Load and strain during lateral condensation and vertical root fracture

doi:10.1016/S0099-2399(99)80005-3

Journal of Endodontics

Volume 25, Issue 2, February 1999, Pages 99-104

https://doi.org/10.1016/S0099-2399(99)80005-3 Get rights and content

Vertical loads and root surface strains in extracted teeth during lateral condensation using finger and hand spreaders were measured and compared with loads and strains at fracture. Six groups each of 10 teeth were tested: maxillary central incisor, premolar and molar; and mandibular incisor, premolar and molar. Root strains were measured using strain gauges mounted on the apical and middle third of the buccal root surface. Statistical analysis was performed at the 95% level of confidence. The maximum loads and strains generated by finger spreaders were significantly lower than those generated using a hand spreader (D11T). These loads and strains were also significantly lower than the values at fracture. Most fracture lines were in a buccolingual direction, but maxillary premolars with two separate roots and the mesiobuccal root of maxillary molars showed more variation in fracture site. The results suggest that lateral condensation alone should not be a direct cause of vertical root fracture. The use of finger spreaders, however, is associated with lower risk.

References (20)

PittsDL et al.
Diagnosis and treatment of vertical root fractures
J Endodon
(1983)
SeldenHS
Repair of incomplete vertical root fractures in endodontically treated teeth—in vivo trials
J Endodon
(1996)
GherME et al.
Clinical survey of fractured teeth
J Am Dent Assoc
(1987)
SawL-H et al.
Root strains associated with different obturation techniques
J Endodon
(1995)
HarveyTE et al.
Lateral condensation stress in root canals
J Endodon
(1981)
HolcombJQ et al.
Further investigation of spreader loads required to cause vertical root fracture during lateral condensation
J Endodon
(1987)
PittsDL et al.
An in vitro study of spreader loads required to cause vertical root fracture during lateral condensation
J Endodon
(1983)
LindauerPA et al.
Vertical root fractures in curved roots under simulated clinical conditions
J Endodon
(1989)
DangDA et al.
Vertical root fracture and root distortion: effect of spreader design
J Endodon
(1989)
WaltonRE et al.
The histopathogenesis of vertical root fractures
J Endodon
(1984)

There are more references available in the full text version of this article.

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A narrative review of cracks in teeth: Aetiology, microstructure and diagnostic challenges
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To summarize the available evidence of crack formation in teeth and to discuss the limitations of the current clinical diagnostic modalities for crack detection in teeth.
Cracks are a common clinical finding in teeth and yet clinicians still struggle to identify the full extent and orientation of cracks for their appropriate timely management. The biomechanics of crack development can be due to multiple factors and can differ from an unrestored tooth to a restored or endodontically treated tooth.
This narrative review has been designed following the guidelines published by Green et al. 2006 [1] Published literature in the English language that addresses the objectives of this review up to July 2022 was sourced from online databases and reference lists. The relevance of the papers was assessed and discussed by two reviewers. A total of 101 publications were included in this narrative review.
The initiation and development of cracks in teeth are likely linked to an interplay between the masticatory forces and fracture resistance of the remaining tooth structure. From the identified literature, the quality and quantity of remaining tooth structure in a restored or endodontically-treated tooth affects the biomechanics of crack development compared to an unrestored tooth. The extent, orientation, and size of the cracks do affect a clinician's ability to detect cracks in teeth. There is still a need to develop reliable diagnostic tools that will accurately identify cracks in teeth beneath restorations to enable effective monitoring of their propagation and provide appropriate interventions.
The development and propagation of cracks in an unrestored tooth differ greatly from a restored and endodontically treated tooth; mainly linked to the quantity and quality of the remaining tooth structure and the forces acting on them. Identifying the extent of cracks in teeth remains challenging for early clinical intervention.
Comparison of Dentin Microstructure and Its Correlation to the Direction of Fracture Line in Mandibular Molars of Young and Older Individuals: In Vitro Study
2023, Journal of Endodontics
The aim of the study was to assess the presence and extent of sclerotic dentin and to study its impact on the direction of fracture lines in extracted mandibular first molars of young (20–44 years) and older age groups (45 and older).
Extracted permanent mandibular first molars were collected along with the related demographic details. A total of 40 teeth were included in this study, 20 each from young age group (YA group) (20–44 years) and older age group (OA group) (45–70 years). All molars were decoronated, and the sectioned mesial roots were embedded in acrylic blocks. They were subjected to vertical force in a universal testing machine. Fractured roots were then examined under the stereomicroscope at ×8 magnification to determine the direction and pattern of the fracture line. The roots were then sectioned and evaluated at ×10 and ×20 magnification to assess the dentin microstructure and its correlation with the direction of the fracture line. Statistical analysis was done by using χ² test (P < .05).
A greater incidence and degree of sclerotic dentin were found in the OA group as compared with the YA group, which was statistically significant. The sclerotic dentin was distributed predominantly mesiodistally and the fracture line propagated buccolingually in both young and older groups, which was statistically significant (P < .05).
The presence of sclerotic dentin mesiodistally may impede crack propagation in this direction for both young and older age groups, causing the fracture line to extend buccolingually in coronal third of the root.
Risk Factors for and Clinical Presentations Indicative of Vertical Root Fracture in Endodontically Treated Teeth: A Systematic Review and Meta-analysis
2023, Journal of Endodontics
The aim of this study was to identify specific clinical signs or symptoms and potential risk factors which are most likely associated with the presence of a vertical root fracture (VRF) in endodontically treated teeth (ETT).
Electronic databases (MEDLINE via PubMed, EMBASE via Ovid, Scopus, and Web of Science) were searched by 2 reviewers in October 2022 for clinical studies, in which at least either the clinical presentation or potential risk factors associated with a VRF were assessed. Risk of bias was assessed using the Newcastle-Ottawa scale. Meta-analyses of odds ratios (ORs) were performed separately for several signs or symptoms and risk factors.
Fourteen sources reporting on 2877 teeth (489 with VRF and 2388 without VRF) were included in the meta-analyses. Regarding the clinical presentation, the presence of sinus tracts (OR = 4.87; 95% confidence interval [CI], 1.58–15.0), increased periodontal probing depths (OR = 13.24; 95% CI, 5.44–32.22), swelling/abscess (OR = 2.86; 95% CI, 1.74–4.70), and tenderness to percussion (OR = 1.76; 95% CI, 1.18–2.61) were significantly associated with the presence of a VRF (P_adj. value < .05). None of the assessed risk factors (sex, type of teeth, tooth location, posts, indirect restoration, and apical extension of the root canal filling) were found to be significantly associated with the presence of a VRF (P_adj. value > .05).
Four clinical presentations were identified to be the most significant signs or symptoms for a VRF in ETT: presence of sinus tracts, increased probing depths, swelling/abscess, and tenderness to percussion. None of the assessed risk factors pointed out to be significantly associated with a VRF. Registration: CRD42022354108 (PROSPERO).
Vertical Root Fracture in Buccal Roots of Bifurcated Maxillary Premolars from Condensation of Gutta-percha
2018, Journal of Endodontics
Maxillary premolars are among the teeth most susceptible to vertical root fracture (VRF) from lateral condensation of gutta-percha. These teeth are distinguished by a complex anatomy of the buccal root including a large depression in the dentin wall facing the bifurcation. It is hypothesized that tooth sectioning coupled with 2-dimensional fracture analysis is instrumental in understanding VRF in such teeth. VRF was examined by tooth sectioning following the development of a fracture mechanics analysis to predict VRF in such roots.
The fracture morphology in teeth extracted from patients because of VRFs was examined from a series of horizontal cross sections. 2-dimensional fracture mechanics analysis in conjunction with the finite element technique was developed to evaluate VRF caused by canal pressure (q). As in our previous single-rooted tooth model, the apical obturation force (F) was related to q using a simple formula.
Fracture was mostly limited to the buccal root, exhibiting some competing modes including fracture from the depression peak to the canal surface and the canal surface to the root surface, which may occur either along straight lines or curved trajectories resembling the depression outline. The analysis predicted clinical fractures well, yielding VRF force values in the upper range used by clinicians during lateral condensation of gutta-percha.
The main etiology for VRF is stress concentration resulting from the combined effect of wedgelike canal depression and the flexibility of periodontal ligament tissue joining the root and bone. This drawback can be alleviated by minimizing canal enlargement and apical condensation force during root canal therapy.
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2017, Journal of Endodontics
Citation Excerpt :
Another important factor with respect to the fracture strength of endodontically treated teeth is the stress generated during filling. Stress-distribution studies report stress transmission to dentin during different procedures involving strain gauges (29) or photoelastic materials (30). These studies have shown that the force to fracture a root is much higher than the force that occurs during lateral condensation.
This study evaluated the effects of endodontic treatment and retreatment on the fatigue failure load, numbers of cycles for failure, and survival rates of canine teeth.
Sixty extracted canine teeth, each with a single root canal, were selected and randomly divided into 4 groups (n = 15): untreated, teeth without endodontic intervention; prepared, teeth subjected only to rotary instrumentation; filled, teeth receiving complete endodontic treatment; and retreated, teeth retreated endodontically. After the different endodontic interventions, the specimens were subjected to fatigue testing by the stepwise method: 200 N (× 5000 load pulses), 300 N, 400 N, 500 N, 600 N, 800 N, and 900 N at a maximum of 30,000 load pulses each or the occurrence of fracture. Data from load to failure and numbers of cycles for fracture were recorded and subjected to Kaplan-Meier and Log Rank tests (P < .05), in addition to Weibull analysis. The fractures of the specimens were classified as repairable or catastrophic.
The retreated, filled, and untreated groups presented statistically significantly higher fatigue failure loads and numbers of cycles for failure than did the prepared group. Weibull analysis showed no statistically significant difference among the treatments for characteristic load to failure and characteristic number of cycles for failure, although, for number of cycles, a higher Weibull modulus was observed in filled and retreated conditions. The predominant mode of failure was catastrophic.
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^*: This study was supported by a grant from the National Health and Medical Research Council of Australia.

¹: Dr. Lertchirakarn is a postgraduate student, School of Dental Science, University of Melbourne, Victoria, Australia.

²: Dr. Palamara is a research fellow, School of Dental Science, University of Melbourne, Victoria, Australia.

³: Dr. Messer is professor of Restorative Dentistry. School of Dental Science, University of Melbourne, Victoria, Australia.

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Journal of Endodontics

References (20)

Diagnosis and treatment of vertical root fractures

J Endodon

Repair of incomplete vertical root fractures in endodontically treated teeth—in vivo trials

J Endodon

Clinical survey of fractured teeth

J Am Dent Assoc

Root strains associated with different obturation techniques

J Endodon

Lateral condensation stress in root canals

J Endodon

Further investigation of spreader loads required to cause vertical root fracture during lateral condensation

J Endodon

An in vitro study of spreader loads required to cause vertical root fracture during lateral condensation

J Endodon

Vertical root fractures in curved roots under simulated clinical conditions

J Endodon

Vertical root fracture and root distortion: effect of spreader design

J Endodon

The histopathogenesis of vertical root fractures

J Endodon

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Risk Factors for and Clinical Presentations Indicative of Vertical Root Fracture in Endodontically Treated Teeth: A Systematic Review and Meta-analysis

Vertical Root Fracture in Buccal Roots of Bifurcated Maxillary Premolars from Condensation of Gutta-percha

Influence of Endodontic Treatment and Retreatment on the Fatigue Failure Load, Numbers of Cycles for Failure, and Survival Rates of Human Canine Teeth

Assessment of the Penetration of an Endodontic Sealer into Dentinal Tubules with Three Different Compaction Techniques Using Confocal Laser Scanning Microscopy

Load and strain during lateral condensation and vertical root fracture*

J Endodon

J Endodon

J Am Dent Assoc

J Endodon

J Endodon

J Endodon

J Endodon

J Endodon

J Endodon

J Endodon