods (2 points)
Is the research methodology explained
comprehensively? Is it suitable to achieve the set aim?
0.6 0.3 0
11
Are the samples and groups of respondents formed and described properly? Were the selection criteria suitable?
0.6 0.3 0
12
Are other research materials and tools (questionnaires, drugs, reagents, equipment, etc.) described properly?
0.4 0.2 0
13
Are the statistical programmes used to analyse data, the formulas and criteria used to assess the level of statistical reliability described properly?
0.4 0.2 0
14
Results (2 points)
Do the research results answer to the set aim and
tasks comprehensively? 0.4 0.2 0
15 Does presentation of tables and pictures satisfy
the requirements? 0.4 0.2 0
16 Does information repeat in the tables, picture and
17 Is the statistical significance of data indicated? 0.4 0.2 0 18 Has the statistical analysis of data been carried out
properly? 0.4 0.2 0
19
Discussion (1.5 points)
Were the received results (their importance, drawbacks) and reliability of received results
assessed properly?
0.4 0.2 0
20 Was the relation of the received results with the
latest data of other researchers assessed properly? 0.4 0.2 0 21 Does author present the interpretation of results? 0.4 0.2 0
22 Do the data presented in other sections
(introduction, review of literature, results) repeat? 0 0.2 0.3 23
Conclu- sions (0.5 points)
Do the conclusions reflect the topic, aim and tasks
of the Master’s thesis? 0.2 0.1 0
24
Are the conclusions based on the analysed material? Do they correspond to the research results?
0.2 0.1 0
25 Are the conclusions clear and laconic? 0.1 0.1 0
26
References (1 point)
Is the references list formed according to the
requirements? 0.4 0.2 0
27
Are the links of the references to the text correct? Are the literature sources cited correctly and precisely?
0.2 0.1 0
28 Is the scientific level of references suitable for
Master’s thesis? 0.2 0.1 0
29
Do the cited sources not older than 10 years old form at least 70% of sources, and the not older than 5 years – at least 40%?
0.2 0.1 0
Additional sections, which may increase the collected number of points
30 Annexes Do the presented annexes help to understand the
analysed topic? +0.2 +0.1 0
31
Practical recommen-
dations
Are the practical recommendations suggested and
are they related to the received results? +0.4 +0.2 0 General requirements, non-compliance with which reduce the number of points 32
General require- ments
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15-20 pages (-2 points)
<15 pages (-5 points)
33 Is the thesis volume increased
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volumes of its structural parts balanced? -0.2 point -0.5 points
38 Amount of plagiarism in the thesis. >20%
(not evaluated) 39
Is the content (names of sections and sub-sections and enumeration of pages) in compliance with the thesis structure and aims?
40
Are the names of the thesis parts in compliance with the text? Are the titles of sections and sub-sections distinguished logically and correctly?
-0.2 point -0.5 points
41 Was the permit of the Bioethical
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42 Are there explanations of the key terms
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-0.2 point -0.5 points *In total (maximum 10 points):
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TABLE OF CONTENTS
SUMMARY ... 7
INTRODUCTION ... 8
1 REVIEW OF LITERATURE... 9
2 MATERIAL AND METHODS ... 15
3 RESULTS... 20
4 DISCUSSION ... 25
CONCLUSIONS ... 29
REFERENCES ... 30
Evaluation of endodontic treatment performed by the undergraduate international students of Lithuanian University of Health Sciences: a pilot study
SUMMARY
Background: Perception of endodontic treatment principles by undergraduate students could have impact on quality of root canal treatment in general practice.
Aim: The aim of this study was to evaluate the short-term outcome of endodontic treatment performed by international undergraduate students of Lithuanian University of Health Sciences and analyse the factors that could affect the root canal treatment based on the reports of those students. Material and methods: Twenty-five teeth treated by the 3rd and 4th year international students were analysed. NiTi rotary ProTaper instruments were used for preparation and cold lateral condensation technique for obturation of root canals. Follow up period was 6-8 months. Clinical symptoms, radiographic images, and restorations of treated teeth were evaluated. The questionnaire regarding obstacles and perception towards root canal treatment during the clinical course of endodontics was given for 21 4th year student.
Results: The short-term outcome of endodontic treatment provided by undergraduate students in 76% was evaluated as an acceptable. The location of filling material was adequate in 84% and satisfactory density only in 60% of the cases. Nine teeth at the time of the follow up had permanent restorations. The iatrogenic errors were detected in 12% of all teeth. The analysis of questionnaire showed that many students (38.1%) had problem with obtaining proper visualization.
Conclusions: The tendency of root canal treatment performed by the international undergraduate students of LUHS is acceptable. The biggest obstacle according to students’ opinion is obtaining proper visualization during endodontic treatment.
INTRODUCTION
Endodontic therapy is the best option for the teeth with infected pulp and/or periapical tissues in order to preserve the tooth and avoid extraction. The purpose of this treatment is to remove all the necrotic/inflamed pulp tissue, shape the root canal, remove the debris likewise apply sufficient disinfection protocol in order to remove microorganisms and place medicaments or obturation materials [1, 2]. The outcome of endodontic treatment depends on the operator’s ability to perform the treatment procedures without making any mistake. It is evident that even if endodontic therapy was successfully performed, its long-term outcome cannot be always predictable and depends on other factors such as pre-treatment dental status and post-treatment coronal restoration [3]. The assessment of the effectiveness of endodontic treatment is usually based on clinical symptoms and radiograph images recorded during the follow-up visit, compared to the situations before and during treatment [4].
Root canal therapy in many cases is performed not by specialist but by general practitioners who sometimes lack in basic knowledge and always need training of the newest endodontic techniques [5]. Thus the importance of clinical endodontic teaching and students’ perception towards endodontics should be highlighted [6-8]. European Society of Endodontology prepared Undergraduate Curriculum Guidelines for Endodontology [1] which directs universities on how to teach students and what criteria need to be fulfilled in order to successfully train future dentists. Clinic of Dental and Oral Pathology in Lithuanian University of Health Sciences (LUHS) established curriculum according to which every second year dentistry student undergoes preclinical course of endodontology. The aim of those classes is to learn techniques of root canal treatment (including hand and rotary shaping systems as well as different obturation techniques). Curriculum established lectures and laboratory training. Clinical course of endodontology continues during the sixth and seventh semesters. Students should learn to perform diagnostic and treatment procedures on patients. Third year students have to attend lectures also. At the end of this course they should be able to perform not complicated root canal treatment on single and multi-rooted teeth as well as perform easy retreatment cases which do not require intervention of the specialist with the microscope.
Poor quality of endodontic therapy in general practice is supposed to be due to lack of understanding of the treatment principles during university training [9]. Thus, the aim of this pilot study was to evaluate the short term outcome of endodontic treatment performed by the international undergraduate students of LUHS and analyse factors that could affect it.
1 REVIEW OF LITERATURE
1.1 Quality of endodontic treatment in other dental schools
There are some studies regarding quality of endodontic treatment provided by undergraduate students published in the scientific literature. Based on those studies, step-back technique using Stainless Steel hand files [10-18] and rotary Nickel-Titanium instruments [10, 12, 17-19] was used for shaping of root canals in dental schools from different countries. The lateral condensation was performed for root canal obturation by all undergraduate students. Disinfection protocol during chemo-mechanical preparation and type of restoration of endodontically treated teeth was not mentioned in most of the studies. In the researches, where disinfection was described, students in all cases were using sodium hypochlorite (NaClO) as an irrigation solution. However the concentration differed from 0.5% in the university in Serbia [17], through 2.5% in Sudan [19] and Saudi Arabia [11] to even 3% NaClO in Greece [16]. The quality of endodontic treatment provided by the undergraduate students was evaluated as an acceptable or unacceptable according to published studies [1, 20, 21] The acceptable endodontic treatment is based on the adequate density (homogenous, no voids present) of the filling material and adequate length (0-2 mm below the radiographic apex) of the root canal obturation [22]. Based on the results of published studies endodontic treatment provided by undergraduate students was estimated as an acceptable from 17,8% to 79,5% in various dental schools (Tab.1). Such a big discrepancy in the quality of endodontic treatment can be due to different criteria of evaluation and group of teeth predominant in the sample.
Authors from various countries, after assessing the quality of endodontic therapy carried out by the undergraduate students recommended some changes in the pre-clinical and clinical teaching curriculum. The proposed improvements were as follows: incorporation of new root canal treatment methods (Nickel-Titanium instruments, electronic apex locators), increase in training time and direct supervision of the specialist in order to improve the quality of the teaching and students’ perception [10-19, 22, 23]. Additionally, some researchers suggested that schooling should focus more on the importance of canal preflaring [16] and coronal sealing [13].
Table 1. Evaluation of endodontic treatment carried out by undergraduate students in various countries.
Authors Country Acceptable treatment (%)
Unal G.C. et al. [23], 2011 Turkey 79.47
Elsayed R.O. et al. [19], 2011 Sudan 24.2
AlRahabi M.K. [11], 2017 Saudi Arabia 68.9
Kumar M. et al. [12], 2018 Ireland 49 (single-rooted) 17 (multi-rooted)
Kelbauskas E. et al. [10], 2009 Lithuania 84.1 adequate filling location 79.5 good radiodensity Mostert V.C.; et al. [13], 2018 South Africa 52.27
Smadi L.et al. [14], 2015 Jordan 29.2
Ehsani M.et al. [15], 2014 Iran 17.8
Khabbaz M.G et al. [16], 2010 Greece 54.8
Vukadinov T. et al. [17], 2013 Serbia 74.22
89.73 adequate filling location 92.6 good radiodensity
Rapo H et al. [18], 2017 Finland 65.7
The outcome of root canal therapy cannot be predicted instantly after the treatment. It depends not only on the quality of canal shaping and obturating but also on maintaining sterile environment by mean of isolating of the treated tooth with the rubber dam system, adequate irrigation, canal disinfection, coronal post-treatment restoration sealing and pre-treatment periapical condition [24-27]. The outcome of the endodontic treatment was analysed in one [18] of the published studies regarding the treatment provided by the undergraduate students. Status of periapical tissues, root canal filling location, density, shaping technique and type of crown restoration were evaluated. The
overall results of the follow up, conducted from 5 months up to almost 3 years after the endodontic therapy, were acceptable. The level of the root canal fillings with the adequate quality and healing of periapical tissues was established in 65.7% and 87.6% of the cases respectively. Teeth with the highest number of failed treatments were maxillary and mandibular molars. The most frequent error was over-instrumentation, nevertheless, 73.3% of all those cases showed healing. Most of the teeth (84.31%) treated with Nickel-Titanium rotary instruments demonstrated excellent endodontic therapy outcome [21].
1.2 Quality guidelines for endodontic treatment
The latest quality guideline for root canal treatment established by the European Society of Endodontology was published in the 2006th year [20]. This document is focused on two aspects- how to choose the most suitable treatment plan and the quality or level of performed treatment. The importance of patient’s anamnesis, clinical examination (extra- and intra-oral) and proper diagnosis is strongly highlighted. While choosing any of the therapy methods, such as vital pulp management, root canal or surgical treatment, all dentists should follow indications and contra-indications included in this article. As for the legal issues, all treatment records and informed consent should be kept in the clinical documentation. Continuing, management of the vital pulp can be performed in a manner of indirect or direct pulp capping if the practitioner diagnosed the tooth with reversible pulp damage. Pulp amputation or pulpectomy is indicated for irreversible changes in the pulp tissue, depending on the root formation state, level of the inflammation and future prosthetic plan. Non-vital or extirpated pulp is managed by root canal treatment. The preoperative radiograph and the need of anaesthesia should be evaluated before the procedure. Isolation of the tooth is achieved with the use of rubber dam and access cavity is prepared. Determination of the working length should be established using electronic and radiographic methods together. Afterward, shaping is carried out to “remove remaining pulp tissue, eliminate microorganisms, remove debris and shape the root canal(s)” [20]. The irrigation, which should be done between each instrument, ideally has to have disinfection and debris dissolving properties. Inter-appointment intra-canal medications are rarely necessary. Filling of the root canal aims to seal not only the apical part but dentinal tubules and accessory canals as well. However, to achieve complete canal isolation, proper restoration with good marginal integrity has to be placed over the tooth to avoid microleakage and/or tooth fracture. If there is any difficulty or approaching the canal in the described manner is impossible, surgical endodontics is performed. It can be done by incision and drainage, apical operation or other endodontic surgical methods. Exploratory surgery, peri-radicular curettage, biopsy, root-end resection or root-end preparation and filling are the types of apical surgery. When it comes to other
methods, it can be reparation of the perforation and root or tooth resection. When root canal treatment either failed is impossible to perform or surgical endodontics cannot be executed, extraction with replantation is recommended. When there is no pain or other patient’s complains, intra-oral and radiographic examination revealed no pathological changes and in case of pre-treatment periapical lesion its size has decreased or is completely absent, it is concluded that the treatment was successful. Nonetheless, if such lesion will still appear after 4 years, this might be identified as post-treatment disease. Any other signs or symptoms would mean that the treatment had an unfavourable outcome.
The recommendations regarding radiographic examination after root canal treatment differs according to authors [28]. The European Society of Endodontology recommends reviewing the therapy outcome after 1 year and should be periodically repeated until the complete tissue healing or at least up to 4 years after the treatment [20]. Chng et al. (2004) recommends reviewing the therapy outcome after 6 months until complete heal of the tissues occurs. Chinese Stomatology Association (2015) suggested that apical radiographs can be taken at 3, 6, 12 or 24 months after the treatment [29]. Association of Endodontists and American Academy of Oral and Maxillofacial Radiology (2015) did not state any timescale for conducting follow up, however, it was suggested to use cone beam CT scan for obtaining better treatment results [30].
1.3 Students attitude towards teaching program of Endodontology
Shetty N. et al. distributed questionnaire among three dental colleges in India [31]. Its aim was to evaluate undergraduate students’ perception and attitude towards endodontics as a specialty. Most (93%) of the respondents suggested that incorporation of educational aids, for instance, 3D models, would have a great impact on their preclinical study and self-confidence level. However, 70.6% felt already comfortable to perform root canal treatment after preclinical training on extracted teeth. About half (46.5%) stated that the third grade is the best time to begin endodontic training.
A similar study was conducted in New Zealand [32]. According to the results, the fourth year students treated on average 2.6 canals. When the fifth year novices were asked about the amount of treated canals that would make them feel more confident, theiranswer varied from 4 to 22. More than half (70,7%) of all the students, did not experience any difficulties during root canal treatment. The biggest obstacles, especially for the higher course students, were related with root morphology (multiple canals or calcification). A lot of the undergraduate students assumed that more preclinical training hours would be helpful for their confidence and skills level.
Work on the artificial teeth revealed the lesser amount of iatrogenic errors if compared to the work on extracted human teeth during the pre-clinical course, according to the study provided by Tchorz J. P. et al. [33]. Such tendency could be due to unpredictable and complex root canal morphology in the natural extracted teeth. According to the authors, training on the artificial teeth might have no impact on the clinical work as shown in the research, but will help with better understanding of the entire procedure and practice their skills before performing the treatment on more complex root canals in human teeth.
1.4 Most frequent mistakes of endodontic treatment inpractice
In dental clinics, the most common iatrogenic error while carrying out the root canal treatment is obturation procedure according to published studies (Table 2). Not adequate radiodensity was found in 21.9% up to 42.7% of cases in different publications [34, 35, 36]. The location of the filling material was not adequate in many cases (18.9%-56.8%) as well [34-35, 38, 39]. The lower frequency of mistakes, but still substantial, was associated with canal shaping. Predominant was ledge formation (26%) [34] and apical perforation (25.9%) [36]. These studies revealed rather a poor outcome. Most of the dentists got their knowledge and treatment habits of endodontics from the university training. Thus, it is of great importance to focus more on teaching students.
Table 2.Most frequent iatrogenic errors.
Authors Country Frequency of iatrogenic errors
Mozayeni M. A. et al. [34], 2006 Iran 27.3% not adequate radiodensity 26% ledges
23.3% under-filled canals Haji-Hassani N. et al. [35], 2015 Iran 42.7% not adequate radiodensity
18.9% over-filled canals
17.2% errors during instrumentation (ledge/ transportation/ strip perforation/ broken
instrument/ apical perforation) Yousuf W. et al. [39], 2015 Pakistan 22.7% over-filled canals
8.9% under-filled canals 0.9% broken instruments 0.4% apical transportations Akhtar S. A. et al. [37], 2016 Saudi Arabia 12% apical transportations
10% ledges 5% strip perforations 5% apical perforations 4% broken instruments Adebayo E. T. et al. [38], 2012 Nigeria 21% under-filled canals 8% over-filled canals Schulte A. et al. [36], 1998 Germany Group A: radiographs from 1983
55.2% under-filled canals 25% not adequate radiodensity
23.9% apical perforation
Group B: radiographs from 1992
56.8% under-filled canals 21.9% not adequate radiodensity
25.9% apical perforation
2 MATERIAL AND METHODS
The study was approved by the Bioethics Center of the Lithuanian University of Health Science, Kaunas (Protocol No. BEC-OF-84) (Annex 1).
2.1 Follow-up material and methods
The study included patients treated by the international students of the 6th and 7th semesters at LUHS in 2017. The patients were chosen according to the inclusion/exclusion criteria (Tab.3). Initially, 39 patients were analysed. Twenty-one of them did not meet inclusion criteria: 8 patients refused to conduct follow up, 2 moved away from Kaunas, 8 were unreachable (no contact) and in 3 cases radiographic documentation was not clear. In total, 18 patients were included in this research with 25 treated teeth (39 canals).
The patients were given a short introduction, orally and in written form, about the purpose of the research and were then asked to sign a written consent (Annex 2). All of them were treated endodontically by the under-graduate 3rd and 4th year students (2016/2017) of LUHS with the supervision of the endodontist. The treatment has been carried out after establishing the diagnosis according to anamnesis, clinical and radiological examination. . All evaluated canals were instrumented in a crown-down manner with ProTaper Universal (Dentsply Maillefer)or ProTaper Next (Dentsply Maillefer) rotary system driven by the endodontic micro-motor control unit WAVEONE™ (DentsplyMaillefer). Working length was determined with the use of the Precise Apex Locator Compact PAL (Lumen, Lithuania) and radiographic evaluation when Stainless-Steel K-file (Dentsply Maillefer)was placed inside the canal. Between each file 0.5% NaClO solution was used as an irrigant and canals were passed with a small size K-file to ensure patency. Disinfection prior to filling the canals was achieved by combining 0.5% NaClOand 3% EDTA. Obturation was performed with the cold lateral condensation technique. Canals were obturated with Standard or ProTaper gutta-percha cones (DiaDent and Dentsply Maillefer respectively) and accessory points until the spreader (ISO size 20 or 25) (Dentsply Maillefer) could not be placed into the canal anymore. The excess of the gutta-percha was removed with the heated hand instrument and access cavity was cleaned from any remains of the sealer overflow. In case of multi-visit treatment, the cotton was placed over the canal orifices and temporary filling (zinc oxide eugenol cement or Coltosol F) was placed. In some teeth, students entered the non-setting calcium hydroxide paste into the canal as a medicament, which is known due to its antimicrobial property.
Table 3.Inclusive and exclusive criteria for patients conducted in the study.
Exclusion criteria Inclusive criteria
Not attending follow up due to: - no contact,
- health problems, - moved away or - unknown reason.
Patient was willing to undergo radiographic and clinical examination.
Patient was under 18 years old. Patient was above 18 years old. Not all treatment steps were performed by
international students of LUHS:
- patient was sent to the specialist to continue treatment or
- patient didn’t continue root canal treatment due to personal reasons.
All treatment steps were performed by international students of LUHS.
One or more of the radiographic images were missing:
- pre-operative radiograph, - intra-operative radiograph, - post-operative radiograph.
Full radiographic documentation was accessible - pre-operative radiograph,
- intra-operative radiograph and - post-operative radiograph.
Poor radiograph quality, not clear image at any level of the treatment, superimposing or not clear apex visibility.
Good radiograph quality with clear image.
Any doubt about treatment outcome. No doubt concerning the treatment outcome.
The analysis of the endodontic treatment quality was based on combination of the criteria published in several articles and ESE (European Society of Endodontology) guideline [14,
20,40,41] (Tab.4). To avoid misinterpretation of the iatrogenic errors, ledge was not included in this research due to its hard recognition on the radiographic image. The timing of the follow-up was from 6 up to 8 months after root canal treatment. During anamnesis, questions concerning patients’ perception of the treated tooth and surrounding tissues were asked. Intra- and extra-oral
examinations were carried out to assess the presence of pain, reaction to percussion and palpation, swelling, sinus tract or any other pathologic changes in the tooth and its adjacent structures. The type of the tooth restoration was evaluated.
Table 4.Criteria for the evaluation of root canal treatment quality.
Parameter Criteria Definition
Location of root canal filling (Annex 4-5)
Adequate Filling 0-2 mm below the radiographic apex.
Under-filled Filling more than 2 mm below the radiographic apex. Over-filled Filling extruded beyond the radiographic apex. Filling density
(Annex 7-8)
Adequate Homogenous filling with no voids present. Not adequate Poor homogeneity with the presence of voids. Iatrogenic
error
(Annex 9-12)
Transportation The filling material located on the outer curvature of the canal at the apical third.
Furcation perforation
Obturation material extruded through the furcation area and radiographically detected in multi-rooted teeth.
Strip perforation Obturation material extruded in the lateral (inner) wall of both buccal roots of maxillary molars, mesial and distal roots of mandibular molars, and in any root of other teeth.
Root perforation Obturation material extruded in any area of a root except the furcation area in multi-rooted teeth.
Fractured instrument
Radiopaque fractured instrument segment was detected in the root canal or extended into the periapical area in X-ray radiographs.
Wrong diagnosis
Failure in obtaining the right diagnosis; wrong differential diagnosis.
Clinical symptoms
Absent No symptoms.
Present Presence of: discomfort, sensitivity, pain, swelling, fistula and/or increased mobility.
Coronal sealing Adequate Good retention and marginal seal.
Not adequate Visual, probed or radiographic evidence of coronal discrepancy with or without exposure of canal filling into the oral cavity.
Adequate No evidence of microleakage or any coronal discrepancy.
The criteria for the assessment of the root canal treatment outcome, according to ESE recommendations were applied in this study (Tab.5) [20]. Not strict criteria were applied due to evaluation of the short term outcome of the endodontic treatment in this study.
Table 5.Criteria for the assessment of the root canal treatment outcome[20]. Treatment
outcome
Strict criteria Not strict criteria
Successful Complete absence of periapical
radiolucency.
There might be some periapical radiolucency (depends on pre-treatment
situation).
Good coronal seal. Coronal sealing not taken into the consideration
Adequate filling location, density, adequate shaping, no iatrogenic errors
or patient complains.
Adequate filling location, density, no iatrogenic errors or patient complains.
Unsuccessful The presence of any errors:
under-/over-filling, poor density, inadequate shaping, iatrogenic error(s), patient
complains.
The presence of any errors: under-/over-filling, poor density, inadequate
shaping, iatrogenic error(s), patient complains.
2.2 Questionnaire material and methods
To understand the background of problems faced by students during endodontic therapy the questionnaire was conducted. All the (21) international undergraduate students of the 4th grade (2017th year) from Faculty of Odontology, LUHS, who performed root canal treatment on the patients were given the survey (Annex 3). The rest of the students who did not participate either did not continue studies during the 7th semester or were absent due to Erasmus program. The questionnaire consisted of 15 questions in total, 11 of them had multiple choice answers and the remaining 4 were open questions. Students were asked about their endodontic experience, the number of treated canals, shaping and obturation methods used predominantly and their perception towards root canal treatment. Other questions focused on the most problematic steps students confronted during the endodontic procedure and their awareness of possible mistake that they could have made either during access opening, shaping, obturating or placing temporary filling between the visits.
2.3 Statistical analysis of the data
The outcomes of conducted follow up and questionnaire were analysed in a numeric manner. The study results were analysed with the use of the statistical program IBM SPSS 23. For the nominal values, to analyse the relationship between them, whereby it was possible to check if there is a difference between groups which are compared or a relation between two nominal variables, Chi-square test was run. To compare quantitative variables in groups Mann-Whitney test was used because of the small samples. The difference between groups or relation between variables was significant if p-value <0.05. Diagnostic reliability of assessors was evaluated by applying Cohen’s kappa coefficient. The strength between two nominal variables in the sample was estimated using Cramer’s coefficient. However, this pilot study shows only the tendency and the results cannot be reliable because of the small samples.
3 RESULTS
3.1 Follow-up results
Since the total number of patients included in this study has been limited, displayed results cannot be entirely reliable and will show only the tendency. Digital radiograms of 18 patients were reviewed. Examination involved 25 teeth. The distribution of teeth treated by the undergraduate students is shown in Figure 1. Repeatability of the data collected by two investigators was evaluated by Kappa coefficient. When evaluating pathology of periapical tissues, localization and density of root canal filling material high enough (k=0.92) Kappa coefficient was estimated.
Fig. 1. The most frequent group of teeth included in this study.
Only 9 out of 25 teeth the time of the follow up had permanent restorations. Most of the patients were still waiting in the queue for the prosthetic treatment. Diagnosis of periodontitis apicalis chronica was estimated before the treatment for most (44%) of the evaluated teeth (Tab.6). Table 6. The prevalence of the pre-treatment diagnosis.
Diagnosis Frequency (%)
Pulpavitalis 4 (16.0)
Pulpitis asymtomatica 5 (20.0) Pulpitis symptomatica 5 (20.0) Periodontitis apicalischronica 11 (44.0)
The location of root canal filling in most of the analysed cases (84%) was adequate. (Tab.7). The whole length of the root canal filling was searched for the voids visible on the radiograph. Any radiolucent area indicated not adequate density, which appeared in 40% of all cases. Only 12% of all cases had an iatrogenic error (Tab.7).The increasing tendency for the value of iatrogenic error with respect to root canal curvature was estimated (Tab.8). No significant difference between mean
Incisor 40% Canine 12% Premolar 28% Molar 20%
Frequency of group of teeth included in this study
values of iatrogenic error with respect to system of instruments (ProTaper Next or Universal) used for root canal shaping was found.
Table 7. Location, density of the root canal filling and iatrogenic error analysed on the radiograph straight after the treatment.
Criteria Radiographic appearance Frequency (%)
Filling location Adequate 21 (84)
Under-filled 3 (12)
Over-filled 1 (4)
Filling density Adequate 15 (60)
Not adequate 10 (40)
Iatrogenic error Present 3 (12)
Absent 22 (88)
The general outcome of 76% of the root canal treatments during the time of the follow up was acceptable (Fig.2). Two out of 18 patients had their teeth already extracted by the time of 6 months after the treatments were performed. We have no dental radiographic examination of these patients, only anamnesis and clinical evaluation of tissues after the tooth extraction. One out of the 18 patients came with the complaints of the pain in the area where root canal treatment was performed but radiographic examination revealed no pathological changes in the tissues surrounding the treated tooth. With the further examination, it was found that there was a deep caries lesion in the adjacent tooth, what was causing the discomfort. Two other patients were sent for the retreatment due to pathological changes in surrounding tissues.
Distribution of the treatment outcome with respect to pre-operative periapical lesion is shown in Table 9. Although results of endodontic treatment outcome according to pathology of periapical tissues results did not differ significantly (p>0.05), in cases where a periapical lesion was estimated before the treatment it was a tendency for failure.
Acceptable Not acceptable
Percent (%) 76 24
0 50 100
Root canal treatment outcome
Fig. 2. Follow up treatment outcome results according to not strict criteria. Table 8. Distribution of iatrogenic error with respect to root canal curvature.
Canal curvature Straight Frequency (%) Moderate Frequency (%) Severe Frequency (%)
Iatrogenic error Present 0a(0) 2a, b(25) 1b(100)
Absent 16a(100) 6a, b (75) 0b(0)
Table 9. Distribution of treatment outcome according to the existence of pre-operative periapical lesion.
Pre-operative lesion
Yes No
Frequency (%) Frequency (%)
Treatment outcome Acceptable 7a (63.6) 12a (85.7)
Not acceptable 4a (36.4) 2a (14.3)
3.2 Questionnaire results
The statistical analysis of the questionnaire showed that half of the students treated not more and not less than at least 5 endodontic cases during 6th and 7th semester in total and molars (38.1%) were the most often group of treated teeth (Fig.3).
Fig. 3.Distribution of teeth students were working on. Incisors 24% Canines 9% Premolars 29% Molars 38%
Distribution of teeth students were working on
The biggest obstacle for the students while performing endodontic treatment was shaping and canal obturation (Tab.10). Distribution of the answers concerning students’ awareness of their mistakes is shown inTable11. The frequency of iatrogenic errors was not related to the number of canals students treated until the time of the follow-up.
Table 10.The most problematic step for students performing root canal treatment. Frequency (%)
Step Obtaining proper visualization 8 (38.1)
Shaping/obturation problems 13 (61.9)
Table 11.Students’ awareness of their mistakes.
Frequency (%)
Mistake Not adequate filling location or poor condensation 12 (57.1)
Ledge or perforation 8 (38.1)
Forgot to seal the orifices with cotton before placing temporary
1 (4.8)
No tendency was found between type of the shaping system used and iatrogenic mistakes. However, there was an increased tendency for not adequate filling location or poor condensation when students used ProTaper gutta-percha cones (Tab.12). Problems with shaping and/or obturating the canal led to not adequate filling location or poor condensation in most cases. As a consequence of the difficulty with obtaining proper visualization, 62.5% of the students had the propensity to perform ledge or perforation (Tab.13). In most of the cases (47.6%) students placed temporary filling after the endodontic treatment and only 23.8% restored the tooth with the permanent restoration (Tab. 14).
Table 12. Distribution between type of shaping system and gutta-percha and the iatrogenic errors.
Mistakes Shaping system mostly used
Frequency (%)
Type of gutta-percha cone Frequency (%) Rotary Protaper Next instruments Rotary Protaper Universal instruments Hand K-files Standard Gutta-percha cones ProTaper Gutta-percha cones Not adequate filling location or poor condensation 4a 7a 1a 6a 6a (57,1) (58.3) (100) (50.0%) (75.0%) Ledge or perforation 3a 5a 0a 6a 2a (42.9) (41.7) (0.0) (50.0%) (25.0%)
Table 13. Distribution between problem students faced during root canal treatment and mistakes.
Mistakes Problem
Obtaining proper visualization
Shaping/obturation problems Not adequate filling
location or poor condensation
Frequency (%) 3a (37.5) 9a (75.0)
Ledge or perforation Frequency (%) 5a (62.5) 3a (25.0)
Table 14.Type of restoration performed after the root canal treatment.
Frequency (%)
Restoration Temporary filling and referral for prosthodontic treatment 6 (28.6)
Temporary filling 10 (47.6)
Permanent filling 5 (23.8)
4 DISCUSSION
Root canal therapy is a complex process. Knowledge of possible errors is of great importance for the dentistry practitioners in order to avoid a failure. The transition from the pre-clinical to clinical course might be very stressful and problematic for many students. Not only lack of the experience, but in the case of international students, a language barrier could influence the treatment outcome by increasing the level of stress and misunderstandings. A study conducted by Estrela C. et al. [3] revealed that human error, such as stress, bad frame of mind, personal problems or simply lack of focus and fatigue, should be taken in consideration while evaluating the treatment outcome.
This pilot study shows only the tendency of students' mistakes and perceptions. The results cannot be reliable because of the small samples. However, it would be of interest to find out in the future how many from all of the LUHS students succeed or failed to perform endodontic treatment and what were their main mistakes or obstacles. Furthermore, it is very important to note that patients with serious iatrogenic errors, such as broken instrument or furcation perforation, did not undergo follow up because they continued the treatment with the specialist with more experience and a microscope, thus their documentation was not accessible. Many of the patients who were participating in this study did not undergo prosthodontics treatment therapy despite the dentist’s recommendation and 16 of them had temporary fillings. The reason of this was lack of time or money. Students need to be more aware of the importance of the coronal seal and its influence on the overall outcome of root canal therapy [22-25]. Due to AAE recommendations “A minimum of four millimeters of material thickness provide an adequate seal. Based on current evidence, this seal can be expected to remain effective no longer than three weeks. Allowing a temporary material to remain longer than this period is an invitation to coronal leakage and future failure.” [42]. For such patients, simple composite restorations were made without placing post into the canal(s). However, this solution increases the risk of the vertical fracture of the tooth in future [42]. For the rest of the patients who were waiting for the prosthetic restorative treatment, post and core will be placed into the canal followed by the crown cementation. It means that at least half of the root canal filling will be removed. Therefore, if there were no complaints from the patient, the follow up was classified as acceptable even if the density of the filling was not adequate in the middle or coronal third. Some authors’ claim that the periapical tissue healing can take up to 10 years [37], thus complete healing did not occur in most cases. However, there was a tendency for the treatment failure when the lesion was detected prior the root canal therapy. Disregard some mistakes and the lack of the experience, the overall success rate of this research was at the acceptable level of 76%.The biggest obstacle for the students while performing endodontic treatment was shaping and canal obturation
(Tab.19). In most cases, it might be a result of the problem in obtaining the proper visualization or simply lack of clinical practice and experience. There was also noted increased tendency for the ledge in curved canals than in the straight ones. Canal curvature was evaluated and classified according to Schneider’s classification into straight, moderate or severe curved ones. Conforming to this, “ïf the angle is less than 5°, the canal is straight; if the angle is 5‑20°, the canal is moderately curved; and if the angle is greater than 20°, the canal is classified as a severely curved canal” [43]. In the 2009th, Kelbauskas E. et al. [10] conducted similar research and obtained higher
results(84.1%). The outcome might be slightly different between these two studies because of various samples sizes. However, the success tendency of the undergraduate LUHS treatments was better compared to the other universities. Ehsani M.et al. [15] achieved very poor (17.8%) success rate of the endodontic therapy. Some authors took in consideration not only density and location of root canal filling but also taper of root canal shaping, which had to be continuous, without any disturbances and following the original shape of the canal to be acceptable [13-15, 19]. Furthermore, not all of the universities were equipped with the electronic apex locators for working length determination [11, 13, 19]. This shows that the deficiency of electronic apex locators, while determining the working length, can have a great impact on the treatment outcome. This could be the reason of inadequate filling location when compared with the other studies where apex locators in combination with radiographic images for confirmation of working length were used [17]. Therefore, it is certain that some complications can be avoided using the modern technologies introduced to endodontics [44]. However, the treatment choice depends likewise on dental equipment, skills, and knowledge, amount of tooth structure left, patient's willingness to follow the instructions, desire and economic status of the individual. The group of teeth which was prevalent in the samples of different studies could be another reason for the difference in the research results. For instance, in study conducted in Turkey [23] where almost 80% of the treatment provided by undergraduate students was estimated as acceptable, 90.1% of clinical cases included the anterior teeth. On the contrary, molars showed the biggest number of completed endodontic treatment (42.5%) in the study provided at the university in Greece [16]. Nevertheless, these teeth presented the highest error frequency (60.7% were not acceptable and only 39.3% - acceptable). Similar results were obtained in Finland [18], Saudi Arabia [11] and Jordan [14], where teeth with the most not acceptable treatments were molars. However, study executed in Lithuanian University of Health Sciences [10] revealed no difference between the root canal fillings of single and multi-rooted teeth. The different pre-treatment dental status could be another cause of the discrepancy between the results of different studies Teeth without pre-operative pathology of periapical tissues showed higher healing rate (96.7%) when compared the ones where apical periodontitis was diagnosed
(84%) [18]. The most common iatrogenic error performed by undergraduate students from different universities occurred during canal obturation. Under-filled canals were found in 17.8% - 49.9% of all cases with the failure followed by poor condensation (36%) [11, 15, 16]. Most of the teeth with not adequate root filling location were molars [28]. The occurrence of mistakes at the time of root canal shaping estimated by different authors was as follows: ledge formation in 2.8% up to 17.5% out of all cases, apical transportation in 0.3%-10.2% and root perforation varied from 3.69% to 1.9% [14, 16, 17]. The fifth year students showed higher number of foramen perforation than the fourth course, but the frequency of root perforation was lower in the upper course practitioners [16]. It could be speculated that the higher year practitioners are given more complicated cases with bigger probability of making a mistake. Nevertheless, other research revealed that there is no statistical difference in the quality of root canal fillings between the fourth and fifth year students [14]. Isolation of the tooth during endodontic treatment is also an important factor for the treatment outcome. Teeth treated without rubber dam isolation demonstrated lower frequency healing rate (75%) in comparison with the isolated ones (92.1%), according to study provided in Finland [1 8]. What kind of perforation?? In the study conducted by Kwak S. W. et al. students’ preference was investigated towards various shaping instruments. The majority have chosen reciprocal WaveOne over rotary ProTaper Universal system (n=55 versus n=22 respectively), however ProTaper got higher flexibility and safety feeling scores [45]. Machine driven instruments were superior over Stainless Steel hand files. The most common iatrogenic mistake was ledge, which occurred in 37.7% of all cases and from that 94.1% happened while preparing the canal with the hand files. The overall treatment time required was significantly longer for hand instruments rather than rotary [21]. The follow-up timing is very crucial. It can not only reveal the failed therapy, and thus preserving the tooth from extraction by performing retreatment or endodontic surgery, but also can save a patient from suffering. The guidelines [29] recommend different time intervals. European Society of Endodontology suggests waiting 1 year, or once there are symptoms, to conduct a radiographic examination. However, the recommendations to make follow up after 6 months exists according to some authors, for instance Chinese Stomatology Association [29]. Thus, these norms, the fact that the treatment was carried out by novices (higher prevalence of errors) and the patient factor (unwillingness to be exposed to radiation or lack of time) contributed to the decision that the follow-up in this study was carried out 6-8 months after the completion of treatment.
Comparing the results from all included in this research studies; the iatrogenic error tendency could be spotted. The most common failure was during root canal filling. There are comparable frequencies intervals, between undergraduate and general practitioners, of inadequate filling
locations (17.8%-49.9% and 18.9%-56.8% respectively) and radiodensity (36% and 21.9%-42.7%) [10-19, 23, 34-39]. It should be very disquieting how similar success rate was obtained by the novices and general dentists. To improve those results, the undergraduate training programs should be improved, likewise, philosophy of through-life learning should be taught. The idea of advancement of the teaching program could be also incorporated at the LUHS. Even though, the results were acceptable, there was some tendency in errors. The changes can be done by introducing artificial training models, resin blocks, increasing teacher-student ratio, extending preclinical working and clinical observation/assisting time and the amount of seminars, so that the students can gain even more theoretical knowledge before starting the clinical course. According to the survey, many undergraduate students had a problem with obtaining proper visualization while performing root canal treatment on the patient, which is why more attention should be paid to this aspect of the training.
4.1 Limitations
As this is a pilot study and only shows the tendency, not the reliable results, it would be very interesting to carry out more extensive research in the future in order to obtain more predictable outcomes. Knowledge about the limitations of this research has encountered may help to introduce some improvements in a further research. The biggest obstacle was a small sample number due to exclusive criteria and patients’ factor (no number in patient’s card, unwillingness to be exposed on radiation, lack of time). It is evident, that most reliable results evaluating outcomes would be obtained with the use of cone beam computed tomography (CBCT) and histological samples [30]. The radiographs were not always taken at the same angle and could be not exactly evaluated. Otherwise analysis of dental radiographs and clinical investigation are usually used methods for follow up in clinical practice.
4.2 Acknowledgment
I wish to acknowledge Lekt. J. Tomkevičiūtė in the statistical analysis and by the students of LUHS who participated in the survey and handed over the information about their patients.
4.3 Conflict of interests
The author has not encountered any conflict of interests.
CONCLUSIONS
1. The tendency of root canal treatment performed by the international undergraduate students of LUHS is acceptable.
2. The biggest obstacle according to students’ opinion is obtaining proper visualization during endodontic treatment
3. The root canal shaping and obturation procedures induce highest prevalence of iatrogenic errors.
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ANNEXES
Annex 1: Bioethical approval.
Annex 2: Written consent in Lithuanian.
INFORMUOTO SUTIKIMO FORMA
Sutinku dalyvauti LSMU, Odontologijos fakulteto studentės, Dominika Gadamer, vykdomame tyrime, kurio tikslas- nustatyti LSMU Odontologijos fakulteto 3-4 kursų užsienio student atlikto endodontinio gydymo sėkmę ir išaiškinti galimas klaidas, įvykusias gydymo metu. Endodontinį gydymą studentai atliko prižūrimi dėstytojų Dantų ir burnos ligų klinikoje, LSMU ligoninėje, Kauno klinikose.
Tiriamasis_______________________________________________________________________
(Vardas, Pavarde) (Parašas)
Nr.:____________________ Data: _____________________
Annex 3: Endodontic questionnaire.
Endodontic questionnaire 1. Which semester are You studying now? ………
2. How many endodontic cases did you treat so far? ……… 3. How many canals did you treat?
a. During 6th semester ……… b. During 7th semester ………
4. Have You ever used the help of postgraduate student (microscope)? a. Yes
b. No
5. Did You do the follow up for any of Your patients after endodontic treatment? a. Yes
b. No
6. Which tooth group you worked on the most (circle your choice)? a. Incisors: upper / lower
b. Canines: upper / lower c. Premolars: upper / lower d. Molars: upper / lower
7. Which aspect of endodontic treatment did You find the hardest to achieve (circle your choice, can be several)?
a. Placing rubber dam b. Proper access opening c. Finding the orifices
d. Obtaining proper illumination & visual e. Working length determination
f. Mechanical shaping of canal g. Adequate irrigation
h. Obturation of the canal i. Effective anesthesia
8. What restoration type did you perform after root canal treatment? a. Temporary filling
b. Temporary filling and referral for prosthodontic treatment (post & core + crown) c. Permanent filling
d. Permanent filling and referral for prosthodontic treatment (post & core + crown)
9. What root canal shaping system did you mostly use? a. Hand instruments
b. Rotary instruments
i. Protapers Universal ii. Protapers Next
10. Which gutta-percha cones did You mostly use in lateral condensation technique? a. Protaper gutta-percha cones + accessories
b. Standard gutta-percha cones + accessories
11. Did You use any magnification method (loupes) while You were working on canals? a. Yes, always
b. Yes, but only in some cases c. No
12. Did You use rubber dam isolation system in all of Your cases? a. Yes
b. No
13. How many x-rays do You usually take for 1 endodontic treatment case? ………….. 14. Did You have any cases of retreatment? If yes, how many canals?
a. Yes, ……… b. No
15. Are You aware of any mistake that You did during endodontic treatment? What was it?
a. Perforation (crown, floor, zip, root, apical transportation..) b. Ledge c. Missed canal d. Broken instrument e. Wrong WL f. Over-obturation g. Short obturation
h. Forgot to seal the orifices with cotton before placing temporary i. Bad lateral condensation
Thank You for Your time
Annex 4: Example of the radiographic image classified as with the adequate filling location.
Annex 5: Example of the radiographic image classified as the over-filled canal.
Annex 6: Example of the radiographic image classified as the under-filled canal.
Annex 7: Example of the radiographic image classified as with the adequate root canal filling density.
Annex 8: Example of the radiographic image classified as with the inadequate root canal filling density.
Annex 9: Example of the radiographic image of the ledge.
Annex 10: Example of the radiographic image of the strip perforation [46].
Annex 11: Example of the radiographic image with the furcation perforation [47].
Annex 12: Example of the radiographic image of the separated instrument.
Annex 13: Example of the radiographic image with the adequate coronal sealing.
Annex 14: Example of the radiographic image with the inadequate coronal sealing.
EVALUATION FORM OF THE MASTER’S THESIS FOR THE MEMBER OF DEFENCE COMMITTEE
Graduate student ___________________________________________________________________, of the year ______, and the group _____ of the integrated study programme of Odontology
Master’s Thesis title: ………...……….………...………… ………...….………...……...
No. MT evaluation aspects
Evaluation Yes Partially No 1 Has the student’s presentation lasted for more than 10 minutes?
2 Has the student presented the main problem of the Master’s thesis, its aim and tasks?
3 Has the student provided information on research methodology and main research instruments?
4 Has the student presented the received results comprehensively?
5 Have the visual aids been informative and easy to understand?
6 Has the logical sequence of report been observed?
7 Have the conclusions been presented? Are they resulting from the results?
8 Have the practical recommendations been presented?
9 Have the questions of the reviewer and commission’s members been answered correctly and thoroughly?
10 Is the Master’s thesis in compliance with the essence of the selected study programme?
Remarks of the member of evaluation committee of Master’s Thesis
______________________________________________________________________________
______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________
Evaluation of the Master’s Thesis
_____________________________________________________________________________
Member of the MT evaluation committee:
________________ ___________________________ _____________________
(scientific degree) (name and surname) (signature)
Member of the MT evaluation committee:
________________ ___________________________ _____________________
(scientific degree) (name and surname) (signature)
