ATTITUDES AND PERSPECTIVES IN ENDODONTIC THERAPY WITH REGARD TO THE PROSTHETIC-RESTORATIVE APPROACH

Introduction Current context in interdisciplinary dentistry Collaboration between dental specialties, particularly endodontics and prosthodontics, requires active communication and a shared theoretical and practical foundation, enabling clinicians to adopt coherent, patient-centered solutions. Interdisciplinarity should not involve fragmented planning where each specialist focuses solely on a narrow part of the treatment plan. Endodontic therapy is intrinsically linked to the prosthetic-restorative strategy; it conditions prosthetic success, just as the restorative approach influences the long-term outcome of endodontically treated teeth. The prognosis depends on the quality of both the root canal procedure and the final restoration. Coronal microleakage and recontamination of the endodontic space may result from an improperly fitted crown, delayed completion of the final restoration or incorrect use of temporary restorations. Factors influencing clinical decision-making and research motivation Clinical decision-making processes exhibit significant variability and dentists often study only superficially the limitations of dental practice methods, instruments and equipment. This can lead to confidence that exceeds the actual sensitivity and specificity of these tools. Critical analysis of scientific data is essential in today's dental practice. Dentists need to continuously develop critical appraisal skills to select, interpret and apply relevant data; otherwise, therapeutic approaches based on incomplete or inaccurate information risk negatively impacting healthcare quality. This reality highlights the importance of this research, which aims to assess dentists’ cognitive and practical mechanisms in interdisciplinary decision-making to optimize clinical care quality. The three research directions chosen addressed diagnostic methods, microbiology and minimally invasive practice in endodontics. The final study integrated interdisciplinarity and decision-making algorithms. I. Current State of Knowledge 1. Contemporary Perspectives in Endodontics and the Role of Diagnostic Imaging Diagnostic terminology developed by the American Association of Endodontists (AAE) was globally recommended to promote consistency in clinical interpretation and treatment planning [1, 2]. However, significant variations remain among specialists and general dentists, especially in complex or inconclusive cases. Terms such as “Non-responsive regenerated pulp”, “Responsive regenerated pulp” and “Inconclusive pulp condition” have been proposed to enhance communication and accuracy [3]. Advanced imaging methods such as Cone-Beam Computed Tomography (CBCT), Magnetic Resonance Imaging (MRI) and ultrasonography provide more detailed investigation of dento-maxillary anatomy and overcome some limitations of conventional methods [4-10]. Accurate differentiation of periapical lesions remains difficult in standard dental practice [11-15]. Diagnosing periapical granuloma or apical radicular cyst from imaging is unreliable and may generate confusion in clinical practice and interdisciplinary communication. Cystic lesions account for approximately 15-20% of periapical lesions [6, 11, 16, 17]. Granulomas and pocket cysts are considered more likely to heal after orthograde treatment than true cysts, for which surgery may be required [6, 16]. Serial sectioned histological examination remains the only definitive method to confirm a continuous epithelial membrane in an apical cyst [6, 7, 11, 15, 16]. Although CBCT improves exploratory capacity, histology remains the method of choice for confirming a differential diagnosis [4, 8, 13]. Rational use of CBCT is recommended in complex cases where conventional imaging is insufficient, avoiding overuse due to increased ionizing radiation exposure [4]. Advanced imaging findings should be interpreted critically and cautiously. Understanding the limitations of paraclinical investigations, thorough theoretical knowledge and a detailed clinical examination are fundamental for effective diagnostic and therapeutic strategies. 2. Microbial Aetiology in Endodontic Disease Dental caries represent a primary route for microorganisms to access the endodontic system [18]. Bacteria, identified as the main etiological factor, advance into the root canal and influence pulp inflammation and periapical pathologies [17, 19, 20]. Contamination may also occur through cracks, leakage or periodontal disease. Bacterial virulence factors, including lipopolysaccharides from Gram-negative species, induce inflammation and stimulate pro-inflammatory mediators such as cytokines, contributing to periodontal ligament inflammation and bone resorption [17, 20-22]. Endodontic infections are often polymicrobial, with predominantly anaerobic communities including Enterococcus faecalis, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Actinomyces spp. [20, 21, 23]. The persistence of infection is mainly related to the ability of bacterial species to form biofilms [23, 24]. These three-dimensional communities adhere to dentinal surfaces and are embedded in an extracellular matrix, increasing resistance to antimicrobial agents [24, 25]. Enterococcus faecalis is frequently implicated in persistent infections, while extraradicular biofilms involving Actinomyces and Propionibacterium propionicum are associated with persistent periapical lesions [20, 23, 26, 27]. Management focuses on chemo-mechanical treatment, combining instrumentation with sodium hypochlorite (NaOCl) and EDTA [17, 24]. Sodium hypochlorite has antimicrobial and biofilm disruption activity, enhanced by ultrasonic irrigation, while chlorhexidine has limitations when used alone [21, 23, 25]. Despite advancements, complete biofilm removal remains a challenge and a central factor influencing treatment prognosis. 3. Mechanical Complications and Management of Separated Instruments in Endodontic Treatment Instrument fracture is a common procedural complication, with a reported prevalence of 0.4-23% [28]. Its incidence is influenced by instrument type, root canal anatomy and the clinician's experience and technique [28-31]. Curved or narrow canals, especially in the apical third, increase the risk [28, 30-32]. A fragment may obstruct access to the full canal length and prevent adequate chemo-mechanical treatment, increasing the probability of failure [33-35]. Management depends on fragment location and canal anatomy. Conventional mechanical techniques, including grasping devices, frequently require a staging platform and circumferential groove, causing excessive removal of hard tooth structure and increasing perforation risk [30, 32, 33, 36, 37]. Removal success is higher for fragments in the coronal and middle thirds (91.2%) than the apical third (79%), and before canal curvature (92%) rather than after it (50%) [33, 34, 38]. Longer fragments are generally more difficult and time-consuming to remove [29, 39]. The operating microscope is crucial for visibility and improved success [35]. 4. Integrating Prosthetic Considerations into the Endodontic Decision-making Process An interdisciplinary approach evaluates remaining tooth structure, restorability, the optimal restorative method and the patient’s occlusal, periodontal and systemic context [40-43]. Preserving hard tooth structure during endodontic therapy and the restorative plan supports long-term tooth retention [44]. Neglecting restorative considerations may reduce fracture resistance, compromise prognosis and promote coronal microleakage and recontamination [45-47]. Indirect restorations such as full crowns, endocrowns, onlays and overlays may provide superior mechanical strength for teeth with extensive coronal destruction [48-50], while post indications remain debated [42, 51, 52]. Integration of prosthetic considerations varies according to education, experience and access to technology [41, 52, 54]. Clearly defined clinical guidelines and a unified interdisciplinary decision-making algorithm remain absent [45, 55, 56]. II. Personal Contributions 5. Main Hypothesis and General Objectives Main hypothesis: "Assessment volatility, lack of interdisciplinary guidelines and dissentient integration of restorative-prosthetic principles into endodontic decision-making influence treatment outcome and foster disruptions". The foundation of this thesis arose from my clinical experience and professional interactions with referral dentists. The research studied inconsistencies in daily practice regarding endodontic diagnosis, perception and decision-making, focusing on interdisciplinarity and restorative considerations. Analysis of the endodontic-restorative interface can highlight clinical and scientific vulnerabilities and contribute to improving outcomes and tooth retention. General objectives: The main objective was to identify and analyze the reasons behind variability in assessment and clinical decision-making at the endodontic-restorative interface. Along with this main objective, the research included four milestone objectives: • Conduct high-level evidence-based research on the limitations of current imaging tools in periapical diagnosis. • Perform a comprehensive literature update on bacteria as the main etiological factor in endodontic disease. • Develop and clinically validate a minimally invasive technique that conserves healthy dentine during endodontic complication management. • Assess clinicians’ perception and decision-making patterns, validating personal clinical observations and identifying disruptions. 6. General Research Methodology This PhD thesis followed a three-path research protocol integrating two systematic reviews, a clinical case-report study presenting an innovative technique and a cross-sectional survey, addressing clinical inconsistencies under the interdisciplinary umbrella of endodontics and restorative dentistry. The systematic reviews examined the limitations of dental imaging and bacteria as the primary etiological factor in endodontic pathology. A new technique for separated instrument removal was developed to minimize tooth structure loss, regain access to the root canal anatomy and allow disinfection. Finally, the survey provided quantitative and qualitative data on practitioners’ perceptions and decision-making; advanced statistical analyses investigated dependencies, patterns and associations. Results from the four studies were critically discussed, leading to scientifically and clinically significant conclusions. 7. Study 1: “The Limitations of Periapical X-ray Assessment in Endodontic Diagnosis—A Systematic Review” Secondary hypothesis: "Limitations of periapical radiography and imaging differential diagnosis generate erroneous and divergent interpretations among dentists, directly affecting treatment planning". 7.1. Introduction Periapical X-ray is a two-dimensional image projecting three-dimensional anatomy, with potential detail superimposition. Attempting to differentiate cysts, granulomas or epithelial cells on periapical X-ray may therefore be an assumption. Although epithelial lining and clear margins are often associated with cyst diagnosis, 52% of periapical lesions contain organized epithelial cells while cystic lesions account for approximately 15% [15]. This is consistent with the reported 85% success rate of orthograde retreatment, although some cystic lesions may require a retrograde approach [57]. Lamina dura, lesion dimensions and density measurements do not correlate predictably with histological diagnosis, even when CBCT is used [10, 15, 58, 59]. The aim of this review was to compare histological diagnosis of apical cysts with periapical X-ray characteristics in high-quality studies. 7.2. Materials and Methods This systematic review was registered in PROSPERO (CRD42023406854) and followed PRISMA guidelines using the PICO framework. The clinical question examined the extent to which periapical imaging can diagnose periapical pathology and influence the clinical approach. Patients had apical periodontitis; periapical X-ray diagnosis was compared with histological examination to assess correlation and avoid misdiagnosis and overtreatment. Ovid Medline, PubMed, ScienceDirect, Mendeley and Scopus were searched using combinations of “periapical periodontitis”, “X-ray” or “Radiography”, “diagnosis” and “histology”. 7.2.1. Inclusion Criteria • Articles published in English or using English as a second language. • Articles using histopathology as the gold standard for periapical diagnosis. • Articles using periapical X-ray as the main or comparative imaging technique. 7.2.2. Exclusion Criteria • Book chapters, opinions, letters, narratives, commentaries and conference abstracts. • Studies not published in English. • Studies using other imaging techniques without clear differentiation. • Studies with induced pathology. 7.2.3. Study Selection Titles and abstracts were screened independently by two calibrated reviewers, with disagreements resolved by a third author. Full-text analysis followed the eligibility criteria. 7.2.4. Data Collection Process Two independent reviewers collected data during full-text analysis. Duplicates and ineligible studies were removed, and risk of bias and quality were assessed. 7.3. Results Following database and extended searches, 65 studies were reviewed and 16 met the inclusion criteria. Forty-nine publications were excluded for reasons including the use of other imaging techniques, lack of applicable information, cadaver studies, induced pathology and failure to differentiate imaging types. Quality scores ranged from 11 to 20.5 using an adapted McGrath et al. table. In a 22-year retrospective study, 68.4% of cases were diagnosed as cysts on X-ray, but only 15.6% were histologically confirmed [59]. In another study, radiographic assessment of inflammation corresponded to the histological category in 63% of cases [60]. Correlation between periapical X-ray and histology was weak (kappa = 0.104), and CBCT overestimated radicular cyst diagnosis by 8% compared with two-dimensional imaging [10]. Further studies reported marked discrepancies: radiological assessment classified 55% of lesions as cysts, whereas histology identified only 18.3% [61]; agreement between digital radiography and histopathology was approximately 60% [58]. Radiometric analysis suggested possible differentiation only without superimposition [62], but a larger study found no meaningful difference in measurements between granulomas and cysts [63]. A retrospective investigation reported 72% granulomas and 21.5% radicular cysts among persistent radiolucencies [11]. In a series of 57 lesions, 10 were histologically confirmed cysts; only 3 of 10 radiographic images with radiopaque lamina were cysts, while 7 of 47 lesions without a cyst-like image were histologically confirmed cysts. The authors recommended using the term “periapical radiolucent lesion” rather than cyst or granuloma based on imaging alone [11]. Earlier research found successful correlation in only 12.7% of cysts and 58.7% of granulomas [65]. Ultrasound showed promising accuracy of 86.7-100%, although studies had small samples [66]. 7.4. Discussion Available clinical diagnostic tools do not accurately translate histopathological status. Although the exact histological diagnosis may not always alter initial orthograde treatment, pocket cysts may heal after orthograde treatment whereas true cysts may require surgical intervention [11]. Periapical imaging lacks predictable features for cysts and granulomas, and the need for surgery cannot be determined by X-ray alone. Persistent apical pathology may reflect refractory intracanal infection, host response, foreign body reaction, extraradicular infection or cystic lesions [40, 71]. Even CBCT has discrepancies; no current clinical imaging tool is as accurate as histopathology for differentiating cysts from granulomas. Reported cyst incidence ranges from 6% to 55% but decreases to approximately 15% when serial section histology is used [15]. Ultrasound is promising, but limited samples and access restrict external validity [9, 72, 73]. Because available studies were performed under controlled conditions, improved diagnostic performance in private practice with radiographs of variable quality is unlikely. 7.5. Conclusions This review supports comprehensive assessment to avoid overtreatment and promote conservative approaches. Radiological diagnosis remains inaccurate and should be interpreted cautiously. Dentists should explain treatment options and consider specialist referral when limited by training, skills, experience or confidence. Further well-designed research and greater awareness of periapical X-ray limitations are required. 8. Study 2: “Dental pathologies of endodontic origin and subsequent bacterial involvement – a literature review” Secondary hypothesis: "Bacterial biofilm is the main etiological factor in endodontic pathologies and its effective control through a rigorous disinfection protocol is decisive for treatment success". 8.1. Introduction Dental pathologies of endodontic origin commonly begin with caries or trauma, allowing microbial invasion of the pulp. Inflammation may progress from reversible to irreversible pulpitis and pulp necrosis; bacteria then form predominantly anaerobic communities within the root canal system [76]. 8.2. Review Polymicrobial infections are common. Bacterial virulence factors and byproducts trigger inflammation and tissue destruction in the periapical region, contributing to granulomas, cysts and abscesses [77-79]. Enterococcus, Porphyromonas, Prevotella, Fusobacterium and Actinomyces are frequently involved [80-83], while Enterococcus faecalis is associated with persistent post-treatment infection [84, 85]. Biofilm organization protects bacteria from host defences and antimicrobial agents and contributes to persistence, especially in areas inaccessible to instruments [86-88]. Extraradicular biofilms are also associated with persistent periapical lesions [89]. 8.2.1. Updates in the Management of Endodontic Infections Chemo-mechanical treatment combines instrumentation with irrigants to remove infected tissue, bacteria and biofilms [90]. Sodium hypochlorite is the gold standard for tissue dissolution and biofilm disruption and is often alternated with EDTA [24]. Passive ultrasonic irrigation, laser-based methods and intracanal calcium hydroxide may enhance antimicrobial action, while chlorhexidine has limitations against mature biofilms [24, 91, 92]. Complete biofilm elimination nevertheless remains a major challenge influencing prognosis and therapeutic strategy. 8.3. Conclusions Bacteria play an important role in endodontic pathogenesis. Management should address bacterial biofilms alongside planktonic bacteria and consider novel local treatment methods. 9. Study 3: “The Platformless Technique (PFLT): A Minimally Invasive Technique for Removing Separated Instruments: Case Report Study” Secondary hypothesis: "Preservation of dental hard tissues by minimally invasive techniques such as Platformless Technique (PFLT) allows predictable extraction of separated instruments, regaining root canal patency and optimizing interdisciplinary therapeutic success". 9.1. Introduction Removing fractured instruments is challenging and depends on fragment location and canal morphology [93]. Traditional grasping techniques often require a staging platform and circumferential groove, increasing the risk of excessive dentine removal and iatrogenic damage [28, 32, 38, 95]. The therapeutic approach should preserve healthy dentine to avoid weakening the tooth. The Platformless Technique (PFLT) was developed to eliminate the platform stage and was described in three cases with two- to five-year imaging follow-up. 9.2. Materials and Methods PFLT uses a microscope and creates a bypass with a stainless-steel ultrasonic file after a final shaping file reveals the separated fragment, avoiding cutting burs or Gates Glidden drills. Depending on fragment position, a pre-bent ISO 15 ultrasonic K-file is used at low intensity within the available canal space. Continuous irrigation with 3-5% sodium hypochlorite is mandatory for debris evacuation, cooling and disinfection, and 17% EDTA is recommended during removal. Controlled force, patience and tactile feedback are required. Conservative pre-flaring with a final shaper, for example a 25/0.6 mechanical file, may enlarge the space without creating a platform. Pre-operative CBCT and an apex locator attached to the U-file can guide bypass and reduce iatrogenic risk. 9.3. Case Presentations 9.3.1. Case 1 A 52-year-old female with symptomatic apical periodontitis presented a fractured instrument in the middle/apical third of a mesial canal, a large apical lesion involving both root apices and a screwed metal post in the distal canal beneath a crown. After crown and post removal, a 25/0.6 instrument revealed the fragment, which was bypassed with an ISO 15 U-file under sodium hypochlorite irrigation. The fragment was removed, patency re-established and the canal obturated. 9.3.2. Case 2 A 20-year-old male with pain on biting presented multiple fractured instruments in a mandibular first molar. CBCT guided minimally invasive management. The fragments were removed using PFLT, followed by shaping, cleaning and sealing. Five-year follow-up showed complete remission of the lesion. 9.3.3. Case 3 A 43-year-old female was referred after a previous platform approach had already sacrificed excessive pericervical dentine. No additional pre-flaring was performed, and the instrument was removed directly using U-files. A fibre post was placed in the distal canal and post-endodontic restoration was completed. Two-year follow-up showed complete periapical healing without reported complications. 9.4. Results In all three cases, symptoms resolved after treatment and chewing function was restored. Follow-up demonstrated long-term stability with a conservative and minimally invasive approach. 9.5. Discussion Fragment length, instrument type, location, accessibility, canal morphology, equipment and operator skills influence difficulty and success. PFLT is an orthograde technique that preserves original anatomy and avoids removal of healthy tissue around the coronal fragment. Unlike a 360° platform created with trephine burs, conservative pre-flaring and a pre-bendable ISO 15 ultrasonic K-file reduce dentine loss and iatrogenic risk. The operating microscope is essential. 9.6. Conclusions PFLT offers clinicians a conservative approach that supports predictability, minimal invasiveness and patient-centered care. 10. Study 4: “A Cross-Sectional Survey Assessing the Factors Influencing Dentists’ Decisions on Post-Endodontic Prosthetic Crown Restoration” Secondary hypothesis: "The lack of a unified decision-making algorithm affects the coherent integration of prosthetic considerations into endodontic therapy, reducing predictability and interdisciplinary success". 10.1. Introduction Endodontic therapy aims to preserve teeth with pulpal and periapical diseases [96]. Successful outcomes depend on root canal quality, yet clinical approaches and decision-making vary [97]. This study assessed Romanian dentists’ diagnostic imaging preferences, restorative decisions and integration of prosthetic planning. Identifying disparities in post-endodontic crown placement could inform national policy reforms, guidelines, education, standardized timing protocols and interdisciplinary referral criteria. 10.2. Materials and Methods A cross-sectional electronic survey, part of a larger multicentric study, was conducted among Romanian dentists after ethical approval from the Carol Davila University Ethics Committee. Participation was voluntary and anonymous, with electronic informed consent. The questionnaire included demographic data, diagnostic imaging preferences and restorative decision factors. Content validity was reviewed by endodontists and prosthodontists (CVI > 0.7). Pilot testing assessed clarity and relevance, while a second pilot assessed internal consistency (Cronbach’s alpha > 0.7). Dentists were recruited through professional networks and associations and required a valid licence, active practice in Romania and Romanian fluency. Of 238 complete responses, 20 students were excluded, leaving 218 for analysis, with a ±6.6% margin of error at 95% confidence. No missing-data handling was required. Descriptive statistics, Chi-square tests and logistic regression were used. 10.3. Results Periapical radiography was used most frequently (83.49%), followed by CBCT (53.67%) and panoramic radiography (48.17%). More than 70% reported high confidence in CBCT accuracy for differentiating cysts and granulomas, significantly exceeding perceived periapical X-ray accuracy. Nevertheless, this confidence did not significantly increase immediate invasive choices such as apicoectomy or extraction. Retreatment, monitoring and specialist referral were generally preferred. Endodontists were approximately five times less likely than other specialists to choose an invasive approach. A hypothetical minimally invasive histological diagnostic tool shifted 81.65% of respondents towards conservative decisions. A majority (69.3%) would postpone definitive restoration until complete radiographic healing of an ongoing periapical lesion. Endodontists showed no statistically significant preference for postponement, while other specialties strongly preferred delay. Endodontists prioritised feasibility of successful restorative outcomes and assigned greater importance to root canal complexity, radiographic lesion characteristics and fractured instruments when deciding between preservation and extraction. Non-endodontic specialists gave relatively greater importance to financial considerations and patient preference. Tooth fracture risk was highly important across all groups. 10.4. Discussion The findings demonstrate a discrepancy between perceived CBCT diagnostic capability and scientific evidence, creating a risk of misdiagnosis and inappropriate therapy [10-12, 15, 60]. Decisions appear influenced by specialty training, clinical experience, patient context, treatment philosophy, cognitive biases and potentially defensive dentistry. Delaying definitive restoration despite the risks of coronal leakage and tooth fracture may reflect a cautious or defensive approach [98, 99]. 10.5. Conclusions Comprehensive evidence-based guidelines and ongoing interdisciplinary education are required. Recommendations include national and international guidance on crown placement timing, for example within four weeks for premolars, targeted training in radiographic interpretation and standardized electronic health record templates for integrated endo-prosthodontic planning. Structured protocols should reduce decision-making discrepancies, improve predictability and enhance tooth survival. 11. Conclusions and Personal Input Clinical assessment algorithms are often based on intuition and experience, leading to subjectivity and inconsistency. The volume and rapid updating of publications are substantial [100], while evidence levels below 20% reported in some studies remain concerning [101-103]. Clinicians may find it difficult to accept that vision and radiological imaging can be inaccurate compared with direct examination or histology [104-106]. Confirmation bias encourages selective searching for consistent information [107], although low evidence is not no evidence and personal experience retains value [108, 109]. The brain uses verbatim and gist representations; reliance on gist develops with experience but remains vulnerable to bias and fuzzy memories [98, 110]. The studies identified important discrepancies. Despite evidence that periapical X-rays and CBCT cannot reliably differentiate periapical lesions, many dentists reported high confidence in CBCT. Specialties prioritised diagnostic and restorative factors differently, while endodontists placed particular emphasis on restorability. Contrary to evidence supporting timely coronal sealing, most dentists would postpone definitive crown restoration during apical healing. These patterns support the main hypothesis by demonstrating that clinical decisions are influenced not only by evidence but also by training, experience and treatment philosophy. Interdisciplinary approaches and collective intelligence are crucial for complex cases [98, 111-115], despite communication barriers, conflicting opinions, costs and concerns regarding access to specialized care [112, 113]. This volatile context may promote defensive dentistry and delayed treatment [99]. The endodontic-restorative interface therefore requires clear, evidence-based interdisciplinary guidelines to reduce incoherent decision-making, improve treatment predictability and support long-term tooth retention.