-
Journal of Endodontics Sep 2021This study investigated the impact of different canal tapers and access cavity designs on the life span of endodontically treated mandibular first molars using the...
INTRODUCTION
This study investigated the impact of different canal tapers and access cavity designs on the life span of endodontically treated mandibular first molars using the finite element method.
METHODS
Finite element analysis was performed on simulated models with 3 access cavity designs (traditional, conservative, and truss). The mesial canals were prepared to either constant tapers of 25/.04 and 25/.06 or a variable taper corresponding to the cumulative canal preparation shapes of TruNatomy Prime (Dentsply Sirona, Charlotte, NC) and ProTaper Gold F2 (Dentsply Sirona). The distal canals in all models had a 40/.04 preparation. Using occlusal fingerprint analysis, all models were subjected to cyclic occlusal loading until model failure. The number of cycles until failure, the location of failure, stress distribution patterns, and the maximum von Mises stresses were assessed.
RESULTS
The traditional access models showed a lower life span than the conservative and truss models regardless of the canal taper, whereas there was not a notable difference in the conservative and truss models. The stresses migrated apically along the root surface and remarkably on the mesial aspect of the mesial root and the furcation area's outer surface. After root canal preparation with different tapers, there were no evident changes in the pattern and magnitude of the stresses distributed along the root surface.
CONCLUSIONS
The life span of the tooth is affected more significantly by the access cavity design than the root canal preparation taper. Because stress patterns migrate apically rather than concentrate in the pericervical area, crack initiation and propagation might occur anywhere on the root surface.
Topics: Dental Pulp Cavity; Finite Element Analysis; Longevity; Molar; Root Canal Preparation
PubMed: 34139264
DOI: 10.1016/j.joen.2021.06.009 -
Journal of Oral Science Oct 2021To evaluate the influence of the restorative material and matrix system on proximal contact tightness and morphological characteristics of class II restorations in...
PURPOSE
To evaluate the influence of the restorative material and matrix system on proximal contact tightness and morphological characteristics of class II restorations in primary molars.
METHODS
Occluso-mesial cavities in second primary artificial molars were randomly restored using different materials (Filtek Z500 or Filtek Bulk Fill composites or high-viscosity glass ionomer cement Ketac Universal) and different matrix system (Tofflemire, AutoMatrix, matrix band with ring, contoured sectional matrix) (n = 12). Proximal contact tightness was measured using a custom-made device in an Instron 3345, and proximal surface morphology and marginal adaptation were scored after digital scanning. Two-way ANOVA, Tukey and Fischer's exact tests were performed (P < 0.05).
RESULTS
Proximal contact tightness values were significantly influenced by the restorative material (P < 0.05), the matrix system (P < 0.001), and their interaction (P < 0.01). Both resin composites showed statistically differences in proximal shape according to the matrix used to restore and exhibited overhanging margins. Ketac Universal restorations showed similar morphology and gaps on the margins regardless of the matrix system.
CONCLUSIONS
Overall, both composite restorations achieved tighter proximal contact than those restored with the high-viscosity glass ionomer cement. None of the matrix systems tested provided a convex seamless proximal morphology.
Topics: Dental Materials; Glass Ionomer Cements; Molar; Tooth, Deciduous; Viscosity
PubMed: 34511588
DOI: 10.2334/josnusd.21-0264 -
International Journal of Clinical... Sep 2023To evaluate the thickness of the root canal dentin wall in the cervical, middle, and apical third of primary first molars.
AIM
To evaluate the thickness of the root canal dentin wall in the cervical, middle, and apical third of primary first molars.
MATERIALS AND METHODS
Cross-sectional study consisting of 30 cone-beam computed tomography (CBCT) images of primary maxillary and mandibular first molars, with crown, and root integrity. The wall dentin thickness of each canal was measured in three axial views, divided into distal (D), mesial, lingual/palatine, and buccal surfaces.
RESULTS
The smallest dentin wall thickness of the maxillary molar was located on the mesial surface of the mesiobuccal (MB) canal apical third (mean 0.55 ± 0.04 mm). The buccal and palatal (P) surfaces of the distobuccal (DB) and P canals showed the smallest dentin thickness on the cervical third (0.62 ± 0.02 mm). On the mandibular molar, we found the smallest dentin thickness on the apical third [lingual surface of the MB canal and buccal surface of the mesiolingual (ML) canal] with a mean of 0.41 ± 0.07 mm. Additionally, the dentin thickness is average of the D canal was about 0.67 ± 0.11 mm.
CONCLUSION
It is essential to understand the primary first molar's anatomy to reduce possible complications in pediatric patients from instrumentation during root canal treatments.
CLINICAL SIGNIFICANCE
Pulpectomy is among the most challenging procedures in pediatric dentistry and the knowledge of the root anatomy of primary teeth allows the professional to make better clinical decisions and reduce possible risks during root canal treatment.
HOW TO CITE THIS ARTICLE
Justiniano-Navarro C, Caballero-García S, López-Rodriguez G, Evaluating the Thickness of the Root Canal Dentin Wall in Primary First Molars using Cone-beam Computed Tomography. Int J Clin Pediatr Dent 2023;16(S-2):S122-S127.
PubMed: 38078037
DOI: 10.5005/jp-journals-10005-2660 -
The Journal of Prosthetic Dentistry Apr 2022Systematic reviews about the internal and marginal misfits of fixed prostheses have identified a limited number of clinical studies, suggesting the need for further...
STATEMENT OF PROBLEM
Systematic reviews about the internal and marginal misfits of fixed prostheses have identified a limited number of clinical studies, suggesting the need for further research on the subject. Although the replica technique has been described as suitable for this purpose, few studies have validated it.
PURPOSE
The purpose of this in vitro study was to compare the ability of a nondestructive replica technique and a destructive cementation technique to assess internal and marginal misfits of zirconia copings, considering current materials and designs.
MATERIAL AND METHODS
Twelve anatomic prefabricated abutments (Neodent) were used to manufacture zirconia copings following the Ceramill (Amann Girrbach AG) (n=6) and Lava (3M ESPE) (n=6) systems. Replications of the cementation line were obtained with polyvinyl siloxane for the replica technique, and the copings were then cemented and sectioned to obtain 5 surfaces (buccal, palatal, mesial, distal, and incisal) and the linear and angle regions (internal axiogingival and axioincisal angles). The thickness of the cement line and silicone film was measured at 45 reference points on each abutment. A total of 540 measurements were made with an optical microscope with a digital camera at magnifications of ×100 and ×200. Data were analyzed by repeated-measures ANOVA and the Bonferroni multiple comparison tests (α=.05).
RESULTS
In the internal misfit evaluation, the mean values observed for the cementation technique and replica technique were as follows: angle regions, 70.6 μm and 72.2 μm; linear regions, 59.1 μm and 59.6 μm; incisal surface, 139.0 μm and 139.8 μm; buccal surface, 72.4 μm and 73.8 μm; palatal surface, 73.1 μm and 75.2 μm; mesial surface, 74.1 μm and 73.8 μm; distal surface, 75.0 μm and 76.3 μm; and overall mean, 73.6 μm and 74.8 μm, respectively. In the evaluation of the marginal misfit, the mean values found were: buccal surface, 36.7 μm and 37.8 μm; palatal surface, 37.5 μm and 36.8 μm; mesial surface, 44.0 μm and 43.7 μm; and distal surface, 44.6 μm and 45.2 μm, respectively. No significant differences were found between the 2 techniques for all locations and systems (P>.05).
CONCLUSIONS
Within the limitations of this in vitro study, both techniques presented the same ability to assess the internal and marginal misfits when the location and overall mean averages were evaluated (P>.05).
Topics: Cementation; Computer-Aided Design; Crowns; Dental Marginal Adaptation; Dental Prosthesis Design
PubMed: 33342611
DOI: 10.1016/j.prosdent.2020.11.004 -
Zhonghua Yi Xue Za Zhi Oct 2021To compare the hippocampal volume and local surface morphology changes in patients with mesial temporal lobe (mTLE) using the voxel-based morphometry and spherical...
[The analysis of structural magnetic resonance imaging manifestation of hippocampus based on voxel and spherical harmonic surface morphometry in mesial temporal lobe epilepsy].
To compare the hippocampal volume and local surface morphology changes in patients with mesial temporal lobe (mTLE) using the voxel-based morphometry and spherical harmonic methods respectively. A total of 66 patients (31 males and 35 females, age range from 17 to 48 (28±8) years) with mTLE and 80 age-and gender-matched controls (38 males and 42 females, age range from 19 to 46 (27±7) years) were retrospectively collected from July 2009 to February 2019 at Jinling hospital.. High resolution structural MRI of the whole brain, three-dimensional T-weighted data(3DT1) were acquired from each subject. The changes of hippocampal volume and surface morphology were evaluated between mTLE groups and controls for observing the hippocampal atrophy pattern by using voxel-based morphometry and spherical harmonic shape descriptions point distribution model respectively. Pearson correlation analysis was conducted for observing the relationship between the morphological changes of hippocampus and disease duration. Compared with the controls, hippocampal volume on the affected side in patients with mTLE was significantly reduced (-score:-1.55±0.57 vs 0.38±0.58, <0.001) and negatively correlated with disease duration (=-0.297, =0.016). Furthermore, surface morphology analysis subtly showed that the atrophy of the affected hippocampus in patients with mTLE mainly located in the head, mesial lateral part and posterior tail of the hippocampus. Their displacement values were negatively correlated with disease duration (=-0.336, =0.006) and positively associated with the hippocampal grey matter volume (=0.336, =0.006). Voxel-based morphometry analysis reveals a global reduction in hippocampal volume, while the morphological measurement method based on surface shape can describe the local morphological changes of hippocampal atrophy.
Topics: Adolescent; Adult; Epilepsy, Temporal Lobe; Female; Hippocampus; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Retrospective Studies; Temporal Lobe; Young Adult
PubMed: 34638195
DOI: 10.3760/cma.j.cn112137-20210203-00337 -
NeuroImage. Clinical 2016Despite the common assumption that genetic generalized epilepsies are characterized by a macroscopically normal brain on magnetic resonance imaging, subtle structural...
Despite the common assumption that genetic generalized epilepsies are characterized by a macroscopically normal brain on magnetic resonance imaging, subtle structural brain alterations have been detected by advanced neuroimaging techniques in Childhood Absence Epilepsy syndrome. We applied quantitative structural MRI analysis to a group of adolescents and adults with Juvenile Absence Epilepsy (JAE) in order to investigate micro-structural brain changes using different brain measures. We examined grey matter volumes, cortical thickness, surface areas, and subcortical volumes in 24 patients with JAE compared to 24 healthy controls; whole-brain voxel-based morphometry (VBM) and Freesurfer analyses were used. When compared to healthy controls, patients revealed both grey matter volume and surface area reduction in bilateral frontal regions, anterior cingulate, and right mesial-temporal lobe. Correlation analysis with disease duration showed that longer disease was correlated with reduced surface area in right pre- and post-central gyrus. A possible effect of valproate treatment on brain structures was excluded. Our results indicate that subtle structural brain changes are detectable in JAE and are mainly located in anterior nodes of regions known to be crucial for awareness, attention and memory.
Topics: Adolescent; Adult; Analysis of Variance; Anticonvulsants; Brain; Brain Mapping; Epilepsy, Absence; Female; Functional Laterality; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Middle Aged; Valproic Acid; Young Adult
PubMed: 27551668
DOI: 10.1016/j.nicl.2016.07.007 -
Medicina Oral, Patologia Oral Y Cirugia... Jul 2022A study is made of the findings of high-magnification rigid endoscopy at the root end surface following apicoectomy of teeth subjected to periapical surgery.
BACKGROUND
A study is made of the findings of high-magnification rigid endoscopy at the root end surface following apicoectomy of teeth subjected to periapical surgery.
MATERIAL AND METHODS
A cross-sectional study was made of patients subjected to periapical surgery at the Unit of Oral Surgery and Implantology (University of Valencia, Valencia, Spain) between 2011 and 2019. Following apicoectomy, the root end surfaces were inspected, with the evaluation of untreated canals, isthmuses, craze lines, crack lines, opaque dentin and gaps. Likewise, an analysis was made of the association between patient age and the tooth type and restoration and the presence of craze lines, cracks, opaque dentin and gaps.
RESULTS
The final sample consisted of 168 patients subjected to periapical surgery, with 177 operated teeth and 206 roots. Untreated canals were observed in 14 roots (6.8%). Isthmuses were identified in 74 roots (35.9%), particularly in the mesial root of the lower first molar (94.1%). In turn, craze lines were identified in 8.3% of the roots, cracks in 3.9%, and gaps in 53.4%. The prevalence of opaque dentin was 78.3%, with a greater presence in posterior teeth (90.3% in premolars and 86.2% in molars) than in anterior teeth (50.6%) (p<0.001). Patient age and tooth restoration showed no correlation to the studied parameters.
CONCLUSIONS
Craze lines and crack lines were observed in less than 10% of the roots, though opaque dentin was identified in 73% of the roots, particularly in posterior teeth, and gaps were found in over half of the canals.
Topics: Apicoectomy; Cross-Sectional Studies; Dental Pulp Cavity; Humans; Molar; Tooth Root
PubMed: 35660728
DOI: 10.4317/medoral.25311 -
European Archives of Paediatric... Dec 2021Using software for assessment of restorative work on typodonts in the simulation laboratory may enhance the objective evaluation of student work. The study aimed to...
PURPOSE
Using software for assessment of restorative work on typodonts in the simulation laboratory may enhance the objective evaluation of student work. The study aimed to evaluate the inter-rater and intra-rater reliability using 3-D scans from the Planmeca Emerald™ intra-oral scanner with Romexis Compare software for assessing preparations for preformed metal crowns (PMCs).
METHODS
Three operators independently recorded 3-D scans and digitally measured the features of 30 PMC preparations on typodont primary teeth (# 75). Using Romexis Compare software, preparations were measured from mesial, distal and occlusal aspects. Measurements were repeated after 2 weeks. The intraclass correlation coefficient (ICC) was used to measure the reliability of measurements between operators and within the one operator.
RESULTS
For measuring the extent of tooth reduction, there was excellent intra-rater reliability for each operator (ICC 0.96-0.99). The highest inter-rater reliability was for measurements of the occlusal surface (0.946 and 0.956), followed by the mesial surface (0.852 and 0.862) and then the distal surface (0.746 and 0.724).
CONCLUSION
This method was useful and reliable for measuring features of PMC preparation, but with some limitations. Improving the software to provide specific assistance tools would empower greater uptake of this method as an adjunct to traditional visual grading tool in paediatric dentistry preclinical teaching.
Topics: Child; Crowns; Humans; Laboratories; Reproducibility of Results; Software; Tooth Preparation, Prosthodontic
PubMed: 34059993
DOI: 10.1007/s40368-021-00634-1 -
Microscopy Research and Technique May 2024This study aims to compare the shaping ability of three systems using micro-computed tomography (micro-CT). Moderately-curved mesial canals of 36 mandibular molars were...
This study aims to compare the shaping ability of three systems using micro-computed tomography (micro-CT). Moderately-curved mesial canals of 36 mandibular molars were assigned to three groups (n = 24); Protaper Next (PTN, 0.25, 0.06), WaveOne Gold (WOG, 0.25, 0.07), TruNatomy (TRN, 0.25, 0.04), and instrumentation was performed. Pre- and post-micro-CT scans were obtained. Canal volume and surface, structure model index (SMI), centroid shift, canal transportation, and untouched canal were analyzed. One-way ANOVA and Student's t-test were used for statistics. There was no difference in SMI, centroid shift, and centering ability between the study groups (p > .05). Removed dentin and canal surface changes were lower in TRN, while untouched dentin walls were higher (p < .05). Cross-sections became more rounded (p < .05), but not significant between groups (p > .05). Considering the removed dentin by TRN, it can be used in critical dentin thickness, such as the danger zone (DZ). PTN, WOG, and WOG kept the original canal course similarly. Untouched dentin by TRN (41%) was wider than PTN and WOG, consequently, meticulous irrigation is recommended. TRN, which provides a controlled increase in canal volume, can be used in thin dentin such as the DZ, however, its use should be supported by copious irrigation and brushing considering the rate of untouched dentin walls. RESEARCH HIGHLIGHTS: TRN presented a higher untouched dentin wall compared to PTN and WOG. Canal volume and surface changes were the lowest in the TRN group. The centering abilities were similar in PTN, WOG, and TRN.
PubMed: 38813968
DOI: 10.1002/jemt.24613 -
American Journal of Dentistry Jun 2018To compare two systems used for conditioning the gingival sulcus and exposing the finish line before the final impression for a fixed denture: retraction cords and diode... (Clinical Trial)
Clinical Trial Randomized Controlled Trial
PURPOSE
To compare two systems used for conditioning the gingival sulcus and exposing the finish line before the final impression for a fixed denture: retraction cords and diode laser.
METHODS
All subjects participating in the study had healthy gingival and periodontal status before intervention for fixed prosthesis. 74 abutments for complete crown restoration were randomly divided into two groups for displacing the gingival sulcus before the final impression: gingival retraction cords (RC) and diode laser (DL). The height of the clinical crowns was measured by a blinded examiner in three points of the buccal surface (mesial, midline and distal) at four different times: after tooth preparation (T0), 15 days after tooth preparation, before exposing the finish line with RC or with DL (T1), 10 minutes after exposing the finish line (T2), and 15 days after the final impression was taken (T3). The amount of gingival retraction produced (ΔT2-T1) and restoration to baseline (ΔT3-T1) were calculated. Ease of technique and patient comfort were evaluated through the Visual Analog Scale. The time required to carry out the technique and bleeding during and after the conditioning procedure were also evaluated.
RESULTS
There was no difference between the two techniques with regard to the height differences: ΔT2-T1 was 0.65±0.33 for RC and 0.66#177;0.43 for the DL (P= 0.966), while ΔT3-T1 was 0.03#177;0.27 for RC and 0.02#177;0.46 for DL (P= 0.286). DL required less time, was easier for the operator and more comfortable than RC for the patient (all P<0.001).
CLINICAL SIGNIFICANCE
The amount of gingival retraction and restoration to baseline resulting from use of gingival retraction cords or diode laser technique is similar, but diode laser required less time, was simpler for the operator and was more comfortable to the patient than retraction cords.
Topics: Dental Impression Technique; Gingiva; Humans; Lasers, Semiconductor
PubMed: 30028930
DOI: No ID Found