A Novel Educational Approach for Safe Endodontic Syringe Irrigation: A Randomized Controlled In Vitro Study.

OBJECTIVE: Syringe irrigation, commonly used for delivering sodium hypochlorite (NaOCl) during root canal treatment, requires careful handling to prevent NaOCl extrusion into periapical tissues. This randomized controlled in vitro study aimed to quantify syringe plunger forces exerted by dental undergraduates and to assess the impact of an educational intervention on adherence to safe irrigant delivery parameters. METHODS: Fifty-two undergraduates performed syringe irrigation at three intervals: baseline (T1), after two weeks (T2), and after 12 weeks (T3). At T1, irrigation was conducted without prior educational intervention, while at T2, it was preceded by an intervention. The educational intervention involved a short video highlighting safe irrigation practices, including plunger force and time recommendations for syringe irrigation. At T3, the undergraduates were randomly allocated to two groups: One received a repeated intervention, while the other did not. Syringe irrigation was performed on a 3D-printed tooth using two side-vented cannulas: one of 25 Gauge (G) and another of 30 G. A syringe equipped with a force sensor recorded the plunger forces. Based on earlier research, plunger forces exceeding 10 Newtons (N) for the 25 G cannula and 40 N for the 30 G cannula were deemed critical. The data were subjected to descriptive statistical analyses. RESULTS: Overall, the mean of maximum values of plunger forces remained under 10 N for the 25 G and below 20 N for the 30 G cannulas, with only few measurements exceeding 40 N. Instances of surpassing the critical plunger force threshold were more common with the 25 G side-vented cannula than with the 30 G variant. At T3, the group that received the repeated educational intervention exhibited lower average maximum plunger forces for both types of cannulas compared with the group that did not receive the intervention. CONCLUSION: Integrating plunger force measurements with targeted educational interventions presents an effective approach for instructing undergraduates in the proper techniques of syringe irrigation. The findings suggest that, generally, undergraduates do not apply excessive plunger forces that could risk apical irrigant extrusion. The implementation of repeated educational interventions has been shown to decrease the plunger forces exerted by undergraduates, underscoring its effectiveness in fostering safe endodontic irrigation.

Impact of treatment of rheumatoid arthritis on periodontal disease: A review.

BACKGROUND: Numerous studies support a bidirectional association between rheumatoid arthritis (RA), a chronic autoimmune degenerative inflammatory joint disease, and periodontitis, a chronic inflammatory disease caused by the immune reaction to bacteria organized in biofilms. RA and periodontitis are both multifactorial chronic inflammatory diseases that share common modifiable and non-modifiable risk factors. There is no cure for RA; treatment is based on lifestyle modifications and a variety of medications: nonsteroidal anti-inflammatory drugs (NSAID), glucocorticoids, and disease-modifying antirheumatic drugs (DMARDs, e.g., conventional synthetic DMARDs [csDMARDs]; biological DMARDs [bDMARD] and targeted synthetic DMARDs). There are molecular pathways of inflammation that are common to both RA and periodontitis. Thus, there is a potential effect of RA treatments on periodontitis. This systematic review aims to assess the impact of antirheumatic agents on periodontal conditions of patients suffering from both RA and periodontitis. METHODS: PubMed/MEDLINE, Cochrane Library, and Embase online databases were systematically explored, and a manual search was performed to identify relevant studies published until January 2023. This review is registered in the PROSPERO database (CRD42023409006). RESULTS: A total of 2827 articles were identified, and 35 fulfilled the inclusion criteria. The included studies generally show a consensus that, at normal dosage, NSAID and corticosteroids have negligible impact on periodontium. Similarly, csDMARD alone or in combination with other csDMARD demonstrated no adverse effect on periodontium. Monotherapy with bDMARD had a positive effect on periodontal pocket depths and gingival inflammation in the longitudinal studies up to 6 months but showed negligible effect on the periodontium in interventional studies with a longer follow-up (9 months and 15.1 months). However, the combination of tumor necrosis factor (TNF)-α inhibitors + methotrexate (MTX) was associated with a rise in gingival inflammation. Due to the considerable heterogeneity of the study designs, a meta-analysis could not reasonably be performed. CONCLUSION: Within the limitations of the available studies, there is evidence to suggest that bDMARD monotherapy may improve the periodontal condition of RA patients with periodontal disease to a certain extent; the concomitant medication of TNF inhibitor + MTX could worsen gingival inflammation. More data are required to understand the impact of RA therapies on periodontal health.

Impact of oral piercings on periodontal health - A systematic review.

AIM: Evidence on the impact of oral piercings on periodontal conditions is scarce. Thus, the aim of this systematic review was to evaluate the influence of oral piercings on periodontal health. MATERIALS AND METHODS: A systematic literature search was performed for studies published by 6 June 2023, using three electronic databases and a hand search. Clinical trials including ≥10 patients wearing ≥1 oral piercing and presenting data on probing pocket depths (PPDs) were considered. Primary outcomes were PPD, and secondary outcomes included clinical attachment loss (CAL), gingival recession, bleeding on probing (BOP), and plaque score (PI). A synthesis of results, using a vote-counting method, was applied. RESULTS: From 131 titles identified, eight studies, published between 2007 and 2022, were included. Out of these were six cross-sectional studies and two case series. A total of 236 lip piercings and 236 tongue piercings in overall 408 patients were analyzed. In patients with tongue piercings, teeth adjacent to the piercing showed increased PPD (3 of 5 studies), more CAL (3 of 4 studies), more gingival recessions (4 of 4 studies) and a higher BOP (2 of 3 studies) compared with control teeth. In patients with lip piercings, teeth adjacent to the piercing demonstrated more gingival recessions (3 of 4 studies) compared with control teeth. Time since piercing placement was associated with localized periodontal destruction in patients with tongue and/or lip piercings (4 of 7 studies). CONCLUSIONS: The available evidence from eight studies suggests negative effects of tongue piercings on several periodontal health parameters of adjacent teeth, while gingival recessions were frequently detected in patients with lip piercings.

ChatGPT's performance in dentistry and allergy-immunology assessments: a comparative study.

Large language models (LLMs) such as ChatGPT have potential applications in healthcare, including dentistry. Priming, the practice of providing LLMs with initial, relevant information, is an approach to improve their output quality. This study aimed to evaluate the performance of ChatGPT 3 and ChatGPT 4 on self-assessment questions for dentistry, through the Swiss Federal Licensing Examination in Dental Medicine (SFLEDM), and allergy and clinical immunology, through the European Examination in Allergy and Clinical Immunology (EEAACI). The second objective was to assess the impact of priming on ChatGPT's performance. The SFLEDM and EEAACI multiple-choice questions from the University of Bern's Institute for Medical Education platform were administered to both ChatGPT versions, with and without priming. Performance was analyzed based on correct responses. The statistical analysis included Wilcoxon rank sum tests (α=0.05). The average accuracy rates in the SFLEDM and EEAACI assessments were 63.3% and 79.3%, respectively. Both ChatGPT versions performed better on EEAACI than SFLEDM, with ChatGPT 4 outperforming ChatGPT 3 across all tests. ChatGPT 3's performance exhibited a significant improvement with priming for both EEAACI (p=0.017) and SFLEDM (p=0.024) assessments. For ChatGPT 4, the priming effect was significant only in the SFLEDM assessment (p=0.038). The performance disparity between SFLEDM and EEAACI assessments underscores ChatGPT's varying proficiency across different medical domains, likely tied to the nature and amount of training data available in each field. Priming can be a tool for enhancing output, especially in earlier LLMs. Advancements from ChatGPT 3 to 4 highlight the rapid developments in LLM technology. Yet, their use in critical fields such as healthcare must remain cautious owing to LLMs' inherent limitations and risks.

Guided endodontics versus conventional access cavity preparation: an ex vivo comparative study of substance loss.

BACKGROUND: To compare the outcomes of conventional access cavity preparation (CONV) versus guided endodontics (GE) for access cavity preparation in anterior teeth with pulp canal calcification (PCC) regarding root canal detection, substance loss, procedural time, and need for additional radiographs. METHODS: Extracted, sound human teeth with PCC (n = 108) were matched in pairs, divided into two groups and used to produce 18 models. An independent endodontist and a general dentist performed access cavity preparation under simulated clinical conditions on nine models each (54 teeth). The endodontist used the conventional technique and the general dentist GE. Time needed to access the root canals and the number of additional radiographs were recorded. Pre- and postoperative cone-beam computed tomography scans were obtained to measure substance loss. Statistical significance was tested by examining the overlap of 95% confidence intervals (CIs) between the groups. RESULTS: All root canals were successfully accessed by both methods. There were no significant differences in substance loss (CI: CONV 15.9-29.6 mm3 vs. GE 17.6-27.5mm3) or procedural time (CI: CONV 163.3-248.5 s vs. GE 231.9-326.8 s). However, 31 additional radiographs were required for GE compared to none for CONV. CONCLUSIONS: For access cavity preparation in teeth with PCC, both CONV by a specialist and GE by a general dentist produce good results in terms of substance loss and time requirements.

Exploring the staining potential of 1 GSK-3 inhibitors in bovine teeth: 2 a one-year laboratory investigation.

GSK-3 inhibitors, such as Tideglusib (TG) and CHIR-99021 (CHIR), show promise in stimulating reparative dentin formation. The aim of this study was to assess the discoloration potential of TG and CHIR in an established in vitro model. Enamel-dentin specimens made from bovine incisors were randomly allocated to five groups (n=15 each): group bovine blood (BB), group dimethyl sulfoxide (DMSO), group TG, group CHIR, and group mineral trioxide aggregate (MTA). Each specimen had a central cavity in which the respective material was applied and sealed with resin-based luting material. Color determination was conducted using a dental spectrophotometer at t0 (before filling), t1 (immediately after filling), t2 (after one week), t3 (after one month), t4 (after three months), t5 (after six months), and t6 (after one year). Statistical analysis involved descriptive statistics, Kruskal-Wallis tests, and analysis of variance (α=0.05). Group BB and group CHIR exhibited the most significant decrease in lightness (ΔL*) after one year (ΔL*-4.7 and ΔL* -5.7, respectively), whereas groups DMSO, TG, and MTA showed minimal changes (DMSO ΔL*: -0.3; TG ΔL*: 1.4; MTA ΔL*: -0.5). Group BB and CHIR exhibited the highest ΔE values (6.4Å}0.6 and 6.5Å}0.8, respectively). Unlike CHIR, TG did not result in discoloration exceeding the threshold of visual perception, defined by a ΔE value of 5.5, during the one-year observation period. This laboratory study therefore suggests that TG could be utilized for indirect or direct pulp capping without major discoloration concerns. However, additional research is required to corroborate these findings.

Implications of large language models such as ChatGPT for dental medicine.

OBJECTIVE: This article provides an overview of the implications of ChatGPT and other large language models (LLMs) for dental medicine. OVERVIEW: ChatGPT, a LLM trained on massive amounts of textual data, is adept at fulfilling various language-related tasks. Despite its impressive capabilities, ChatGPT has serious limitations, such as occasionally giving incorrect answers, producing nonsensical content, and presenting misinformation as fact. Dental practitioners, assistants, and hygienists are not likely to be significantly impacted by LLMs. However, LLMs could affect the work of administrative personnel and the provision of dental telemedicine. LLMs offer potential for clinical decision support, text summarization, efficient writing, and multilingual communication. As more people seek health information from LLMs, it is crucial to safeguard against inaccurate, outdated, and biased responses to health-related queries. LLMs pose challenges for patient data confidentiality and cybersecurity that must be tackled. In dental education, LLMs present fewer challenges than in other academic fields. LLMs can enhance academic writing fluency, but acceptable usage boundaries in science need to be established. CONCLUSIONS: While LLMs such as ChatGPT may have various useful applications in dental medicine, they come with risks of malicious use and serious limitations, including the potential for misinformation. CLINICAL SIGNIFICANCE: Along with the potential benefits of using LLMs as an additional tool in dental medicine, it is crucial to carefully consider the limitations and potential risks inherent in such artificial intelligence technologies.

ESE position statement on root resorption.

This Position Statement on root resorption represents the consensus of an expert committee convened by the European Society of Endodontology (ESE). The statement is based on current clinical and scientific evidence as well as the expertise of the committee. The aim is to provide clinicians with authoritative information on the aetiology, histopathology, clinical presentation and recommendations for the management of root resorption. It is the intention of the committee to update this position statement at appropriate intervals as further evidence emerges.

Quality of CAD-CAM inlays placed on aged resin-based composite restorations used as deep margin elevation: a laboratory study.

OBJECTIVES: To assess the impact of the age of resin-based composite (RBC) restorations used for deep margin elevation (DME) on the marginal quality and fracture resistance of inlays. MATERIALS AND METHODS: Permanent human molars with direct RBC restorations, involving the mesial, occlusal, and distal surface (MOD), were allocated to four groups (each n = 12). Half of the teeth underwent thermomechanical loading including 240,000 occlusal load cycles and 534 thermal cycles (TML, 5 °C/55 °C; 49 N, 1.7 Hz). With RBC left in one proximal box as DME, all teeth received MOD inlays, made from lithium disilicate (LDS) or a polymer-infiltrated ceramic network material (PICN). The restored teeth underwent TML including 1.2 million occlusal cyclic loadings and 2673 thermal cycles. The marginal quality was assessed at baseline and after both runs of TML. Load-to-fracture tests were performed. The statistical analysis comprised multiple linear regressions (α = 0.05). RESULTS: Simulated aging of RBC restorations had no significant effect on the marginal quality at the interface between the RBC and the tooth and the RBC and the inlay (p ≥ 0.247). Across time points, higher percentages of non-continuous margin were observed between the inlay and the tooth than between the tooth and the RBC (p ≤ 0.039). The age of the DME did not significantly affect the fracture resistance (p ≥ 0.052). CONCLUSIONS: Artificial aging of RBC restorations used for DME had no detrimental effect on the marginal quality and fracture resistance of LDS and PICN inlays. CLINICAL RELEVANCE: This laboratory study suggests that-in select cases-intact, direct RBC restorations not placed immediately before the delivery of an indirect restoration may be used for DME.

ChatGPT's performance in dentistry and allergyimmunology assessments: a comparative study.

Large language models (LLMs) such as ChatGPT have potential applications in healthcare, including dentistry. Priming, the practice of providing LLMs with initial, relevant information, is an approach to improve their output quality. This study aimed to evaluate the performance of ChatGPT 3 and ChatGPT 4 on self-assessment questions for dentistry, through the Swiss Federal Licensing Examination in Dental Medicine (SFLEDM), and allergy and clinical immunology, through the European Examination in Allergy and Clinical Immunology (EEAACI). The second objective was to assess the impact of priming on ChatGPT's performance. The SFLEDM and EEAACI multiple-choice questions from the University of Bern's Institute for Medical Education platform were administered to both ChatGPT versions, with and without priming. Performance was analyzed based on correct responses. The statistical analysis included Wilcoxon rank sum tests (alpha=0.05). The average accuracy rates in the SFLEDM and EEAACI assessments were 63.3% and 79.3%, respectively. Both ChatGPT versions performed better on EEAACI than SFLEDM, with ChatGPT 4 outperforming ChatGPT 3 across all tests. ChatGPT 3's performance exhibited a significant improvement with priming for both EEAACI (p=0.017) and SFLEDM (p=0.024) assessments. For ChatGPT 4, the priming effect was significant only in the SFLEDM assessment (p=0.038). The performance disparity between SFLEDM and EEAACI assessments underscores ChatGPT's varying proficiency across different medical domains, likely tied to the nature and amount of training data available in each field. Priming can be a tool for enhancing output, especially in earlier LLMs. Advancements from ChatGPT 3 to 4 highlight the rapid developments in LLM technology. Yet, their use in critical fields such as healthcare must remain cautious owing to LLMs' inherent limitations and risks.

Detection and Removal of Tooth-Colored Composite Resin using the Fluorescence-Aided Identification Technique.

The detection and removal of tooth-colored filling materials is a major challenge for every dentist. The Fluorescence-aided Identification Technique (FIT) is a noninvasive tool to facilitate the distinction of composite resin material from sound tooth substance. Compared to conventional illumination, FIT is a very accurate, reliable, and fast diagnostic method. When composite resin is illuminated with a wavelength of approximately 398 ± 5 nm, certain fluorescent components make the composite resin appear brighter than the tooth structure. Any fluorescence-inducing light source with the appropriate wavelength can be used for this method. Optimally, this technique is used without additional natural or artificial lighting. The application of FIT can be used for diagnostic purposes, for example, dental charts, and additionally for the complete and minimally invasive removal of composite resin restorations, bracket debonding, and trauma splint removal. The assessment of volumetric changes after composite removal can be provided by overlapping pre- and postoperative scans and subsequent calculation using suitable software.

Guided Endodontics: Three-dimensional Planning and Template-aided Preparation of Endodontic Access Cavities.

Pulp canal obliterations (PCO) are often a consequence of dental trauma, such as luxation injuries. Even though dentin apposition is a sign of vital pulp, pulpitis or apical periodontitis may develop in the long term. Root canal treatment of teeth with severe PCO and pulpal or periapical pathosis is challenging for general practitioners and even for well-equipped endodontic specialists. To ensure detection of the calcified root canal and avoid excessive loss of tooth structure or root perforation, static navigation using templates ("Guided Endodontics") was introduced a few years ago. The general workflow includes three-dimensional imaging using cone-beam computed tomography (CBCT), a digital surface scan, and superimposition of both in a planning software. This is followed by virtual planning of the access cavity and the design of a template that will guide the drill to the desired target point. To do this, a true-to-scale virtual image of the drill must be placed in a way that the tip of the drill reaches the orifice of the calcified root canal. Once the template has been fabricated using computer-aided design and computer-aided manufacturing (CAD/CAM) or a 3D printer, guided preparation of the access cavity can be performed clinically. For research purposes, a postoperative CBCT image can be used to quantify the accuracy of the access cavity performed. This work aims to present the technique of static guided endodontics from imaging to clinical implementation.

Dynamic Navigation in Endodontics: Guided Access Cavity Preparation by Means of a Miniaturized Navigation System.

In the case of teeth with pulp canal calcification (PCC) and apical pathology or pulpitis, root canal treatment can be very challenging. PCC are common sequelae of dental trauma but can also occur with stimuli such as caries, bruxism, or after placing a restoration. In order to access the root canal as minimally invasive as possible in case of a necessary root canal treatment, dynamic navigation has recently been introduced in endodontics in addition to static navigation. The use of a dynamic navigation system (DNS) requires pre-operative cone-beam computed tomography (CBCT) imaging and a digital surface scan. If necessary, reference markers must be placed on the teeth before the CBCT scan; with some systems, these can also be planned and created digitally afterward. By means of a stereo camera connected to the planning software, the drill can now be coordinated with the help of reference markers and virtual planning. As a result, the position of the drill can be displayed on the monitor in real-time during preparation in different planes. In addition, the spatial displacement, the angular deviation, and the depth position are also displayed separately. The few commercially available DNS mostly consist of relatively large camera-marker-systems. Here, the DNS contains miniaturized components: a low-weight camera (97 g) mounted on the micromotor of the electric handpiece utilizing a manufacturer-specific connecting mechanism and a small marker (10 mm x 15 mm), which can be easily attached to an individually manufactured intraoral tray. For research purposes, a post-operative CBCT scan can be matched with the pre-operative one, and the volume of tooth structure removed can be calculated by the software. This work aims to present the technique of guided access cavity preparation by means of a miniaturized navigation system from imaging to clinical implementation.

Present status and future directions - Guided endodontics.

Luxation injuries and other stimuli may lead to a pulp canal obliteration (PCO). Even though the apposition of tertiary dentine is a sign of a vital pulp, in some cases root canal treatment is indicated in the long term due to apical periodontitis or pulpitis. Depending on the extent of PCO, root canal treatment may be challenging even for experienced and well-equipped endodontic specialists. The 'guided endodontics' (GE) technique was introduced 6 years ago as an alternative to conventional access cavity preparation for teeth with PCO and apical pathosis or irreversible pulpitis. Using three-dimensional radiological imaging such as cone-beam computed tomography and a digital surface scan, an optimal access to the orifice of the calcified root canal can be planned virtually with appropriate software. GE is implemented either with the help of templates analogous to guided implantology (= static navigation) or by means of dynamic navigation based on a camera-marker system. GE has emerged as a field of research in the last 6 years with very promising laboratory-based results regarding the accuracy of guided endodontic access cavities for both static and dynamic navigation. Clinical implementation seems to provide favourable results, but the evidence is mainly based on numerous case reports and a few case series. This narrative review aims to provide an update on the present status of GE and to identify relevant research areas that could contribute to further improvements of this technique.

Present status and future directions: Endodontic management of traumatic injuries to permanent teeth.

The prognosis of traumatized teeth depends largely on the fate of the pulp and its treatment. This review aims to update the present status on the endodontic management of traumatic injuries to permanent teeth and to identify relevant research areas that could contribute to an improvement in diagnosis and treatment of traumatized permanent teeth. Future research should pay greater attention to (1) diagnostic methods to assess the perfusion of the pulp and enhance detection of tooth cracks and initial signs of root resorption; (2) improved materials for vital pulp treatment; (3) studies focusing on type and duration of splinting after root fractures; (4) antiresorptive intracanal medication in case of posttraumatic pulp necrosis and infection-related resorption and (5) long-term data on the apical barrier technique compared to revitalization.

Partial pulpotomy without age restriction: a retrospective assessment of permanent teeth with carious pulp exposure.

OBJECTIVES: This study aimed to retrospectively evaluate clinical and radiographic outcomes of partial pulpotomy performed in permanent teeth with carious pulp exposure. MATERIALS AND METHODS: Records of patients undergoing treatment at an undergraduate dental clinic between 2010 and 2019 were screened for partial pulpotomies in teeth with a presumptive diagnosis of normal pulp or reversible pulpitis. The follow-up had to be ≥ 1 year. Patient data were retrieved and analyzed using Mantel-Cox chi square tests and Kaplan-Meier statistics. The level of significance was set at α = 0.05. RESULTS: Partial pulpotomy was performed in 111 cases, of which 64 (58%) fulfilled the eligibility criteria. At the time of partial pulpotomy, the mean age was 37.3 (± 13.5) years (age range 18-85). The mean observation period was 3.1 (± 2.0) years. Two early failures (3.1%) and five late failures (7.7%) were recorded. The overall success rate of maintaining pulp vitality was 89.1%, with 98.4% tooth survival. The cumulative pulp survival rates of partial pulpotomy in patients aged < 30 years, between 30 and 40 years, and > 40 years were 100%, 75.5%, and 90.5%, respectively, with no significant difference between the age groups (p = 0.225). At follow-up, narrowing of the pulp canal space and tooth discoloration were observed in 10.9% and 3.1% of cases, respectively. CONCLUSIONS: Across age groups, partial pulpotomy achieved favorable short and medium-term outcomes in teeth with carious pulp exposure. CLINICAL RELEVANCE: Adequate case selection provided, partial pulpotomy is a viable operative approach to treat permanent teeth with deep carious lesions irrespective of patients' age.

Effect of repeated ultrasonic instrumentation on single-unit crowns: a laboratory study.

OBJECTIVES: This laboratory study aimed to assess the effects of ultrasonic instrumentation, simulating 10 years of supportive periodontal therapy (SPT), on single-unit crowns. MATERIALS AND METHODS: Standardized crowns were fabricated from porcelain-fused-to-metal (PFM) (n = 12), zirconia (ZrO2) (n = 12), lithium disilicate (LDS) (n = 12), feldspar ceramic (FSFC) (n = 6), and polymer-infiltrated ceramic network material (PICN) (n = 6). The crowns, luted on PICN abutments with resin-based luting material (RBLM), and if applicable glass ionomer cement (GILC), underwent thermal cycling and trimonthly ultrasonic instrumentation. After 1 and 10 years of simulated SPT, restoration quality assessments were performed, comprising profilometric surface roughness measurements, marginal integrity evaluations, and scores for luting material remnants and visible cracks. The statistical analysis included multiple logistic regressions with nested designs (α = 0.05). RESULTS: During simulated SPT, bulk fractures (n = 2) and a de-cementation failure (n = 1) of LDS and ZrO2 crowns were observed. No significant change in roughness was detected after 10 years (p = 0.078). Over time, marginal defects increased (p = 0.010), with PFM crowns showing the highest rate of chippings at sites with a narrow shoulder. Fewer marginal defects were detectable on crowns luted with RBLM compared with GILC (p = 0.005). Luting material remnants decreased during SPT (p < 0.001). Ultrasonic instrumentation caused cracks in most crown materials, in particular at sites with a narrow shoulder and in PFM crowns. CONCLUSIONS: Repeated ultrasonic instrumentation may damage single-unit crowns. PFM crowns with a narrow, all-ceramic margin are especially prone to defects. CLINICAL RELEVANCE: Frequent ultrasonic instrumentation of restoration margins of fixed dental prostheses, PFM crowns in particular, ought to be avoided.

Real-Time Guided Endodontics with a Miniaturized Dynamic Navigation System Versus Conventional Freehand Endodontic Access Cavity Preparation: Substance Loss and Procedure Time.

INTRODUCTION: This study aimed to evaluate substance loss and the time required for access cavity preparation (ACP) using the conventional freehand method (CONV) versus a miniaturized dynamic navigation system of real-time guided endodontics (RTGE) in an in vitro model using 3-dimensional-printed teeth. METHODS: Nine human anterior maxillary teeth were selected and micro-computed tomographic scanned. Root canals were virtually reduced to 2 mm below the cementoenamel junction. The teeth were digitally duplicated and mirrored to yield 6 different models with 6 single-rooted teeth each. The models were 3-dimensionally printed using radiopaque resin and consecutively mounted on a dental mannequin for ACP. Two operators with 12 and 2 years of clinical experience, respectively, received 6 models (36 teeth) each and performed ACP on half of the models using RTGE (after digital planning) and CONV on the other half 2 weeks later. The time was recorded. Postoperative substance loss was measured by cone-beam computed tomographic imaging. The differences in time and substance loss between the methods and operators were evaluated by the t test. RESULTS: Overall, substance loss was significantly lower with RTGE than CONV (mean = 10.5 mm3 vs 29.7 mm3), but both procedures took a similar time per tooth (mean = 195 vs 193 seconds). Operator 1 (more experienced) achieved significantly less substance loss than operator 2 with CONV (mean = 19.9 vs 39.4 mm3) but not with RTGE (mean = 10.3 vs 10.6 mm3). CONCLUSIONS: RTGE is a practicable, substance-sparing method performed in comparable time as CONV. Moreover, RTGE seems to be independent of operator experience.

Apical Pressure Generated Using Conventional Syringe Irrigation in Immature Teeth-An In Vitro Study.

This in vitro study aimed to evaluate apical pressure during irrigant delivery with syringe irrigation in immature teeth with an open apical foramen. Conventional syringe irrigation was performed in a 3D-printed immature incisor. A 5 mL syringe combined with 25 G and 30 G cannulas was used. Open-ended and side-vented needle tip designs were assessed. Cannulas were placed at tooth length (TL), TL -1 mm, TL -2 mm, and TL -4 mm. The syringe plunger was moved with a force of 10 N, 20 N, 40 N, and 80 N to simulate clinical conditions. A pressure sensor measured periapical pressures during irrigation. Each experiment was repeated 10 times. Data were analyzed descriptively (maximum, mean, standard deviation, 95% CI) with the critical threshold indicative of extrusion set at 7.64 mbar. 30 G cannulas with both needle tip designs never exceeded the threshold at any TL with a plunger force of 10-40 N. At 80 N, 30 G open-ended cannulas exceeded the threshold in 10%, 30 G side-vented in 20-60% of the measurements. At any TL, 25 G open-ended cannulas and 25 G side-vented cannulas never crossed the threshold with forces of 10-20 N and 10 N, respectively. Consequently, 30 G cannulas with both designs can be recommended for irrigant delivery in immature teeth. 25 G cannulas ought to be used with caution.

Apical pressures generated by several canal irrigation methods: A laboratory study in a maxillary central incisor with an open apex.

AIM: A laboratory study to determine the apical pressure generated by seven canal irrigation methods in an anterior tooth with an open apex. METHODOLOGY: Canal irrigation was performed on a 3D-printed central maxillary incisor with an open apex (maximum diameter of 2.1 mm). Ultrasonically activated irrigation (UAI), sonic activation (EDDY), negative pressure irrigation (EndoVac), the self-adjusting file (SAF) and the XP-endo Finisher were employed at tooth length (TL), TL-1 mm, TL-2 mm and TL-3 mm. UAI was tested at three intensity levels additionally. Hydrodynamic irrigation with RinsEndo was performed in the pulp chamber, at the canal orifice, the coronal third, the middle of the canal and at TL. Er:YAG laser activation, at four frequency settings, was performed in the pulp chamber and at the orifice of the canal. The pressure of the fluid towards the canal terminus generated by activation was directly transferred to a pressure sensor with a range of 0 to 120 mmHg and a response time of ≤0.5 ms. The critical threshold for apical extrusion of the irrigant was set at 5.73 mmHg (lower limit of the central venous pressure: 5.88 ± 0.15 mmHg). Each experiment was repeated ten times. The tests were followed by descriptive analyses (maximum, mean, standard deviation, 95% confidence interval). RESULTS: EndoVac, the SAF, the XP-endo Finisher, and UAI never exceeded the critical threshold at any insertion depth or intensity level. Er:YAG laser activation exceeded the critical threshold exclusively at frequency settings that varied from the manufacturer's recommendation. EDDY at TL and RinsEndo at any insertion depth exceeded the critical threshold in 100% of the measurements. EDDY at TL-1,-2, and-3 mm crossed the critical threshold in 30%, 10%, and 20% of the measurements, respectively. CONCLUSIONS: In a simulated maxillary central incisor with an open apex, irrigation with EndoVac, Er:YAG laser activation, UAI, the SAF, and the XP-endo Finisher generated apical pressures below the critical threshold of 5.73 mmHg. By contrast, using EDDY and RinsEndo for irrigation produced higher apical pressures that exceeded the critical threshold.