Age Estimation in Brazilian Adults Using the Pulp/Tooth Ratio of the Maxillary Canine and Mandibular Second Premolar.

(1) Background/Objectives: Accurate determination of chronological age is crucial in legal dental identification. This study aimed to compare the effectiveness of different formulas in estimating the age of a Brazilian subpopulation by analyzing the pulp/tooth ratio of the maxillary canine and mandibular second premolar in panoramic and periapical radiographs. (2) Methods: The sample consisted of panoramic and periapical radiographs of 247 individuals. The file of each radiograph was opened in the Adobe Photoshop CS4® program to outline and obtain values in pixels for calculating the pulp/tooth ratio. Statistical analysis was conducted using the SPSS program, with a significance level set at 5%. (3) Results: The interclass correlation coefficient demonstrated excellent intra-observer agreement (0.990-0.999). The determination coefficients (R2) suggested that only 30-35% of the actual age results could be explained by the pulp/tooth ratio. The smallest differences were observed with Cameriere's formula for the mandibular second premolar on panoramic radiographs (+4.1 years). The greatest differences were found with the formulas for the mandibular second premolar in panoramic radiographs of the Korean (+12.5 years) and Portuguese (-12.1 years) populations. (4) Conclusions: The equations employed showed little agreement between the actual age and the estimated age.

Spatial Position and Anatomical Characteristics Associated with Impacted Third Molars Using a Map-Reading Strategy on Cone-Beam Computed Tomography Scans: A Retrospective Analysis.

(1) Background: This study assessed the spatial position and anatomical features associated with impacted third molars through a map-reading strategy employing cone-beam computed tomography (CBCT). (2) Methods: The positioning of impacted third molars on CBCT was assessed using Winter's and Pell and Gregory's classifications. External root resorption in mandibular second molars was categorized according to Herman's classification. Additionally, the relationship between the mandibular third molar root apex and the mandibular canal was examined. Comparative statistical analysis was conducted using Fisher's exact test, with a significance level considered as 5%. (3) Results: The results indicated that, based on Winter's classification, 48.06 % of impacted teeth were positioned mesioangularly. Employing Pell and Gregory's classification, 43.22% of the impacted molars fell into positions B and C, with 54.2% classified as Class II. A notable 69.7% of teeth exhibited no contact between the root apex and the mandibular canal, and external root resorption in the distal aspect of the second molar was absent in 88.7% of cases. (4) Conclusions: Utilizing the map-reading strategy with CBCT scans to assess the anatomical positions and characteristics of impacted third molars enhances professional confidence and sets a standard for quality and safety in the surgical procedure for patients.

Structural and torque changes in implant components of different diameters subjected to mechanical fatigue.

OBJECTIVES: To evaluate torque maintenance and structural damage in implant components of different diameters subjected to a fatigue challenge. METHODS: Thirty 10-mm-long, morse taper connection, titanium dental implants and their corresponding one-piece abutments were divided into three groups (n = 10) according to implant diameter: 4.3 mm (I4.3), 3.5 mm (I3.5), and 2.9 mm (I2.9). The implants were placed into a load-bearing fixture simulating bone tissue (modified G10), and the abutments were screwed into the implants to a final torque of 20 Ncm for the I4.3 and I3.5 and 15 Ncm for I2.9. The torque was secured by a digital torque meter. Cone-beam computed tomography (CBCT) scans were acquired and post-processed (e-Vol DX software) for all implant/abutment sets before and after subjecting them to fatigue in 37 °C distilled water (2 million cycles, constant load and frequency). The removal torque was measured using the same digital torque meter to calculate the difference in torque before and after fatigue. RESULTS: I2.9 showed substantial structural deformation compared with the other implant diameters (I3.5 and I4.3). However, the experimental groups did not show statistical differences for abutment loosening. SIGNIFICANCE: Implants smaller than 3.5 mm in diameter have a higher probability of structural deformation than standard-diameter implants. The association between tomographic scans and e-Vol DX software showed satisfactory consistency with the direct assessment using the digital torque meter, offering an additional tool to evaluate implant component loosening and structural deformations.

Method to determine the root canal spatial geometry using an algorithm of the e-Vol DX CBCT software.

This study evaluated a method to determine the spatial geometry of root canal preparation (RCP) using navigation dynamics and a specific algorithm from a new CBCT software (e-Vol DX). CBCT scans of 168 root canals of mandibular molars were acquired before and after RCP, using nickel-titanium (NiTi) instruments (ProTaper Next, BioRace, Reciproc Blue, and WaveOne Gold). The spatial geometry of the root canals and the operative risk of disproportional wear of dentinal walls after RCP were evaluated using a new CBCT software. A 3-point scoring system was used after the measuring of cementum/dentin thickness before and after RCP in all root thirds. The root thirds were distributed into three parts of similar sizes, and the scores were categorized at three levels: 1. mild risk (1/3), 2. moderate risk (2/3), 3. severe risk (3/3). These levels were proposed according to the risk of creating disproportionate shapes, thin walls, or perforations. The data were analyzed statistically by Fischer's exact test (α = 5%). There were no significant differences in operative risk among the NiTi engine-driven systems, for the distal or mesial walls of all the root canal thirds (p>0.05). The spatial geometry method to assess operative risk allows clinical planning for a predictable enlargement of the root canal in all root thirds. Based on using a map-reading strategy on root canals in CBCT scans, NiTi engine-driven instruments did not present an increased operative risk during RCPs.

Impact XP-endo finisher on the 1-year follow-up success of posterior root canal treatments: a randomized clinical trial.

OBJECTIVE: To evaluate the clinical relevance of using the XP-endo Finisher as a supplementary tool to improve the success of root canal treatment of posterior teeth with apical periodontitis, as assessed by 1-year follow-up. METHODS: A randomized clinical trial was conducted with 92 posterior teeth with apical periodontitis. Root canal treatment was performed using a single reciprocating file, with or without the supplementary use of the XP-endo Finisher. The status of apical periodontitis was assessed using the periapical index (PAI) at baseline and 1 year follow-up. Changes on PAI indicated that the lesions were healed, healing, or not healed. Successful treatments were defined as healed or healing lesions without clinical symptoms. Chi-square analysis and logistic regression were used for data analysis (α = 0.05). RESULTS: There was no significant difference in the distribution of healing status between the XP-endo Finisher group and the control group (p = 0.690). The success rates were also similar, with 81% in the XP-endo Finisher group and 78% in the control group. However, gender had a significant impact on success rates, with higher rates observed in females. CONCLUSIONS: The use of the XP-endo Finisher file as a supplementary tool did not affect the success rate of root canal treatment in posterior teeth with apical periodontitis. The findings indicate that the XP-endo Finisher file has limited clinical relevance in improving treatment outcomes for root canal treatment in posterior teeth with apical periodontitis. CLINICAL TRIAL REGISTRATION: The study protocol was registered in the Brazilian Clinical Trials Registry under identification number RBR-76w7cj (June 19, 2018).

Comparison of Curvature Severity Between Sagittal and Coronal Planes of Mesiobuccal Canals in Permanent Maxillary First Molars Using Multiple Complexity-risk Criteria: A CBCT Cross-sectional Study of a Brazilian Subpopulation.

INTRODUCTION: This study aimed to compare the curvature severity of mesio-buccal (MB) canals between sagittal and coronal planes using cone-beam computed tomography. METHODS: In a Brazilian subpopulation, untreated MB1 (n = 141) and MB2 (n = 72) with single curvatures in sagittal and coronal planes were measured to determine their angle and radius (r), plus the prevalence of S-shaped canals was recorded. Curvature severity was defined according to the American Association of Endodontists Case Difficulty Assessment form (AAE) and EndoApp (EA), as well as their modified versions that consider angle and radii (AAE-r, EA-r). Data were converted into mean angle and r, percentage of canals >30°, AAE, EA, AAE-r and EA-r categories. The influence of r on case severity was assessed. Statistical analysis was performed using t-tests and chi-squared tests. The level of significance was set as P ≤ .05. RESULTS: For single curvatures, significantly higher mean degrees (SD) angles were found in the sagittal views in both canals (MB1 sagittal: 35 [11]; MB1 coronal: 13 [13]; MB2 sagittal: 29 [14]; MB2 coronal: 22 [15] [P < .05]). A greater percentage of angles >30° (MB1: 56.7% vs 6.4%; MB2: 44.4% vs 22.2%) in sagittal planes compared to coronal planes was also found. Conversely, a higher prevalence of S-shaped canals (MB1: 33.3% vs 7.1% MB2: 31.9% vs 15.3%) was observed in coronal planes. Significant differences between AAE and AAE-r were present with greater case severity when radii were considered (P < .05). CONCLUSIONS: Sagittal planes were associated with more severe single curvatures, while coronal planes had a greater prevalence of S-shaped canals.

Does radiotherapy treatment alter the pulp condition in patients with head and neck cancer? A systematic review.

The main purpose of this study was to answer the question: "Can radiotherapy cause changes in the dental pulp condition of patients treated with irradiation in the head and neck region?" Clinical observational studies in adults with head and neck cancer undergoing treatment with ionizing radiation, longitudinal or cross-sectional follow-up to measure oxygen saturation (SpO2), and/or pulp sensitivity test to cold stimulation, were considered eligible. A systematic literature search was performed in six different databases, including the gray literature, and in article references. Two independent evaluators selected the studies, extracted the data, recorded the data on electronic spreadsheets, and then evaluated the methodological quality using the Checklist for Quasi-Experimental Studies tool devised by JBI. The data were assessed qualitatively using the Synthesis Without Metanalysis (SWiM) guidelines. After removing the duplicate articles, carefully analyzing the titles and abstracts, and reading the papers in full, seven studies were included. Four of the studies evaluated applied the cold sensitivity test, two associated pulse oximetry and cold sensitivity, and only one used just pulse oximetry. Evaluation using the cold sensitivity test and pulse oximetry in the initial periods before radiotherapy showed a decrease in the sensitive response and in SpO2 levels during a maximum period of 1 year. However, analyses thereafter indicated a normal response in both tests from 5 to 6 years after the end of radiotherapy treatment. Radiotherapy causes changes in pulp behavior patterns in the short term; however, recovery and return to average values occurs after long periods.

The effect of ultrasonic vibration protocols for cast post removal on the incidence of root dentin defects.

PURPOSE: To investigate the effects of two ultrasonic vibration protocols for cast post removal (single or double ultrasound units) on the development of defects in root dentin. METHODS: Sixty bovine incisors were selected. Fifteen roots were left unprepared (control). Forty-five roots were instrumented and filled. A 10-mm post space was prepared using #1-4 Largo drills. Fifteen teeth were prepared for post space and received no further procedure. Thirty roots had cast posts cemented and were submitted to ultrasonic vibration protocols for removal. The time necessary to remove each post was recorded. Roots were sectioned 3, 6, 9, and 12 mm from the coronal portion and viewed through a 25× magnification in a stereomicroscope. The presence of root fractures, partial cracks, and craze lines was registered. Chi-square and Fisher's exact tests were performed to compare the incidence of dentin defects. The Kruskal-Wallis test was performed to explore the difference between the time needed for post removal. The significance level was set at P = 0.05. RESULTS: Root defects were observed in all experimental groups. There were no statistical differences comparing previous root canal treatment and post removal steps, either with 1 or 2 ultrasonic units, in the formation of defects (P = 0.544) or fractures (P = 0.679). CONCLUSION: Ultrasonic vibration protocols for removing cast posts did not increase the number of dentin defects compared to root canal preparation and obturation and post space preparation steps.

Evaluation of Serum Levels of Cytokines in Acute Apical Abscess: A Longitudinal Observational Study.

INTRODUCTION: Cytokine levels are related to the aethiopathogenia of acute apical abscesses (AAA); however, the specific cytokine profiles in these cases are unclear. This study aimed to investigate the changes in systemic cytokine levels in patients with AAA and trismus onset, postantibiotic treatment, and postroot canal disinfection. METHODS: In total, 46 AAA patients with trismus and 32 control subjects were included. After seven days of antibiotic therapy, root canal disinfection was performed in the AAA patients. The serum levels of cytokines were evaluated at basal, seven, and 14 days after endodontic treatment. Quantification of cytokines from T helper (Th) 1, Th2, Th17, and regulatory T cells profiles was determined using the BioPlex MagPix system, and the obtained data were analyzed using SPSS statistical software (P < .05). RESULTS: AAA patients showed higher tumor necrosis factor-alpha (TNF-α), interleukin (IL) -6, and IL-10 levels than control subjects, at basal measurement (P < .05); there were similar levels of interferon gamma, IL-1ß, IL-4, and IL-17 between groups (P > .05). IL-6 and IL-10 levels decreased after antibiotic treatment (P < .05), which was also associated with clinical improvement in patients with AAA and trismus. Patients with AAA had a positive correlation with higher serum levels of IL-6 and IL-10. In addition, TNF-α levels decreased only after antibiotic and endodontic treatment. CONCLUSIONS: In conclusion, patients with AAA had increased systemic serum levels of TNF-α, IL-6, and IL-10. Moreover, increased levels of IL-6 and IL-10 are associated with acute inflammatory symptoms. However, IL-6 and IL-10 levels decreased after antibiotic treatment, while TNF-α levels decreased after antibiotic and endodontic treatment.

Influence of a Metal Artifact Reduction Filter on the Diagnostic Accuracy of Complete and Incomplete Vertical Root Fractures.

INTRODUCTION: This study aimed to assess the influence of the e-vol DX BAR filter on the diagnostic accuracy of complete and incomplete vertical root fractures (VRFs). METHODS: Twenty single-rooted teeth were selected. The tooth crowns were removed, and the root canals were prepared up to a 40/.06 instrument (ProTaper Next). Each specimen was scanned in a Prexion 3D cone-beam computed tomography (CBCT) device, in a dry human skull, in 4 different situations: no root canal filling, gutta-percha, fiberglass post, and metal post. The specimens were fractured in a universal testing machine by using a customized wedge. Each specimen was reinspected to confirm the presence of incomplete VRFs. Another set of CBCT scans was performed. Then, the fractures were completed in the universal testing machine, the teeth were reinspected, and the CBCT images were acquired again. Images were assessed by using the e-Vol DX software system, with the BAR filter and with the original images, for the diagnosis of VRFs. Statistical analysis was performed by using the DeLong and McNemar tests for the comparison of the area under the receiver operating characteristic curves (AUC), accuracy, sensitivity, and specificity values. RESULTS: The use of the BAR filter did not improve the diagnostic values of AUC, accuracy, sensitivity, and specificity in both fracture patterns (P > .05). Incomplete VRFs presented significantly lower AUC, accuracy, and sensitivity compared with complete VRFs (P < .0001). CONCLUSIONS: The BAR filter did not improve the diagnostic accuracy of VRFs. The intracanal materials also did not influence the diagnosis. Incomplete VRFs were highly associated with a decrease in sensitivity.

Surface wear and adhesive failure of resin attachments used in clear aligner orthodontic treatment.

PURPOSE: This study evaluated adhesive and cohesive failures and the surface wear of attachments employed in clear aligner treatment (CAT) using three-dimensional (3D) superimposition. METHODS: In all, 3D models of 150 teeth were obtained from intraoral scans from patients undergoing CAT with at least 4 months between each scan. Of the initial sample, 25 teeth were discarded, and 125 teeth were included in the study. Superimpositions of each individual tooth at the first and second time points were made using computer-aided design (CAD) software (Meshmixer; Autodesk, Mill Valley, CA, USA). Analyses were performed to compare surface wear and failures related to type of attachment (optimized/conventional), dental group (molars/premolars/anterior teeth), and arch (mandibular/maxillary). Mann-Whitney and Kruskal-Wallis statistical tests were applied with significance set at 5%. RESULTS: More surface wear was observed in conventional attachments, mandibular and anterior teeth with statistical significance for surface wear on the distal surface of conventional attachments (p < 0.05). Cohesive failure was observed in 10% of attachments, occurring most frequently on optimized attachments and molar teeth. Adhesive failure was observed in 10% of the samples, more frequently on conventional attachments and posterior teeth. CONCLUSION: Attachment type (conventional vs. optimized) was significantly correlated with surface wear on the distal surface of the attachment. Arch (mandibular or maxillary) and group of teeth (anterior or posterior) showed no correlation with surface wear. Failure, both adhesive and cohesive, correlated with attachment type and group of teeth, but not with the arch in which they were located.

Does irradiation of the tooth structure interfere with oxygen saturation measured by pulse oximetry?-An ex vivo laboratorial study.

The effect of tooth structure subjected to ionising radiation on oxygen saturation levels (SpO2 ) measured by pulse oximetry was investigated. Fifty-four extracted human third molars were sectioned mesiodistally. Pulse oximeter diodes were placed in prefabricated silicone moulds, secured on a vise with tooth surfaces placed between the diodes and the participant's finger, and SpO2 levels were measured. After that, the tooth surfaces were subjected to ionising radiation in fractionated doses of up to 70 Gy, and SpO2 was measured according to the protocol described. The Kolmogorov-Smirnov test was used for the analysis of normality of the quantitative variables, and Student's t-test compared mean SpO2 levels before and after irradiation. Mean SpO2 after irradiation was 94.6 ± 0.9%, without a statistically significant difference from SpO2 before irradiation, which was 94.7 ± 0.6%. Irradiation of the tooth structure did not interfere with SpO2 levels measured by pulse oximetry.

Mechanism of action of Bioactive Endodontic Materials.

A continuous search for bioactive materials capable of supporting the replacement of damaged pulp tissue, with effective sealing potential and biocompatibility, has represented the attention of studies over the last decades. This study involves a narrative review of the literature developed by searching representative research in PUBMED/MEDLINE and searches in textbooks associated with the mechanism of action of bioactive materials (calcium hydroxide, mineral trioxide aggregate (MTA), and calcium silicate cements). The reflective analysis of the particularities of the chemical elements of these materials, considering the tissue and antibacterial mechanism of action, allows a better understanding of the characteristics and similarities in their tissue responses. Calcium hydroxide paste remains the antibacterial substance of choice as intracanal dressing for the treatment of root canal system infections. Calcium silicate cements, including MTA, show a favorable biological response with the stimulation of mineralized tissue deposition in sealed areas when in contact with connective tissue. This is due to the similarity between the chemical elements, especially ionic dissociation, the potential stimulation of enzymes in tissues, and the contribution towards an alkaline environment due to the pH of these materials. The behavior of bioactive materials, especially MTA and the new calcium silicate cements in the biological sealing activity, has been shown to be effective. Contemporary endodontics has access to bioactive materials with similar properties, which can stimulate a biological seal in lateral and furcation root perforations, root-end fillings and root fillings, pulp capping, pulpotomy, apexification, and regenerative endodontic procedures, in addition to other clinical conditions.

Effect of intra-radicular cleaning protocols after post-space preparation on marginal adaptation of a luting agent to root dentin.

PURPOSE: To evaluate the effect of intra-radicular cleaning protocols after post-space preparation (PSP) on marginal adaptation of a luting agent to root dentin. METHODS: Eighty bovine incisors were sectioned transversely to obtain 18-mm-long root sections. The roots were prepared with ProTaper instruments and filled using Tagger's hybrid technique. PSP was performed at a length of 14 mm using #3-5 Largo drills. The roots were distributed into eight groups according to the chelating solution used (17% EDTA or 0.2% Chitosan) and the chelating activation/delivery method employed (conventional needle irrigation [CNI], EndoActivator [EA], XP-Endo Finisher [XPF] or passive ultrasonic irrigation [PUI]). The fiber posts were cemented using self-adhesive resin cement, and the roots were sectioned to obtain three discs from each root third. The dentin discs were observed under an optical microscope at ×40 magnification to assess marginal adaptation. The different protocols were compared considering the frequency of the marginal adaptation scores using the Kruskal-Wallis test, followed by the Dwass-Steel-Critchlow-Fligner test (α = 5%). RESULTS: The use of 17% EDTA resulted in better marginal adaptation (P < 0.001). PUI yielded results that were similar to those for EA (P = 0.949) and superior to those for XPF (P = 0.020). The combination of 17% EDTA + PUI provided a greater number of interfaces without marginal gaps (P < 0.001). CONCLUSION: The cleaning protocol influenced the marginal adaptation of resin cement to root dentin.

Evaluation of the expression of nerve fiber markers in healthy and inflamed dental pulp.

The diagnosis of irreversible pulpitis (IP) depends on clinical data, especially the chief complaint of the patient, visual inspection, response to the application of stimuli, and radiographic examination. The characterization of nerve fibers (NF) in IP may contribute to better interpret painful symptoms, but has been barely explored. This study sought to characterize the density and integrity of NF in 16 samples of IP and in five healthy pulps (HP) using S-100 and PGP 9.5 markers. Immunohistochemistry was performed to determine the density/mm2 of S-100+ and PGP 9.5+ in NF. The amount of degenerated NF was obtained by subtracting the total NF density from the amount of intact NF. Associations between NF density and integrity and symptomatology were calculated. All samples were positive for S-100 and PGP 9.5. Compared to HP samples (38.20/mm2), IP samples had a lower density of intact NF (6.24/mm2). A significantly higher density of degenerated NF was found in IP samples with spontaneous pain (39.59/mm2) compared to those with provoked pain (23.96/mm2) (p = 0.02). No association was observed between intensity of the inflammatory infiltrate and NF density and integrity (p > 0.05). The findings of this study suggest that pulpitis may involve different stages of degeneration and may be more advanced in cases with spontaneous pain. The symptoms reported by affected individuals do not appear to depend on the intensity of the inflammatory infiltrate, but rather on the integrity of NF.

Mechanism of action of Bioactive Endodontic Materials

Abstract A continuous search for bioactive materials capable of supporting the replacement of damaged pulp tissue, with effective sealing potential and biocompatibility, has represented the attention of studies over the last decades. This study involves a narrative review of the literature developed by searching representative research in PUBMED/MEDLINE and searches in textbooks associated with the mechanism of action of bioactive materials (calcium hydroxide, mineral trioxide aggregate (MTA), and calcium silicate cements). The reflective analysis of the particularities of the chemical elements of these materials, considering the tissue and antibacterial mechanism of action, allows a better understanding of the characteristics and similarities in their tissue responses. Calcium hydroxide paste remains the antibacterial substance of choice as intracanal dressing for the treatment of root canal system infections. Calcium silicate cements, including MTA, show a favorable biological response with the stimulation of mineralized tissue deposition in sealed areas when in contact with connective tissue. This is due to the similarity between the chemical elements, especially ionic dissociation, the potential stimulation of enzymes in tissues, and the contribution towards an alkaline environment due to the pH of these materials. The behavior of bioactive materials, especially MTA and the new calcium silicate cements in the biological sealing activity, has been shown to be effective. Contemporary endodontics has access to bioactive materials with similar properties, which can stimulate a biological seal in lateral and furcation root perforations, root-end fillings and root fillings, pulp capping, pulpotomy, apexification, and regenerative endodontic procedures, in addition to other clinical conditions.

Resumo Uma busca contínua de materiais bioativos com capacidade de substituir o tecido pulpar danificado, com efetiva capacidade de selamento e biocompatibilidade, tem representado a atenção e foco de muitos estudos ao longo das últimas décadas. Este estudo envolve uma revisão narrativa da literatura desenvolvida por meio de pesquisas representativas encontradas no PUBMED/MEDLINE e pesquisas em livros didáticos associadas ao mecanismo de ação de materiais bioativos (hidróxido de cálcio, agregado de trióxido mineral (MTA) e cimentos de silicato de cálcio). A presente análise reflexiva das particularidades dos elementos químicos destes materiais bioativos, considerando o mecanismo de ação tecidual e antibacteriano, possibilita um melhor entendimento das características e similaridades no comportamento tecidual. A pasta de hidróxido de cálcio continua sendo a substância antibacteriana de escolha como medicação intracanal para o tratamento das infecções do sistema de canais radiculares. Este fato se deve a disponibilidade química de íons cálcio e hidroxila do hidróxido de cálcio aos tecidos, e a inibição enzimática bacteriana. Os cimentos de silicato de cálcio, dentre os quais inclui o MTA, apresentam uma resposta biológica favorável ao estímulo à deposição de tecido mineralizado nas áreas seladas e em contato com tecido conjuntivo. Este fato é decorrente da similaridade entre os elementos químicos, em especial devido a dissociação iônica, ao potencial estímulo de enzimas teciduais, e a contribuição com um meio alcalino decorrente do pH destes materiais. O comportamento dos materiais bioativos, em especial o MTA e os novos cimentos de silicato de cálcio na atividade de selamento biológico mostraram efetivos. A endodontia contemporânea atualmente conta com o potencial de materiais bioativos com propriedades análogas capaz de estimular o selamento biológico em perfurações radiculares laterais e de furca, em obturações radiculares, capeamento pulpar, pulpotomia, apicificação e procedimentos endodônticos regenerativos, além de outras condições clínicas.

Development and validation of a method for creating incomplete vertical root fracture in extracted teeth.

The present study reported a method for inducing incomplete root fracture in human extracted teeth for the purpose of evaluating the merits of different diagnostic imaging techniques. Thirty-five single-rooted teeth were inspected under magnification and transillumination to exclude previously fractured teeth. Tooth crowns were removed, and the root canals were prepared up to the ProTaper Next X4 (40.06) file. Each root was lined with wax and embedded in a polystyrene resin block. The setup was attached to a universal testing machine for pressing a customized conical wedge (diameter at tip: 0.6 mm; taper: 0.2 mm/mm) into the instrumented canal with a 2 kN load at 5 mm/min. The machine was programmed to stop after a sudden 10% drop in loading force. Each specimen was removed from the resin block and inspected under × 20 magnification and transillumination to identify the fracture characteristics (pattern, surfaces and root-third affected). The gap width of each specimen was measured at different locations along the fracture line. The protocol induced incomplete vertical root fractures in all specimens. Fracture widths were < 100 µm in all specimens (mean gap width: 34.9 µm). The proposed methodology was successful in inducing incomplete vertical root fractures with characteristics that resemble the clinical presentation of these conditions. The method is easy to execute, highly reproducible and helps to minimize bias in laboratory studies that aims to mimic vertical root fractures.

Guided Access Cavity Preparation Using a New Simplified Digital Workflow.

INTRODUCTION: This study evaluated the precision of a simplified workflow using only preoperative cone-beam computed tomographic (CBCT) scans to gain guided access to root canals of extracted mandibular molars. A workflow using CBCT scanning associated with 3-dimensional oral scanning was used as a reference for comparison. The influence of the presence of coronal restoration in the simplified workflow was also evaluated. METHODS: Forty-five mandibular molars were randomized into 3 groups: a control group in which digital planning was performed with CBCT and oral scanning and 2 experimental groups in which digital planning was performed only with CBCT examination. In experimental group 1, teeth had no coronal restorations, whereas in group 2 teeth presented with coronal composite restorations. After digital planning, the teeth were accessed using the guides, and a new CBCT scan was made to overlap the pre- and postoperative examinations. Precision was measured by calculating the deviation between the planned and prepared cavities in millimeters and angle. Data were compared using 1-way analysis of variance (P < .05). RESULTS: All root canals were accessible after access preparation in all tested groups. Deviations of the planned and prepared access cavities were low, with a mean value of 0.55, 0.58, and 0.47 mm and 1.98°, 2.45°, and 1.43° for the control group, group 1, and group 2, respectively. No significant differences in millimeters or angle were observed among the 3 tested groups (P > .05). CONCLUSIONS: The simplified digital workflow using only CBCT examination allowed a high level of precision in obtaining access in extracted molars with and without coronal restoration, presenting similar results compared with the digital workflow using CBCT and 3-dimensional oral scanning.

Method to determine the root canal spatial geometry using an algorithm of the e-Vol DX CBCT software

Abstract This study evaluated a method to determine the spatial geometry of root canal preparation (RCP) using navigation dynamics and a specific algorithm from a new CBCT software (e-Vol DX). CBCT scans of 168 root canals of mandibular molars were acquired before and after RCP, using nickel-titanium (NiTi) instruments (ProTaper Next, BioRace, Reciproc Blue, and WaveOne Gold). The spatial geometry of the root canals and the operative risk of disproportional wear of dentinal walls after RCP were evaluated using a new CBCT software. A 3-point scoring system was used after the measuring of cementum/dentin thickness before and after RCP in all root thirds. The root thirds were distributed into three parts of similar sizes, and the scores were categorized at three levels: 1. mild risk (1/3), 2. moderate risk (2/3), 3. severe risk (3/3). These levels were proposed according to the risk of creating disproportionate shapes, thin walls, or perforations. The data were analyzed statistically by Fischer's exact test (α = 5%). There were no significant differences in operative risk among the NiTi engine-driven systems, for the distal or mesial walls of all the root canal thirds (p>0.05). The spatial geometry method to assess operative risk allows clinical planning for a predictable enlargement of the root canal in all root thirds. Based on using a map-reading strategy on root canals in CBCT scans, NiTi engine-driven instruments did not present an increased operative risk during RCPs.

Resumo Este estudo avaliou um método para determinar a geometria espacial do preparo do canal radicular (PCR) usando uma dinâmica de navegação e um algoritmo específico do software e-Vol DX. Imagens de tomografia computadorizada de feixe cônico (TCFC) de 168 molares inferiores foram adquiridas antes e depois do PCR, usando instrumentos de níquel-titânio (NiTi) (ProTaper Next, BioRace, Reciproc Blue e WaveOne Gold). A geometria espacial dos canais radiculares e o risco operatório de desgaste desproporcional das paredes dentinárias após o preparo foram avaliados usando o software de TCFC e-Vol DX. Um sistema de Score de 3 pontos foi usado após a mensuração da espessura cemento/dentina antes e depois do PCR, em toda extensão dos canais radiculares. Os terços radiculares foram distribuídos em três partes de tamanhos semelhantes, e os Scores foram categorizados em três níveis: 1. risco leve (1/3), 2. risco moderado (2/3), 3. risco severo (3/3). Esses níveis foram propostos de acordo com o risco de criar formas desproporcionais, paredes finas ou perfurações radiculares. Os dados foram analisados estatisticamente pelo teste exato de Fischer ((=5%). Não houve diferenças significativas no risco operatório entre os sistemas de NiTi acionados a motor, para as paredes distal ou mesial em todos os terços do canal radicular (p>0,05). O método de geometria espacial para avaliar o risco operatório permite o planejamento clínico para um alargamento previsível do canal radicular em todos os terços radiculares. Com base no uso de uma estratégia de navegação dinâmica de canais radiculares de molares inferiores analisados em imagens de TCFC, os instrumentos de NiTi acionados estudados não apresentaram um aumento do risco operatório durante o preparo dos canais radiculares.