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BioMed Research International 2019The aim of this study was to evaluate the influence of ferule and the post type on the fracture strength and stress distribution in premolars.
OBJECTIVES
The aim of this study was to evaluate the influence of ferule and the post type on the fracture strength and stress distribution in premolars.
MATERIALS AND METHODS
Forty human mandibular premolars were decoronated, allocated in four groups, and restored as follows: CPC-NF: cast post-and-core and absence of ferule; CPC-F: cast post-and-core and presence of ferule; FPC-NF: glass-fiber posts and absence of ferule; FPC-F: glass-fiber posts and presence of ferule. The fracture strength (FS) and failure patterns were evaluated. Finite element analysis (FEA) evaluated the stress distribution.
RESULTS
FS did not differ between CPCs and FPC either in presence or in absence of ferule. The presence of ferule increased FS with both post types. Mean values of FS for ferule groups were higher than functional or parafunctional loads reported in literature, which was not the case for FPC-NF when compared to parafunctional loads. FEA with a functional load showed slightly higher compressive stresses in dentin in the group CPC-NF, which was much lower than the compressive strength of dentin. Lower percentage of catastrophic failures was observed in nonferule groups irrespective of post type, which was explained by the stress concentration in the cervical root region when FEA with the FS load was simulated.
CONCLUSION
Ferule effect was shown to be more important than post type in the analysis. Both posts showed potential to withstand functional loads irrespective of presence of ferule. However, the mean FS was lower than parafunctional loads for FPC in the absence of ferule.
Topics: Bicuspid; Composite Resins; Compressive Strength; Dental Materials; Dental Restoration Failure; Dental Stress Analysis; Finite Element Analysis; Flexural Strength; Glass; Humans; Materials Testing; Resin Cements; Stress, Mechanical; Tooth Fractures
PubMed: 30719440
DOI: 10.1155/2019/2196519 -
Medicina (Kaunas, Lithuania) Oct 2022: The purpose of this study is to observe the usefulness of autogenous tooth transplantation by examining the cumulative survival rate according to the period of...
: The purpose of this study is to observe the usefulness of autogenous tooth transplantation by examining the cumulative survival rate according to the period of auto-transplanted teeth as pre-implant treatment. : This study was conducted on 111 patients who visited Kyungpook National University Dental Hospital and underwent autogenous tooth transplantation between November 2008 and January 2021 (about 13 years). The cumulative survival rate of autogenous tooth transplantation according to the causes of extraction of the recipient tooth (caries, periapical lesion, crack, crown fracture, periodontitis) and condition of opposing teeth (natural teeth vs. fixed prosthesis). The cumulative survival rate of autogenous tooth transplantation according to the age (under 30 vs. over 30) was also investigated and it was examined whether there were any differences in each factor. : The average follow-up period was 12 months, followed by a maximum of 162 months. The 24-month cumulative survival rate of all auto-transplanted teeth was 91.7%, 83.1% at 60 months and the 162-month cumulative survival rate was 30.1%. There were no statistical differences between the causes of extraction of the recipient's teeth, differences in the condition of the opposing teeth, and differences under and over the age of 30. : The survival rate of autogenous tooth transplantation appears to be influenced by the conditions of the donor tooth rather than the conditions of the recipient tooth. Although autogenous tooth transplantation cannot completely replace implant treatment, it is meaningful in that it can slightly delay or at least earn the time until implant placement is possible.
Topics: Humans; Survival Rate; Tooth; Transplantation, Autologous; Tooth Extraction; Tooth Fractures; Follow-Up Studies; Treatment Outcome
PubMed: 36363473
DOI: 10.3390/medicina58111517 -
Acta Biomaterialia Mar 2015A model for the splitting of teeth from wedge loading of molar cusps from a round indenting object is presented. The model is developed in two parts: first, a simple 2D...
A model for the splitting of teeth from wedge loading of molar cusps from a round indenting object is presented. The model is developed in two parts: first, a simple 2D fracture mechanics configuration with the wedged tooth simulated by a compact tension specimen; second, a full 3D numerical analysis using extended finite element modeling (XFEM) with an embedded crack. The result is an explicit equation for splitting load in terms of indenter radius and key tooth dimensions. Fracture experiments on extracted human molars loaded axially with metal spheres are used to quantify the splitting forces and thence to validate the model. The XFEM calculations enable the complex crack propagation, initially in the enamel coat and subsequently in the interior dentin, to be followed incrementally with increasing load. The fracture evolution is shown to be stable prior to failure, so that dentin toughness, not strength, is the controlling material parameter. Critical conditions under which tooth splitting in biological and dental settings are likely to be met, however rare, are considered.
Topics: Adult; Biomechanical Phenomena; Dental Stress Analysis; Finite Element Analysis; Humans; Models, Theoretical; Molar; Tooth Fractures; Young Adult
PubMed: 25584989
DOI: 10.1016/j.actbio.2015.01.004 -
The Bulletin of Tokyo Dental College 2017The goal of this study was to investigate length of time between full pulpotomy and a definitive diagnosis of vertical root fracture (VRF), as well as the age at which...
The goal of this study was to investigate length of time between full pulpotomy and a definitive diagnosis of vertical root fracture (VRF), as well as the age at which this was made. The participants comprised 63 dental patients (40 men and 23 women) with a mean age of 65.7±10.4 years in whom a definitive diagnosis of VRF had been made between July 2013 and June 2015, and who had also undergone a full pulpotomy. The data on all these cases were obtained from 22 dental clinics belonging to a clinical study group. The mean duration between a full pulpotomy and a definitive diagnosis of VRF was 141.0±88.9 months. The results showed no differences in terms of sex, mandible/maxilla, or tooth type. No relationship was observed between age at which the diagnosis was made and length of time between full pulpotomy and diagnosis (Pearson correlation coefficient = 0.162) (p>0.05). Most diagnoses of VRF were made in patients aged over 50 years, irrespective of length of time between full pulpotomy and the diagnosis. These results suggest that age is a stronger indicator of VRF than length of time between full pulpotomy and a definitive diagnosis.
Topics: Aged; Female; Humans; Male; Middle Aged; Pulpotomy; Root Canal Therapy; Time Factors; Tooth Fractures; Tooth Root
PubMed: 28381736
DOI: 10.2209/tdcpublication.2016-0016 -
Brazilian Dental Journal 2021The objective of this critical review of literature is to discuss relevant clinical factors associated with root fractures (RF) visualized by using a new CBCT software.... (Review)
Review
The objective of this critical review of literature is to discuss relevant clinical factors associated with root fractures (RF) visualized by using a new CBCT software. RF constitutes a common occurrence and a challenge in clinical practice, in which the diagnosis becomes essential for the definition of rapid and precise decision-making. The characterization of RF may involve different aspects, such as orientation of the fracture line (horizontal, vertical, oblique), root position of the fracture (cervical, middle, apical third), fracture's coronal-radicular position (coronary, coronal-radicular, radicular), continuity of the fracture (crack, incomplete fracture, complete), bone extension of the fracture (supraosseous, bone level, infraosseous fracture). Imaging examinations have been routinely used to aid in the RF diagnosis. Even with high-resolution cone-beam computed tomography (CBCT) scans, many doubts often remain about the diagnostic outcome. Many interferences in the analysis of image quality to determine the diagnosis are identified, such as the sharpness, the noise, light and dark artifacts, among others. The professional's knowledge is essential for identifying the different patterns of fracture lines and their repercussions on adjacent bone tissues, as well as for the analysis of artifacts that may hide or show similarities to fracture lines. Fractures lines and root fractures that may be associated with phantom conditions that mimic fractures should be carefully analyzed. CBCT is the exam indicated to identify a root fracture. It is also added to the success of the diagnosis that the professional has scientific knowledge, training and mastery of advanced CBCT software.
Topics: Cone-Beam Computed Tomography; Diagnosis, Differential; Humans; Spiral Cone-Beam Computed Tomography; Tooth Fractures; Tooth Root
PubMed: 34877973
DOI: 10.1590/0103-6440202104742 -
BMC Oral Health Dec 2022The purpose of this study was to investigate the fracture strength and stress distribution of four ceramic restorations.
BACKGROUND
The purpose of this study was to investigate the fracture strength and stress distribution of four ceramic restorations.
METHODS
Forty human mandibular first molars were collected and randomized into four groups after establishing the distal defect: full crown group with 4 mm axial wall height (AWH) (FC4); short AWH crown group with 2 mm AWH (SC2); occlusal veneer group with 0 mm AWH (OV0); occlusal distal veneer group with only the distal surface prepared, and 4 mm AWH (OD4). The teeth were prepared according to the groups and the ceramic restorations were completed using celtra duo ceramic blocks. The ceramic thickness of the occlusal surface is about 1.5 mm and the edge is about 1 mm. The failure load values and fracture modes of each group were detected by mechanical test in vitro. According to the groups to establish three-dimensional finite element analysis (FEA) models, a 600 N loading force was applied vertically using a hemispherical indenter with a diameter of 6 mm. and compare the stress distribution under the condition of different restorations.
RESULTS
In vitro mechanical tests showed that the failure load values were SC2 (3232.80 ± 708.12 N) > OD4 (2886.90 ± 338.72 N) > VO0 (2133.20 ± 376.15 N) > FC4(1635.40 ± 413.05 N). The failure load values of the short AWH crown and occlusal distal veneer were significantly higher than that of occlusal veneer and full crown (P<0.05). The fracture modes of the full crown and occlusal veneer groups were mainly ceramic fractures and some were restorable tooth fractures. The short AWH crown and occlusal distal veneer groups presented with three fracture modes, the proportion of non-restorable tooth fracture was higher. The results of FEA show that under the spherical loading condition, the stress of ceramic was concentrated in the contact area of the loading head, the maximum von Mises stress values were FC4 (356.2 MPa) > VO0 (214.3 MPa) > OD4 (197.9 MPa) > SC2 (163.1 MPa). The stress of enamel was concentrated in the area where the remaining enamel was thinner, the maximum von Mises stress values was OD4 (246.2 MPa) ≈ FC4 (212.4 MPa) > VO0 (61.8 MPa) ≈ SC2 (45.81 MPa). The stress of dentin is concentrated in the root furcation and the upper third region of the root. However, stress concentration was observed at the tooth cervix in the full crown.
CONCLUSION
Under certain conditions, the occlusal distal veneer shows better performance than the full crown.
Topics: Female; Humans; Flexural Strength; Molar; Ceramics; Dental Enamel; Tooth Fractures
PubMed: 36456942
DOI: 10.1186/s12903-022-02577-5 -
Scanning 2022Using a modified thermal cycling method to establish narrow root fracture models and evaluate the diagnosis efficiency of them using four different cone-beam CT (CBCT)...
AIM
Using a modified thermal cycling method to establish narrow root fracture models and evaluate the diagnosis efficiency of them using four different cone-beam CT (CBCT) units. . Fifty-six intact teeth were selected, and the crowns of the teeth were embedded using general purpose acrylic resin. 50 root fracture models were established by soaking these teeth in liquid nitrogen and hot water cyclically; 6 teeth were used as the negative control. All the 56 teeth were scanned with the smallest voxel size of four different CBCT units (NewTom VGi, Planmeca Promax 3D Max, Kavo 3D eXam, and Soredex Scanora3D). 10 teeth were randomly selected, and the roots were sliced using slow-speed saw to obtain horizontal root sections. Scanning electron microscope (SEM) was used to measure the width of the fracture lines (FLs). The CBCT images were evaluated for the presence or absence of fracture lines. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the diagnosis of FLs using the four CBCT units.
RESULTS
Fifty narrow root fracture models were successfully established, and 25 root sections with 45 FLs were acquired. The width of FLs was from 3.43 m to 143 m; 32.2% of the points had width under 25 m, while only 9.6% of them had width over 75 m. The accuracy was 0.41, 0.54, 0.41, and 0.30 for NewTom VGi, Planmeca Promax 3D Max, Kavo 3D eXam, and Soredex Scanora3D, respectively.
CONCLUSIONS
The modified temperature cycling method is a simple and effective method to establish narrow root fracture models, and the diagnosis efficiency for these narrow fracture lines was quite poor using all the four different CBCT units.
Topics: Cone-Beam Computed Tomography; Humans; Temperature; Tooth; Tooth Fractures; Tooth Root
PubMed: 35912120
DOI: 10.1155/2022/3636795 -
Indian Journal of Dental Research :... 2020The history of dentistry is not short; it started from ancient Egypt to ancient Romans and ancient Greeks. When it comes to extraction, all of them have made their own...
PURPOSE
The history of dentistry is not short; it started from ancient Egypt to ancient Romans and ancient Greeks. When it comes to extraction, all of them have made their own discoveries and progress. The progress they made also helped dentistry to move ahead in evolution of new extraction technique - the Physics Forceps. We have assessed the viability in using the Physics Forceps for routine dental extraction in our study for a period of 1 year.
MATERIALS AND METHODS
The study was conducted on 241 patients indicated for extraction based on our inclusion criteria using Physics Forceps after obtaining informed consent and University Ethics Committee approval. Tooth fracture, buccal alveolar bone fracture, and soft tissue injury around the tooth to be extracted were studied.
RESULTS
In our present study of 241 patients, 57.67% were females and 42.32% were males, out of which 93.77% had no tooth fracture, 3.32% had crown fracture, 1.65% had root fracture, and 1.24% had apex fracture. Further, 85.47% had no buccal alveolar bone fracture and 14.53% had buccal alveolar bone fracture. Using proper technique, 96.26% of patients had no soft tissue damage, and minimal damage was seen in 3.73% of patients.
DISCUSSION
Extraction by Physics Forceps is a very good technique of extraction. No or very minimal tooth fracture and soft tissue injury were noted. Though the forceps is costly, it represents a valuable addition to regular armamentarium for a general dentist for routine extraction. Physics Forceps is a dental extractor rather than a forceps.
Topics: Animals; Beak; Female; Humans; Male; Physics; Surgical Instruments; Tooth Extraction; Tooth Fractures; Tooth Socket
PubMed: 32246674
DOI: 10.4103/ijdr.IJDR_433_18 -
The Chinese Journal of Dental Research Sep 2022To undertake a joint analysis of the influence of fracture width, dental thickness and distance of the fracture from the cortical bone on the radiographic diagnosis of...
OBJECTIVE
To undertake a joint analysis of the influence of fracture width, dental thickness and distance of the fracture from the cortical bone on the radiographic diagnosis of vertical root fractures.
METHODS
Thirty-six uniradicular bovine teeth were endodontically treated and distributed into three groups according to the remaining root dentine thickness: 1.2 mm, 1.5 mm and 1.8 mm. Each group comprised 12 teeth, six with vertical root fracture and six without. Scanning electron microscopy (SEM) images of the fractured tooth groups were obtained and the fracture lines were measured. All specimens were inserted into bone defects created in bovine ribs, at different distances from the external cortical bone. Digital periapical radiographs were randomly evaluated by three blinded examiners (presence or absence of fractures).
RESULTS
The specificity for periapical radiography was found to be 89% and the accuracy rate was 57.4%. The mixed-model regression using the generalised estimating equation (GEE) model showed that the width of the fracture line and the thickness of the dental remnant play an important role in radiographic detection of vertical root fractures. There is a lower chance of correct diagnosis with fracture line widths < 0.2 mm (odds ratio [OR] 0.294, 95% confidence interval [CI] 0.103 to 0.836; P = 0.022) and tooth thicknesses < 1.2 mm (OR 0.342, 95% CI 0.157 to 0.747; P = 0.007).
CONCLUSION
Fracture line widths < 0.2 mm and smaller root thicknesses lead to a less accurate diagnosis of vertical root fractures on periapical radiographs.
Topics: Animals; Cattle; Fractures, Bone; Radiography; Tooth Fractures; Tooth Root
PubMed: 36102889
DOI: 10.3290/j.cjdr.b3317977 -
Dental Materials : Official Publication... Jan 2022To investigate the fatigue behavior of restored teeth, in particular the mechanisms of longitudinal dentinal cracking under cyclic mechanical loading, using finite...
OBJECTIVE
To investigate the fatigue behavior of restored teeth, in particular the mechanisms of longitudinal dentinal cracking under cyclic mechanical loading, using finite element analysis (FEA) and the stress-life (S-N) approach.
METHODS
Ten root-filled premolars restored with resin composites were subjected to step-stress cyclic loading to produce longitudinal cracks. Fracture loads and number of cycles completed at each load level were recorded. FEA was used to predict the stress amplitude of each component under the global cyclic load. Both intact and debonded conditions were considered for the dentin-composite interface in the FEA. The predicted stress concentrations were compared with the fracture patterns to help elucidate the failure mechanisms. The S-N approach was further used to predict the lifetimes of the different components in the restored teeth. Cumulative fatigue damage was represented by the sum of the fractions of life spent under the different stress amplitudes.
RESULTS
Longitudinal cracks were seen in ~50% of the samples with a mean fracture load of 770 ± 45 N and a mean number of cycles to failure of 32,297 ± 12,624. The longitudinal dentinal cracks seemed to start near the line angle of the cavity, and propagated longitudinally towards the root. The sum of fractions of life spent for the dentin-composite interface exceeded 1 after ~7000 cycles when that for dentin was much lower than 1, indicating that interfacial debonding would occur prior to dentin fracture. This was supported by micro-CT images showing widened interfacial space in the cracked samples. In the debonded tooth, FEA showed dentinal stress concentrations at the gingival wall of the cavity, which coincided with the longitudinal cracks found in the cyclic loading test. The sum of fractions of life spent for dentin was close to 1 at ~30,000 cycles, similar to the experimental value.
SIGNIFICANCE
Debonding of the dentin-composite interface may occur prior to longitudinal cracking of dentin in root-filled teeth under cyclic loading. The approximate time of occurrence for these events could be estimated using fatigue analysis with stresses provided by FEA. This methodology can therefore be used to evaluate the longevity of restoration designs for root-filled teeth.
Topics: Bicuspid; Composite Resins; Dental Restoration, Permanent; Dental Stress Analysis; Humans; Stress, Mechanical; Tooth Fractures
PubMed: 34949478
DOI: 10.1016/j.dental.2021.12.005