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The Angle Orthodontist Jan 2022To assess the changes in alveolar bone of the mandibular second molars following molar protraction and investigate the factors associated with the alveolar bone changes.
OBJECTIVES
To assess the changes in alveolar bone of the mandibular second molars following molar protraction and investigate the factors associated with the alveolar bone changes.
MATERIALS AND METHODS
Cone-beam computed tomography of 29 patients (mean age 22.0 ± 4.2 years) who had missing mandibular premolars or first molars and underwent molar protraction were reviewed. Alveolar bone level was measured as the distance from the cementoenamel junction at six points, buccal, lingual, mesiobuccal (MB), mesiolingual (ML), distobuccal (DB), and distolingual (DL), of the second molars at pretreatment (T0) and after molar protraction (T1). Factors associated with alveolar bone changes at the distal and mesial of the second molars were assessed.
RESULTS
Mean alveolar bone changes ranged from -1.2 mm (bone apposition) to 0.8 mm (bone resorption). The presence of a third molar impaction at T0 (P < .001), third molar angulation at T0 (P < .001), and Nolla's stage of third molar at T0 (P = .005) were significantly associated with alveolar bone level changes distal to the second molars. Treatment duration (P = .028) was significantly associated with alveolar bone level changes mesial to the second molar.
CONCLUSIONS
Patients with impacted third molars, third molars at an earlier stage of development, and mesially angulated third molars at pretreatment may have less alveolar bone resorption distal to the second molars following protraction. Patients with increased treatment time may have reduced alveolar bone resorption mesial to the second molars.
Topics: Adolescent; Adult; Bicuspid; Cone-Beam Computed Tomography; Humans; Mandible; Molar; Molar, Third; Tooth, Impacted; Young Adult
PubMed: 34587241
DOI: 10.2319/022321-147.1 -
Nigerian Journal of Clinical Practice Jun 2023The aim of this clinic study was to investigate the effect of piezoincision on the rate of mandibular molar mesialization using clinical, radiological, and biochemical... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND AND AIM
The aim of this clinic study was to investigate the effect of piezoincision on the rate of mandibular molar mesialization using clinical, radiological, and biochemical methods.
MATERIALS AND METHODS
Twenty-one patients requiring mandibular first molar extraction and second molar mesialization were included in the study which was designed as split-mouth study. Piezoincision was performed on the buccal surface of alveolar bone following regional alignment to the randomly selected side. 150 g of force was applied to the second molar teeth using mini-screw-supported anchorage after the piezoincision. Cone beam computed tomography (CBCT), gingival crevicular fluid (GCF) and digital model records of the patients were obtained. Two- and three-dimensional measurements were performed and compared on the CBCT images in a study which lasted 24 weeks.
RESULTS
According to the model analysis, the canine-second molar distance was consistently reduced and a greater decrease was measured on the experimental group (p < 0.05). Second molar mesial rotations increased in both groups (p < 0.001). Two-dimensional measurements on CBCT images showed increased mesial and buccal tipping of second molars in experimental group (p < 0.001). There was a significant increase in mesialization measurements of experimental group (p < 0.001). Three-dimensional measurements on the CBCT images showed a decrease of root length in both groups (p < 0.001), and a greater decrease was found in the experimental group (p < 0.001). When intra-group changes in GCF results were examined, it was observed that there was no significant change in osteoprotegerin (OPG) values over time in experimental group (p = 0.148).
CONCLUSION
The piezoincision technique provided acceleration of mandibular molar mesialization and did not cause further damage to the buccal alveolar bone. Piezoincision can be used as a safe method in the mandibular molar region.
Topics: Mandible; Molar; Tooth; Face; Cone-Beam Computed Tomography
PubMed: 37470644
DOI: 10.4103/njcp.njcp_657_22 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Jun 2021With a case of mesial impaction of maxillary first and second molar, the mechanical analysis and clinical applications of a self-made helical spring for the uprighting...
With a case of mesial impaction of maxillary first and second molar, the mechanical analysis and clinical applications of a self-made helical spring for the uprighting treatment of mesial impacted molars was introduced.
Topics: Humans; Mandible; Maxilla; Molar; Molar, Third; Tooth Movement Techniques; Tooth, Impacted
PubMed: 34041888
DOI: 10.7518/hxkq.2021.03.018 -
Medicina (Kaunas, Lithuania) Mar 2021Endodontic microsurgery is a highly predictable treatment option in most cases when conventional endodontic treatment is not feasible. Nevertheless, mandibular molars... (Review)
Review
Endodontic microsurgery is a highly predictable treatment option in most cases when conventional endodontic treatment is not feasible. Nevertheless, mandibular molars are still considered by clinicians to be the most difficult type of teeth, with the lowest success rate. In recent years, endodontic microsurgery has been attempted more frequently with the emergence of modern cutting-edge technologies such as dental operating microscopes, various microsurgical instruments, and biocompatible materials, and the success rate is increasing. This review describes the current state of the art in endodontic microsurgical techniques and concepts for mandibular molars. Notably, this review highlights contemporary equipment, technology, and materials.
Topics: Humans; Microsurgery; Molar
PubMed: 33809673
DOI: 10.3390/medicina57030270 -
Odontology Jan 2022The shaping outcomes after instrumentation with rotary and reciprocating glide path and shaping systems were evaluated through micro-computed tomography (Micro-CT)....
The shaping outcomes after instrumentation with rotary and reciprocating glide path and shaping systems were evaluated through micro-computed tomography (Micro-CT). Thirty extracted maxillary first molars were selected. Mesio-buccal canals were randomized into two groups (n = 15): rotary system ProGlider and ProTaper Next X1, X2 (PG-PTN) and reciprocating system WaveOne Gold Glider and WaveOne Gold Primary (WOGG-WOG). Specimens were micro-CT scanned before, after glide path and after shaping. Increase in canal volume and surface area, percentage of removed dentin from the inner curvature, centroid shift and canal geometry variation through ratio of diameter ratios (RDR) and ratio of cross-sectional areas (RA) were measured in the apical and coronal levels and at the point of maximum curvature. The number of pecking motions needed to reach the working length (WL) was recorded. One-way ANOVA and post hoc Turkey-Kramer tests were used (p < 0.05). Post-glide path analysis revealed that in the coronal third, RDR was more favorable to PG and centroid shift was lower for WOGG in the apical third. Post-shaping analysis showed a reduced removal of dentin and a more favorable RA for PTN at point of maximum curvature. The number of pecking motions up to WL resulted in different between groups both for glide path and shaping phases. Despite a higher dentin removal for reciprocating instruments at the point of maximum curvature, both systems seemed to produce well-centered glide path and shaping outcomes. Rotary and reciprocating systems seemed able to respect the original canal anatomy.
Topics: Dental Pulp Cavity; Equipment Design; Gold; Molar; Root Canal Preparation; X-Ray Microtomography
PubMed: 34173078
DOI: 10.1007/s10266-021-00631-2 -
Annals of Anatomy = Anatomischer... Jun 2024Human sexual dimorphism is associated with many biological characteristics, including dental variables.
BACKGROUND
Human sexual dimorphism is associated with many biological characteristics, including dental variables.
OBJECTIVES
To investigate if molars fused roots present sex-associated differences.
METHODS
Panoramic radiographs were used to investigate the frequency and distribution of permanent molars fused roots. Only patients with all first and second permanent molars were included. Third molars were not investigated. Any molar with roots fused apical to the usual furcal position were considered molar fused roots. Comparisons between males and females were performed using chi-square or Fisher's and Mann-Whitney tests and the established alpha was 5% (p<0.05). Sex-differential liability models were also proposed.
RESULTS
A total of 84 males and 86 females were included and 1360 molars were analyzed. Among them, 46 (26.06%) present at least one molar with fused root. Second maxillary molars were the most affected teeth. There was an association between sex and molars with fused roots. Females had a 3.4 higher chance to present fused roots than males (OR=3.4, CI 95% 1.6-6.8; p=0.0008). The female: male ratio of molars with fused roots was 2.5:1. The number of molars with fused roots ranged from 1 to 6 per patient, and the mean number of Females presented more molars with fused roots (mean = 1.01; standard deviation = 1.52) than males (mean = 0.31; standard deviation = 0.85) (p<0.05).
CONCLUSIONS
Molar fused root of permanent teeth presents sex-associated differences, in which females are more affected than males. Our results support sex-differential liability models for molars fused roots.
Topics: Humans; Male; Female; Molar; Tooth Root; Sex Characteristics; Adult; Radiography, Panoramic; Young Adult; Adolescent; Middle Aged; Fused Teeth
PubMed: 38460859
DOI: 10.1016/j.aanat.2024.152245 -
The Journal of Prosthetic Dentistry Jul 2023Mandibular second molars have variable root, pulp chamber floor, and radicular groove morphologies, potentially affecting residual dentin thickness and post placement...
Microcomputed tomography analysis of the radicular residual dentin thickness in mandibular second molars after virtual fiber post placement: Identification of danger zones.
STATEMENT OF PROBLEM
Mandibular second molars have variable root, pulp chamber floor, and radicular groove morphologies, potentially affecting residual dentin thickness and post placement suitability. However, an identification of the danger zones is lacking.
PURPOSE
The purpose of this in vitro study was to investigate the residual dentin thickness in the danger zone of mandibular second molars after virtual fiber post placement by using a simulation method based on microcomputed tomography (μCT).
MATERIAL AND METHODS
A total of 84 extracted mandibular second molars were scanned using μCT and classified according to root morphology (separate or fused) and pulp chamber floor morphologies (C-shaped, non-C-shaped, or no pulp chamber floor). Fused-root mandibular second molars were further classified based on the radicular groove type (V-, U-, or Ω-shaped). All specimens were accessed, instrumented, and rescanned with μCT. Two types of commercial fiber posts were also scanned. Clinical fiber post placement was simulated in all prepared canals by using a multifunctional software program. The minimum residual dentin thickness of each root canal was measured and analyzed by using nonparametric tests to identify the danger zone. Perforation rates were calculated and recorded.
RESULTS
Larger fiber posts decreased minimum residual dentin thickness (P<.05) and increased perforation rate. In regard to mandibular second molars with separate roots, the distal root canal exhibited a significantly higher minimum residual dentin thickness than the mesiobuccal and mesiolingual root canals (P<.05). However, no significant difference in minimum residual dentin thickness was found between the different canals in fused-root mandibular second molars with C-shaped pulp chamber floors (P<.05). Fused-root mandibular second molars with Ω-shaped radicular grooves had a lower minimum residual dentin thickness than those with V-shaped radicular grooves (P<.05) and demonstrated the highest perforation rate.
CONCLUSIONS
The morphologies of the root, pulp chamber floor, and radicular groove were correlated with residual dentin thickness distribution in mandibular second molars after fiber post placement. A comprehensive understanding of mandibular second molar morphology is essential for determining the suitability of post-and-core crown restorations after endodontic treatment.
Topics: Humans; X-Ray Microtomography; Tooth Root; Mandible; Dental Pulp Cavity; Molar; Dentin
PubMed: 37210223
DOI: 10.1016/j.prosdent.2023.04.010 -
Human Biology 2021Dental development has been used to assess whether an individual may be below or above an age that serves as a legal threshold. This study used development of the first...
Dental development has been used to assess whether an individual may be below or above an age that serves as a legal threshold. This study used development of the first and second mandibular molars from a large sample of individuals (N = 2,676) to examine the age threshold for minimum age of criminal responsibility. A bivariate ordered probit model was applied to dental scores following the Moorrees et al. (1963) system, with the addition of a crypt-absent/present stage. Then a 10-fold cross-validation within each of the sexes showed that the bivariate models produce unbiased estimates of age but are heteroskedastic (with increasing spread of the estimates against actual age). To address the age threshold problem, a normal prior centered on the threshold is assumed, and the product of the prior and the likelihood is integrated up to the age threshold and again starting at the age threshold. The ratio of these two integrals is a Bayes factor, which because the prior is symmetric around the threshold, can also be interpreted as the posterior odds that an individual is over versus under the age threshold. It was necessary to assume an unreasonably high standard deviation of age in the prior to achieve posterior odds that were well above "evens." These results indicate that dental developmental evidence from the first and second molars is of limited use in examining the question of whether an individual is below or over the minimum age of criminal responsibility. As the third molar is more variable in its development than the first two molars, the question of dental evidence regarding the age of majority (generally 18 years) remains problematic.
Topics: Adolescent; Age Determination by Teeth; Bayes Theorem; Humans; Molar; Molar, Third; Radiography, Panoramic
PubMed: 35338702
DOI: 10.13110/humanbiology.93.1.02 -
General Dentistry 2021The success of root canal treatment depends on complete debridement of pulp tissue from the root canals. Therefore, a thorough knowledge of unusual anatomical findings... (Review)
Review
The success of root canal treatment depends on complete debridement of pulp tissue from the root canals. Therefore, a thorough knowledge of unusual anatomical findings is of utmost importance. Although the majority of mandibular molars present with 2 roots (mesial and distal) and 3 or 4 root canals, the number of roots and root canals in individual molars may vary. An extra root is called a radix entomolaris if it is located distolingually and a radix paramolaris if located mesiobuccally. This article presents a series of 5 cases of radix entomolaris and radix paramolaris in mandibular first, second, and third molars and reviews the literature on these morphologic variations.
Topics: Dental Pulp Cavity; Humans; Mandible; Molar; Root Canal Therapy; Tooth Root
PubMed: 33908881
DOI: No ID Found -
Proceedings of the National Academy of... Jun 2021Exposure to adversity can accelerate biological aging. However, existing biomarkers of early aging are either costly and difficult to collect, like epigenetic...
Exposure to adversity can accelerate biological aging. However, existing biomarkers of early aging are either costly and difficult to collect, like epigenetic signatures, or cannot be detected until late childhood, like pubertal onset. We evaluated the hypothesis that early adversity is associated with earlier molar eruption, an easily assessed measure that has been used to track the length of childhood across primates. In a preregistered analysis ( = 117, ages 4 to 7 y), we demonstrate that lower family income and exposure to adverse childhood experiences (ACEs) are significantly associated with earlier eruption of the first permanent molars, as rated in T2-weighted magnetic resonance images (MRI). We replicate relationships between income and molar eruption in a population-representative dataset (National Health and Nutrition Examination Survey; = 1,973). These findings suggest that the impact of stress on the pace of biological development is evident in early childhood, and detectable in the timing of molar eruption.
Topics: Adverse Childhood Experiences; Child; Child, Preschool; Female; Humans; Income; Magnetic Resonance Imaging; Male; Molar; Tooth Eruption
PubMed: 34103399
DOI: 10.1073/pnas.2105304118