Vertical Root Fracture Research Articles

Accuracy of cone-beam CT in detecting vertical root fractures in teeth with post-endodontic restorations: an in vitro study

The aim of this study was to evaluate the accuracy of cone-beam CT (CBCT) for the detection of artificially created vertical root fractures (VRF) in extracted teeth restored with metallic (MP) and fiberglass (FGP) posts. After root canal obturation, 60 extracted human premolars were scanned by using the highest-resolution settings of a CBCT unit. The prepared roots were randomly divided into three groups: group C (control group): non-restored and non- endodontically treated teeth (n = 20); group MP (n = 20); group FGP (n = 20). In all groups, 10 teeth were artificially fractured. Two external and independent observers blindly recorded the presence or absence of VRF. Sensitivity, specificity, accuracy, intra- and interobserver agreement were calculated. Kappa value for inter- and intraobserver agreement was 0.82 and 0.84 respectively, demonstrating good agreement. The highest values for sensitivity (0.80 - 0.90), specificity (1.00) and accuracy (0.90 - 0.95) were found in the control group. The teeth with FGP restoration presented the lowest sensitivity (0.30 - 0.50) and accuracy (0.60 - 0.65) values. Both examiners had a good performance in the diagnosis of fractures in teeth with MP, with accuracy ranging between 0.85 - 0.90. The presence of MP did not influence accuracy; however, the presence of FGP reduced the diagnostic capacity of CBCT.

Digital file format does not influence the radiographic diagnosis of vertical root fracture.

ObjectiveTo evaluate the influence of the file format of digital periapical radiographs on the diagnosis of vertical root fracture (VRF).Study designPeriapical radiographic images of 34 single-rooted teeth—19 with VRF, and 15 without VRF were acquired using two digital systems—Digora Toto, and Digora Optime, and exported into four different file formats—TIFF, BMP, PNG, and JPEG, totaling 272 radiographs. The radiographs were assessed by five examiners for the detection of VRF, using a 5-point scale (1—definitely absent; 2—probably absent; 3—uncertain; 4—probably present; 5—definitely present). Diagnostic values of area under the ROC curve, specificity, and sensitivity for the diagnosis of VRF were calculated. The results were compared by two-way Analysis of Variance with post hoc Tukey’s test. The intra- and inter-examiner agreements were measured by the Kappa test. The significance level was set at 5% for all analyses.ResultsThe values of intra-examiner agreement varied from moderate (0.56) to almost perfect (0.81), while the values of inter-examiner agreement varied from fair (0.29) to moderate (0.60). The image file format did not influence the diagnostic values for VRF for any of the radiographic systems tested (p > 0.05). Digora Toto had significantly greater values of area under the ROC curve than Digora Optime for all file formats (p = 0.001).ConclusionThe image file format of periapical radiographs does not influence the diagnosis of VRF, regardless of the digital radiography system.

Clinical analysis on the root fracture of the maxillary first molar.

This study aimed to investigate the common types and directions of root fractures of the maxillary first molar and the influence of root canal treatment on the prevalent sites of root fractures. A total of 274 maxillary first molars with root fractures diagnosed via cone beam computed tomography were included. The root fractures of nonendodontically and endodontically treated teeth were identified to be spontaneous and secondary root fractures, respectively. The sites, types, and directions of spontaneous and secondary root fractures were determined. Among the spontaneous root fractures, the proportion of palatal root fractures (56.1%) was higher than those of mesial buccal root fractures (36.1%) and distal buccal root fractures (7.8%). Among the secondary root fractures, the proportion of mesial buccal root fractures (52.7%) was higher than those of palatal root fractures (36.5%) and distal buccal root fractures (10.8%). The distribution of predominant fracture sites was statistically significant (P<0.05), and vertical root fracture was the most common type. Palatal and buccal roots were commonly fractured at the mesiodistal and buccal-palatal directions, respectively. This study provided an epidemiological basis for the clinical features of root fractures of the maxillary first molar. During the dia-gnosis and treatment of the maxillary first molar, the possibility of palatal root fractures should be considered. The occurrence of mesial buccal root fractures may be related to root canal treatment. Therefore, the risk of mesial buccal root fractures caused by iatrogenic factors should be minimized.

Impact of different instruments metallurgy on Apical extrusion of debris and fracture resistance: A comparative invitro study

Abstract: The purpose of this research was to compare apical debris extrusion and fracture resistance of teeth prepared with OneCurve, WaveOne Gold, or ProTaper Universal. Materials and Methods: Mandibular premolars were prepared with OneCurve, WaveOne Gold, or ProTaper Universal. In the experimental model, debris was recovered by apical section of the root washing with distilled water. The Eppendorf tubes were weighed after 15 days of storage to establish the overall weight of the tubes, including the extruded debris. The dry weight of the ejected material was then computed. After root canal obturation, the apical root ends were trapped in the acrylic up to 2 mm below the cementoenamel junction. The fracture force was calculated and given in Newtons. A one-way ANOVA test was used to compare more than two groups, followed by a Tukey post hoc test. The significance level was set at P≤ 0.05. Results: The results revealed a statistically significant difference in extruded debris between OneCurve, WaveOne Gold, and ProTaper Universal (P <0.05), as well as a statistically significant difference in the load required for vertical root fracture between the negative control and OneCurve, WaveOne Gold, and ProTaper Universal (P <0.05). Conclusion WaveOne Gold had the lowest weight value of debris extrusion, whereas ProTaper Universal had the most. Negative control had the highest load, followed by WaveOne gold and One Curve, and finally ProTaper Universal.

Cone beam CT optimisation for detection of vertical root fracture with metal in the field of view or the exomass

Dose optimisation has been revisited in the literature due to the frequent use of cone beam computed tomography (CBCT). Although the reduction of the field-of-view (FOV) size has shown to be an effective strategy, this indirectly increases the negative effect from the exomass. The aim of this study was to evaluate the diagnostic accuracy of an optimised CBCT protocol in the detection of simulated vertical root fracture (VRF) in the presence of metal in the exomass and/or inside the FOV. Twenty teeth were endodontically instrumented and VRF was induced in half of them. All teeth were individually placed in a human mandible covered with a soft tissue equivalent material, metallic materials were placed at different dispositions in the exomass and/or endomass, and CBCT scans were obtained at two dose protocols: standard and optimised. Five radiologists evaluated the images and indicated the presence of VRF using a 5-point scale. Area under the ROC curve (AUC), sensitivity, and specificity were calculated and compared using ANOVA (α = 0.05). Overall, AUC, sensitivity, and specificity did not differ significantly (p > 0.05) between the dose protocols. In conclusion, optimised dose protocols should be considered in the detection of simulated VRF irrespective of the occurrence of artefacts from metallic materials in the exomass and/or inside the FOV.

Influence of Root Canal Sealers and Obturation Techniques on Vertical Root Fracture Resistance. An In Vitro Experiment

The aim of the present study was to determine the vertical root fracture (VRF) resistance of roots obturated with TotalFill BC Sealer and AH Plus sealer using lateral condensation and single cone techniques in comparison to untreated controls. Sixty single rooted mandibular premolars were sectioned and divided into six groups. Ten teeth were left untreated (positive control-Gp 1) and fifty teeth were cleaned and shaped. Ten root specimens were left unfilled (negative control-Gp 2) and the remaining roots were divided into 4 groups. Gp 3, GP and AH Plus sealer (AH Plus) using the cold lateral compaction (LC) technique; Gp 4, GP and AH Plus using the Single Cone (SC) technique; Gp 5: TotalFill GP and TotalFill BC sealer using the LC technique; Gp 6: TotalFill GP and TotalFill BC sealer with SC. VRF was performed for all specimens using a universal testing machine. Analysis of variance (ANOVA) and Tukeys post-hoc multiple comparison test was used to compare the means among tested study groups. Group 1 (positive control) displayed the highest fracture resistance (946.61 ± 166.465 N); however, the lowest fracture strength was demonstrated by the specimens in group 2 (negative control) (433.31 ± 129.350 N). Specimens treated with AH plus using different obturation techniques (group 3 and 4) showed comparable outcomes (p &gt; 0.05). Similarly, specimens treated with TotalFill BC sealer with different obturation techniques showed statistically similar outcomes (p &gt; 0.05). It was also observed that specimens in groups 3, 4, 5 and 6 demonstrated comparable outcomes of fracture strength (p &gt; 0.05). The use of TotalFill-BC sealer showed similar vertical root fracture resistance as AH plus sealer in root canal treated teeth. Use of total fill-BC and AH Plus sealer in root canal treatment showed vertical root fracture resistance comparable to untreated natural teeth (positive controls).

Detection of vertical root fractures in the presence of artefacts by digital radiography and cone beam computed tomography

The correct diagnosis of vertical root fractures (VRF) in the presence of artifacts is a challenge for clinicians and endodontists. Moreover, there is controversy about which imaging technique is best for this purpose. In an in vitro model, we evaluated the diagnosis of VRF in teeth treated endodontically with and without intraradicular metal posts, using the Clark technique and cone beam computed tomography (CBCT), as well as the interference of artifacts with the diagnosis. Twenty-two first or second maxillary or mandibular premolars were included. Teeth were randomly allocated to three groups: G1 (two teeth without fracture with endodontic treatment and one with an intraradicular metal post); G2 (10 fractured teeth with endodontic treatment); and G3 (10 fractured teeth with endodontic treatment plus a metal post). The examiners recorded the presence or absence of fracture and its location and classified its type. There was no statistically significant difference between image acquisition systems. When differentiating the teeth (first vs. second premolars), there was a statistically significant difference among the examiners (p=0.020). However, when comparing the values obtained by the examiners regarding the visualization of the fracture site as well as the presence of fracture correlated with the presence of a metal post and angulation, there were no statistically significant differences (p&gt;0.05). Digital radiographs and CBCT were similar for the diagnosis of VRF. High sensitivity was observed by CBCT image reconstructions. Therefore, the presence of metal posts generated artifacts, resulting in low sensitivity, specificity and accuracy.

CEMENTAL TEAR: REAL OR FICTION? A REVIEW OF THE LITERATURE AND THREE CASES

<h3>BACKGROUND</h3> Cemental tears are a form of root surface fracture caused by partial or total separation of cementum from the root surface.^1-4 Common clinical findings include deep periodontal pockets, gingival swelling, and pain. Owing to the overlapping clinical signs and symptoms with apical periodontitis, vertical root fracture, and periodontitis, cemental tears are often misdiagnosed and inappropriately treated. Their true prevalence remains unknown; however, many suspect that they occur more commonly than previously thought. <h3>CASE REPORT</h3> We report 3 patients examined at the University of Toronto. Two patients presented with draining fistulas and deep probing depths, and the third patient presented with a buccal vestibular swelling. Imaging examinations revealed a well-defined, linear, radiopaque/high-attenuation focus partially attached to or within close proximity to the adjacent root surface. The radiologic differential interpretation of the radiopaque/high-attenuation focus include dystrophic calcification, displaced bone or root fragments, or a cemental tear.^1-5 Owing to the linear nature of the radiopaque/high-attenuation entities and their positions parallel to the adjacent root surfaces, cemental tears were suspected. There was visual confirmation of sloughing cementum in 1 of the reported cases. <h3>DISCUSSION/CONCLUSIONS</h3> Cemental tears tend to be underreported, and this may be due to diagnostic difficulties. Definitive treatment via complete removal of the torn cemental fragment allows for successful healing and prolonged retention of the tooth. A review of the literature is also provided that summarizes the common radiographic presentations of histologically or visually verified cases of cemental tears.

Effect of Different Heat-treated Nickel-Titanium Files on Vertical Root Fracture Resistance

Effect of Different Heat-treated Nickel-Titanium Files on Vertical Root Fracture Resistance

Vertical root fracture resistance and dentinal crack formation of root canal-treated teeth instrumented with different nickel-titanium rotary systems: an in-vitro study.

To compare the vertical root fracture (VRF) resistance of root canal-treated teeth instrumented with four different nickel-titanium (NiTi) rotary file systems and examine the dentinal crack pattern and direction using a new classification. Eighty mature mandibular premolars were selected and decoronated, leaving 13mm of the root. The root samples were mounted in acrylic resin and divided randomly into five groups of different NiTi file systems: Group 1-control, Group 2-T-Pro, Group 3-HyFlex CM, Group 4-TG6 and lastly Group 5-ZenFlex. Samples in Group 2 and Group 3 were instrumented up to size 25/0.04, whereas Group 4 and Group 5 were instrumented up to size 25/0.06. Obturation was performed with AH Plus sealer and gutta-percha using single cone technique. Subsequently, all samples were subjected to occlusal compressive force until they were fractured. The force (N) needed to cause root fracture was recorded. The crack patterns and directions were also inspected under magnification and classified using a new and simple classification. The highest (VRF) resistance was noted in the control group (453.15 ± 92.23N), followed by T-Pro (387.43 ± 76.81N), HyFlex CM (381.88 ± 52.73N), ZenFlex (369.15 ± 89.41N) and finally TG6 (346.05 ± 72.08N), but there was no significant difference between T-Pro and HyFlex (P = 0.438). A significantly higher prevalence (P = 0.001) of Type 1 crack pattern was observed, especially in samples instrumented with TG6. Majority of the cracks ran buccolingually except in some samples instrumented with ZenFlex (P = 0.898). Smaller file taper increased the VRF resistance of root canal-treated teeth. Majority of the dentinal crack exhibited Type 1 pattern and ran buccolingually.

Influence of metal artefact reduction tool on the detection of vertical root fractures involving teeth with intracanal materials in cone beam computed tomography images: A systematic review and meta-analysis.

The effectiveness of the metal artefact reduction (MAR) tool for the detection of vertical root fracture (VRF) by cone beam computed tomography (CBCT) images is controversial. To evaluate the effectiveness of the MAR tool on VRF detection involving teeth with intracanal materials in CBCT images. In September 2019, an electronic search was performed in six databases (PubMed, Scopus, Web of Science, Cochrane, Lilacs and Embase). The electronic search was updated in May 2020 through searches in Google Scholar and references of included studies (embracing the electronic and gray literature searches). No language or year restrictions were applied. Independently, two reviewers examined titles, abstracts and full texts according to the eligibility criteria that were as follows: diagnostic studies that evaluated the effectiveness of the MAR tool on the diagnosis of VRF in human teeth (laboratory or in vivo studies) on CBCT images. The risk of bias was evaluated using the Quality Assessment Tool for Diagnostic of Accuracy Studies-2 (QUADAS-2). For conducting the meta-analysis, the values of sensitivity, specificity, diagnostic odds ratio (DOR) and area under the ROC curve (AUC) were obtained, considering the subgroups with and without MAR active. The Grading of Recommendation, Assessment, Development and Evaluation instrument was applied to assess the level of evidence across the studies using GRADEpro software. A total of 8 laboratory studies were included in both systematic review and meta-analysis. The values of sensitivity, specificity, DOR and AUC to VRF diagnosis with and without MAR active were, respectively, 0.586 and 0.603; 0.699 and 0.713, 3.037 and 3.767; 0.67 and 0.71. The quality of the evidence suggested low confidence in estimating the outcomes. The MAR tool decreased slightly the diagnostic values of VRF involving teeth with intracanal materials in laboratory studies. However, it is important to highlight that most studies had an uncertain risk of bias. Although a low level of evidence and high heterogeneity were observed in the included studies, the meta-analysis revealed better diagnosis values for VRF detection when the MAR was deactivated when analysing extracted teeth in a laboratory setting. PROSPERO-CRD42020145222. This study was financed in party by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasil (CAPES).

Diagnosis of cracked teeth using cone-beam computed tomography: literature review and clinical experience

Cone-beam computed tomography (CBCT) has been widely used in diagnosis of vertical root fractures (VRFs) in recent years. According to the American Association of Endodontists (AAE) classification, there are five types of cracked teeth and VRF is one of them. Due to the variability and overlapping of the cracks and fractures, some narrow fractures on the roots of VRFs could not be detected by CBCT, and some wide cracks on the crown of cracked teeth could be detected by CBCT. In this review, we firstly discussed the value of CBCT in the diagnosis of the AAE five types of cracked teeth and presented CBCT manifestations of some typical cases. Secondly, we summarized the factors influencing the diagnosis of cracks/fractures using CBCT, namely, CBCT device-related factors, patient-related factors, and evaluator-related factors. The possible strategies to improve the diagnostic accuracy in the clinic practice are also discussed in this part. Finally, we compared the differences of root fractures with lateral canals and external root resorption on CBCT images.

Combined Use of 2 Cone-beam Computed Tomography Scans in the Assessment of Vertical Root Fracture in Teeth with Intracanal Material

IntroductionThe purpose of this preliminary study was to evaluate the diagnostic accuracy of the combined use of 2 cone-beam computed tomographic (CBCT) volumes obtained with the tooth of interest positioned at different orientations in the detection of vertical root fracture (VRF). MethodsThirty single-rooted teeth were divided into 2 main groups (n = 15): control and with VRF. The teeth were individually placed in a phantom composed of a human skull and mandible, which was CBCT scanned in 2 spatial orientations: conventional (with the Frankfurt plane parallel to the floor) and angled acquisition (tilted 90° backward). Also, each tooth was scanned with gutta-percha, a metal post, and without any intracanal material. Three oral radiologists individually evaluated the images resulting from conventional acquisition and verified the presence or absence of VRF (conventional CBCT assessment), setting a score on a 5-point scale. Subsequently, the observers evaluated both images resulting from the conventional and angled acquisitions (combined CBCT assessment). The diagnostic values of the conventional and combined assessments were compared using 2-way analysis of variance with the post hoc Tukey test. The significance level was set at 5% (α = 0.05). ResultsThe combined CBCT assessment showed higher accuracy and sensitivity in the VRF diagnosis of teeth filled with gutta-percha (P < .05). In teeth with a metal post, all diagnostic values were higher in the combined CBCT assessment (P < .05). ConclusionsThis preliminary study suggests that the CBCT-based diagnosis of VRF in teeth with intracanal material was improved when the assessment combines images obtained at 2 orientations.

Performance of Bioceramic-based Root Filling Material with Artifact Reduction Properties in the Detection of Vertical Root Fractures Using Cone-beam Computed Tomography

Introduction: In Cone-beam Computed Tomography (CBCT) images, metallic artifacts by root filling materials reduce the quality of images. It seems that bioceramic sealers produce fewer artifacts than gutta-percha. In this situation, the possibility of VRF detection could increase, and therefore, flap and exploratory surgery would not be needed. The purpose of this study was to evaluate the performance of a bioceramic-based root filling material in the detection of Vertical Root Fractures (VRF) in CBCT imaging. Materials and Methods: This study was conducted at the dental school from March to August 2019, and 100 healthy human mandibular premolar teeth were obtained and randomly divided into two equal groups. The teeth were filled with either AH26 and gutta-percha or bioceramic root filling materials. VRF was induced on half of the decoronated teeth in each group using a Global Testing Machine, and the others were considered control. CBCT imaging was performed by the Cranex 3D machine. Comparisons of the 2 groups were made using the Mann-Whitney test. Results: There was a significant difference between the two groups of bioceramic and gutta-percha in the measured indices, including sensitivity (P=0.017), specificity (P=0.018), positive predictive value (P=0.018), negative predictive value (P=0.018), and accuracy (P=0.011). The Area Under Curve (AUC) also showed a significant difference between the two groups (P=0.011). According to Kappa test results, no significant difference was obtained between the findings of the two observers. Conclusion: Different root filling materials showed a different extent of artifact in CBCT images. Bioceramic root filling material induces fewer artifacts in CBCT images, and the diagnostic value of VRF in CBCT images in the root canals filled with it is greater than those filled with AH26 and gutta-percha.

Three-year clinical performance of posterior monolithic zirconia single crowns

Statement of problemMonolithic zirconia has become widely used for single crowns, with the advantages of minimal tooth reduction and good esthetics. However, clinical studies evaluating the performance of and patient satisfaction with posterior monolithic zirconia crowns are sparse. PurposeThe purpose of this clinical study was to evaluate the clinical performance of and patient satisfaction with posterior monolithic zirconia crowns. Material and methodsWithin a prospective cohort study design, participants were recruited from a university dental clinic if they required 1 posterior monolithic zirconia crown. The clinical performance was evaluated at follow-up appointments 1, 2, and 3 years after insertion. Bleeding on probing and pocket probing depths for the crowned teeth were recorded. Overall patient satisfaction was measured by using a visual analog scale (VAS), and quality of life was measured by using the validated German version of the Oral Health Impact Profile 14 (OHIP-G14). Descriptive statistical methods were applied. Mean values were calculated and compared by using the paired t test (α=.05). ResultsThirty participants received a monolithic zirconia crown (14 premolars, 16 molars). One biologic complication (vertical root fracture) was identified at the 1-year follow-up. Three years after insertion, 22 participants could be examined, and the crowns were still in function. The gingival and the periodontal status of the crowned teeth had not changed significantly over the 3 years. After insertion, a significant improvement in patient satisfaction was measured up to 3 years ConclusionsPosterior monolithic zirconia crowns led to enhanced patient satisfaction up to 3 years after insertion. They provided good middle-term success and offered a promising alternative to conventional metal-ceramic crowns.

“CBCT-THE THIRD AND THE MOST DIAGNOSTIC DIMENSION”: A CASE REPORT

Radiology is an essential tool in the dental clinical practice as most structures harbouring disease are not visible to the naked eye. There are various entities that are generally not noticed until periapical pathology occurs. Under such circumstances, the diagnosis is difcult, as they mimic various other conditions. One of such condition is root fracture after an endodontic treatment of tooth. Vertical root fracture (VRF) usually starts from an internal dentinal crack and develops over time, due to masticatory forces and occlusal loads. Here in this paper we will discuss how we stepwise diagnostic radiographic modalities are used to see the actual cause of pain in a 60 year old male patient. Cone Beam Computed Tomography (CBCT) was done to view in 3D which revealed VRF of tooth. Throughout the paper the edge of CBCT over other diagnostic modalities is discussed till we get our diagnosis.

Influence of retreatment in the formation of dentinal microcracks in mandibular molars filled with a calcium silicate based sealer

Introduction: In endodontically treated teeth, dentinal defects such as microcracks can progress to a vertical root fracture and lead to tooth loss. Objective: The present study aimed to evaluate, by micro-computed tomography analysis, the formation of dentinal microcracks during filling removal in endodontic retreatment of root canals filled with gutta-percha and Total Fill BC bioceramic sealer. Methods: Twenty mesial roots of mandibular molars were instrumented and obturated with gutta-percha and Total Fill BC sealer and then the filling material was removed with rotary Protaper Retreatment files. The specimens were scanned before instrumentation, after filling and after retreatment. The transversal images obtained after filling were compared with the images obtained after removal of the filling material. A descriptive statistical analysis was performed. Results: Among the 24.444 cross-sections analyzed, 5.67% presented some type of dentinal defect, with 0.51% in the initial images, 2.58% in the post-filling images and 2.58% in the post-retreatment images. All the dentinal defects identified in the images obtained after the retreatment were already present in the corresponding images after the filling. New dentinal microcracks were not observed after removal of the filling material. Conclusion: Retreatment of mesial roots of mandibular molars filled with a silicate-based root canal filling material do not influence the formation of dentinal microcracks.

Crack propagation in radicular dentin after the root canal preparation with the different NiTi rotary files an ex vivo study

Cracks that occur during endodontic procedures can propagate by occlusal forces, with repeated stress finally resulting in VRFs. At times, we inevitably end up damaging root dentin which becomes a Gateway for infections like perforation, zipping, dentinal cracks and minute intricate fractures or even vertical root fractures, thereby resulting in failure of treatment. Several factors may be responsible for the formation of dentinal cracks like high concentration of sodium hypochlorite, compaction methods and various canal shaping methods. The prognosis of a tooth with a VRF is poor. The final apical preparation size is an important factor in root canal cleanliness. This article discusses the current concepts in the usage of NiTi rotary files in endodontic therapy and their comparison with hand files in order to draw some clinical inferences.

Influence of Various Irrigation Protocols on Resistance to Vertical Root Fracture in Root Canal Treated Teeth

Introduction: This study compared influence of various irrigation protocols on vertical root fracture resistance of root canal treated teeth. Methods: Forty-eight extracted mandibular premolars were included in the study. The root canals of teeth were instrumented and specimens were allocated into 4 (n = 12) groups according to the irrigation solutions: Group 1: 5% EDTA, 2.5% NaOCl and DW; Group 2: 5% EDTA, 2.5% NaOCl, DW and 2% CHX; Group 3: 5% EDTA, 2.5% NaOCl and 5% Na2S2O3; Group 4: 5% EDTA, 2.5% NaOCl, 5% Na2S2O3 and 2% CHX. Root canals were filled and a load in a vertical direction was applied a week later to specimens. The data were analysed using two-way ANOVA test (P < 0.05). Results: Interaction between using DW or Na2S2O3 and using or not using CHX had a significant effect on fracture resistance to vertical forces (P < 0.001). Irrigation with Na2S2O3 improves fracture resistance to vertical forces when compared to irrigation with DW (P < 0.001). Irrigation with CHX did not affect fracture resistance to vertical forces (P = 0.759). Conclusion: The irrigation solutions statistically affect resistance of root canal treated teeth to vertical fracture forces.

Shrinkage Strains in the Dentin of Endodontically Treated Teeth with Water Loss

IntroductionDehydration has been considered as a potential contributor to vertical root fractures (VRFs) after root canal treatment (RCT). A loss of water could cause embrittlement of dentin and detrimental shrinkage strains. Senior patients have the highest risk of VRF. In this study, we characterized the spatial distribution in shrinkage of tooth roots with respect to donor age and prior RCT. MethodsSingle-rooted human teeth with and without prior RCT were collected from young (age <25 years) and old (age >60 years) adults. Transverse slices were sectioned from the apical, middle, and coronal thirds of the roots, and digital image correlation was used to evaluate shrinkage during free convection. Crack initiation and growth analysis was performed via optical microscopy, and bound water in dentin was characterized by Raman spectroscopy. ResultsThe rate of shrinkage was significantly higher (p ≤ .05) in the apical third than in the middle and coronal thirds of all teeth regardless of donor age. The highest shrinkage strain occurred in the apical third of old donor teeth with prior RCT. In addition, the RCT-treated old teeth suffered the highest percentage of water loss with dehydration. Cracks initiated from the root surface and extended toward the canal with loss of water and shrinkage. ConclusionsThe apical third undergoes significantly larger shrinkage strains with dehydration than the remainder of the root. Prior RCT exacerbates the extent of shrinkage, particularly in the teeth of seniors and after clinical function, which could increase the propensity for VRF.