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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 -
Journal of Anatomy Sep 2016Human molars exhibit a type of metameric variation, which is the difference in serially repeated morphology within an organism. Various theories have been proposed to...
Human molars exhibit a type of metameric variation, which is the difference in serially repeated morphology within an organism. Various theories have been proposed to explain how this variation is brought about in the molars. Actualistic data that support the theories, however, are still relatively scarce because of methodological limitations. Here we propose new methods to analyse detailed tooth crown morphologies. We applied morphometric mapping to the enamel-dentine junction of human maxillary molars and examined whether odontogenetic models were adaptable to human maxillary molars. Our results showed that the upper first molar is phenotypically distinct among the maxillary molars. The average shape of the upper first molar is characterized by four well-defined cusps and precipitous surface relief of the occlusal table. On the other hand, upper third molar is characterized by smooth surface relief of the occlusal table and shows greater shape variation and distinct distribution patterns in morphospace. The upper second molar represents an intermediate state between first and third molar. Size-related shape variation was investigated by the allometric vector analysis, and it appeared that human maxillary molars tend to converge toward the shape of the upper first molar as the size increases. Differences between the upper first molar and the upper second and third molar can thus be largely explained as an effect of allometry. Collectively, these results indicate that the observed pattern of metameric variation in human molars is consistent with odontogenetic models of molar row structure (inhibitory cascade model) and molar crown morphology (patterning cascade model). This study shows that morphometric mapping is a useful tool to visualize and quantify the morphological features of teeth, which can provide the basis for a better understanding of tooth evolution linking morphology and development.
Topics: Humans; Molar; X-Ray Microtomography
PubMed: 27098351
DOI: 10.1111/joa.12482 -
Scientific Reports Jun 2022Tooth development is governed largely by epithelial-mesenchymal interactions and is mediated by numerous signaling pathways. This type of morphogenetic processes has...
Tooth development is governed largely by epithelial-mesenchymal interactions and is mediated by numerous signaling pathways. This type of morphogenetic processes has been explained by reaction-diffusion systems, especially in the framework of a Turing model. Here we focus on morphological and developmental differences between upper and lower molars in mice by modeling 2D pattern formation in a Turing system. Stripe vs. spot patterns are the primary types of variation in a Turing model. We show that the complexity of the cusp cross-sections can distinguish between stripe vs. spot patterns, and mice have stripe-like upper and spot-like lower molar morphologies. Additionally, our computational modeling that incorporates empirical data on tooth germ growth traces the order of cusp formation and relative position of the cusps in upper and lower molars in mice. We further propose a hypothetical framework of developmental mechanism that could help us understand the evolution of the highly variable nature of mammalian molars associated with the acquisition of the hypocone and the increase of lophedness.
Topics: Animals; Mammals; Mice; Molar; Morphogenesis; Odontogenesis; Signal Transduction; Tooth Germ
PubMed: 35701484
DOI: 10.1038/s41598-022-13539-w -
Head & Face Medicine Mar 2023This retrospective cohort study aimed to compare treatment results between bilateral extraction of upper second molars (M2) and first premolars (P1) in terms of... (Comparative Study)
Comparative Study
BACKGROUND
This retrospective cohort study aimed to compare treatment results between bilateral extraction of upper second molars (M2) and first premolars (P1) in terms of treatment timing, cephalometry, upper third molar alignment and relapse in the long-term.
METHODS
Fifty-three consecutively treated Caucasian patients with a brachyfacial pattern, skeletal class I and dental class II requiring extraction in the maxilla due to crowding were retrospectively divided into group I (M2 extracted; N = 31) and II (P1 extracted; N = 22). Fixed appliances were inserted after extraction and after distalisation of the first molars in group I. Post-treatment lateral cephalograms were digitally analysed and compared between groups. Six to seven years later relapse and success of upper third molar alignment were clinically evaluated as well as orthodontic treatment duration, pre-treatment age and gender recorded.
RESULTS
After debonding patients with second molar extraction showed significantly smaller values for the Wits-appraisal, but higher values for index and facial axis. Extracting first premolars caused significantly more retroinclination/-position of anterior teeth and an increased profile concavity, more relapse and less successful alignment of upper third molars. Orthodontic treatment duration, pre-treatment age and gender were not significantly different between groups.
CONCLUSIONS
Bilateral extraction of upper first premolars or second molars may solve dental crowding in skeletal class I dental class II patients with a brachyfacial growth pattern. Upper second molar extraction seems to affect maxillary third molar alignment, long-term stability and dental and soft-tissue cephalometric parameters positively, but no intervention proved to be clearly superior.
Topics: Humans; Bicuspid; Malocclusion; Molar; Retrospective Studies; Treatment Outcome
PubMed: 36882841
DOI: 10.1186/s13005-023-00353-6 -
American Journal of Orthodontics and... Aug 2021Uprighting mesially tipped molars is often a necessary step before implant placement. However, the orthodontic treatment can be lengthy and discourage patients from...
INTRODUCTION
Uprighting mesially tipped molars is often a necessary step before implant placement. However, the orthodontic treatment can be lengthy and discourage patients from choosing implant prostheses. Periodontally accelerated osteogenic orthodontics is reported to facilitate molar movements. This study aimed to evaluate the biomechanical effects of various corticotomy and osteotomy approaches on the uprighting of a mesially tipped mandibular second molar in a 3-dimensional finite element analysis model.
METHODS
The initial tooth displacement and periodontal ligament (PDL) strain in 9 finite element analysis models with various corticotomy and osteotomy simulations were compared under 3 intended tooth movement scenarios: distal crown tipping, mesial root movement with restraints, and mesial root movement without restraints.
RESULTS
Corticotomy or osteotomy approaches altered the tooth displacement and the PDL strain in all 3 intended molar uprighting scenarios. The 2 most extensive surgical approaches, the combined mesial and distal osteotomy with horizontal corticotomy and the circumferential corticotomy at root apex level, resulted in increased tooth movement but had a distinct impact on PDL strain.
CONCLUSIONS
It was revealed that different combinations of corticotomy and osteotomy had a biomechanical impact on orthodontic molar uprighting movements.
Topics: Finite Element Analysis; Humans; Molar; Osteotomy; Tooth Movement Techniques; Tooth Root
PubMed: 34099344
DOI: 10.1016/j.ajodo.2020.06.034 -
Journal of Orthodontics Dec 2022To find the effect of extraction of the lower first permanent molar in children (aged 8-11 years) on the position and angle of the developing third molar.
OBJECTIVE
To find the effect of extraction of the lower first permanent molar in children (aged 8-11 years) on the position and angle of the developing third molar.
DESIGN
Retrospective radiographic analysis.
PARTICIPANTS
Two cohorts of participants were identified: an extraction group, who had extraction of one or more first permanent molars aged 8-11 years; and a non-extraction group, who retained all mandibular teeth. Both cohorts previously had panoramic radiographs taken at mean ages of 9.7 years (T1), before extraction, and 12.12 years (T2). In total, there were 61 third molars with an associated extracted first permanent molar and 60 third molars with an associated retained first permanent molar.
METHODS
A digital radiographic analysis was carried out on the panoramic radiographs to measure the movement of the third molar, vertically and horizontally, and its angle. The magnification of the T1 and T2 radiographs was calibrated. Reliability of the radiographic analysis was confirmed via intra- and inter-rater reliability tests. The extraction and non-extraction groups were compared via independent sample tests.
RESULTS
The third molar moved significantly more mesial in the extraction group ( < 0.001) and the angle uprighted significantly more than the non-extraction group ( < 0.001). Vertically, the third molar moved inferiorly in both cohorts with no significant difference.
CONCLUSION
In the developing dentition, extraction of the lower first permanent molar encouraged mesial movement and uprighting of the developing third molar. This may improve the likelihood of future eruption of the third molar.
Topics: Humans; Child; Molar, Third; Retrospective Studies; Reproducibility of Results; Mandible; Radiography, Dental, Digital; Radiography, Panoramic; Molar; Tooth Eruption; Tooth Extraction
PubMed: 35475356
DOI: 10.1177/14653125221093086 -
Journal of Morphology Nov 2015The evolution of mammalian molars has been marked by transitions representing significant changes in shape and function. One such transition is the addition and...
The evolution of mammalian molars has been marked by transitions representing significant changes in shape and function. One such transition is the addition and elaboration of the talon, the distolingual region of the ancestral tribosphenic upper molar of therian mammals and some extinct relatives. This study uses suborder Microchiroptera as a case study to explore the adaptive implications of the expansion of the talon on the tribosphenic molar, specifically focusing on the talon's role in the compression and shear of food during breakdown. Three-dimensional computer renderings of casts of the upper left first molars were created for microbat species of a variety of dietary categories (frugivore, etc.) and physical properties of food (hard and soft). Relief Index (RFI) was measured to estimate the topography and function of the whole tooth and of the talon and trigon (the remaining primitive tribosphenic region) individually, in order to examine 1) how the shape of the whole tooth, trigon, and talon reflects the compromise between their crushing and shearing functions, 2) how whole tooth, trigon, and talon function differs according to diet, and 3) how the presence of the talon affects overall molar function. Results suggest that RFI of both the whole tooth and the trigon varies according to dietary groups, with frugivores having greater crushing function when compared with the other groups. The talon, however, consistently has low RFI (a flatter topography), and its presence lowers the RFI of the whole tooth across all dietary categories, suggesting that the talon is primarily functioning in crushing during food breakdown. The potential benefits of a crushing talon for microbats of various dietary groups are discussed.
Topics: Analysis of Variance; Animals; Biological Evolution; Biomechanical Phenomena; Chiroptera; Diet; Hardness; Molar; Phylogeny
PubMed: 26473768
DOI: 10.1002/jmor.20424 -
The Journal of Clinical Pediatric... Jan 2022The extraction of permanent first molar (PFM) teeth with poor prognosis allows the build of a new-and-ideal occlusion with the spontaneous movement of the healthy second...
PURPOSE
The extraction of permanent first molar (PFM) teeth with poor prognosis allows the build of a new-and-ideal occlusion with the spontaneous movement of the healthy second and third molars by taking advantage of the patient's development. This study aimed to evaluate dentists' knowledge level about controlled tooth extractions and determine their information needs.
STUDY DESIGN
The survey, consisting of 9 questions about balance and compensation extractions, was prepared on Google Forms and sent via email to dentists.
RESULTS
The questionnaire was sent to 3137 dentists and 472 (15.04%) of them answered. While deciding on PFM extraction, the rate of those who checked the presence of permanent 3rd molar tooth was found to be 64.4%. Although 79% of pedodontists stated that they knew about balance extractions, only 60.9% of them apply it in the clinic. After maxillary PFM extraction, the rate of oral and maxillofacial surgeons who think that "mandibular PFM over-erupt" was 92.8%, and the rate of orthodontists was 68.7%. 87.1% of the participants stated that they needed more information about controlled extractions.
CLINICAL SIGNIFICANCE
It is possible to raise awareness, encourage the common and follow-up of correct clinical practices, and avoid complications; by adding controlled extractions to the undergraduate education program.
Topics: Dentists; Health Knowledge, Attitudes, Practice; Humans; Mandible; Molar; Molar, Third
PubMed: 35311981
DOI: 10.17796/1053-4625-46.1.3 -
The Journal of Evidence-based Dental... Dec 2022To compare the clinical and radiographic outcomes of pulpotomies in primary molars using bioactive endodontic materials and ferric sulfate. (Meta-Analysis)
Meta-Analysis Review
COMPARING THE CLINICAL AND RADIOGRAPHIC OUTCOMES OF PULPOTOMIES IN PRIMARY MOLARS USING BIOACTIVE ENDODONTIC MATERIALS AND FERRIC SULFATE - A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMIZED CLINICAL TRIALS.
OBJECTIVE
To compare the clinical and radiographic outcomes of pulpotomies in primary molars using bioactive endodontic materials and ferric sulfate.
DESIGN
The search was conducted in PubMed, Ebscohost, ProQuest, and Scopus databases till June 2021. Children undergoing pulpotomy therapy in primary molars treated with ferric sulfate (FS) and bioactive endodontic materials were evaluated for clinical and radiographic success. Meta-analysis was performed on a random-effects model to assess the success at 6,12,18, and 24 months. The quality of studies was evaluated using the Cochrane risk of bias tool for randomized trials RESULTS: No significant difference was observed between Mineral trioxide aggregate (MTA) and FS at 24 months for both clinical [RR0.98 (95%CI 0.15,6.34), I = 0%] and radiographic [RR0.74 (95%CI: 0.23,2.43), I = 0%] success. At 6 months [RR1.36 (95%CI: 0.10,19.34), I = 33%], no difference was observed in the clinical [RR1.00 (95%CI: 0.95,1.05), I = 0%] and radiographic success [RR0.99 (95%CI: 0.88,1.11), I = 51%] between Biodentine (BD), FS and radiographic success of calcium enriched cement and FS [RR0.25 (95%CI: 0.03, 2.22), I = 0%].
CONCLUSION
Amongst bioactive materials, MTA and FS demonstrated equal success rates in both clinical and radiographic outcomes with follow-up periods of up to 24 months. Future, high-quality trials are required to verify the result of the current review.
Topics: Child; Humans; Tooth, Deciduous; Molar; Randomized Controlled Trials as Topic; Pulpotomy; Treatment Outcome
PubMed: 36494111
DOI: 10.1016/j.jebdp.2022.101770 -
International Journal of Environmental... May 2020The purpose of the presented Artificial Intelligence (AI)-tool was to automatically segment the mandibular molars on panoramic radiographs and extract the molar...
The purpose of the presented Artificial Intelligence (AI)-tool was to automatically segment the mandibular molars on panoramic radiographs and extract the molar orientations in order to predict the third molars' eruption potential. In total, 838 panoramic radiographs were used for training ( = 588) and validation ( = 250) of the network. A fully convolutional neural network with ResNet-101 backbone jointly predicted the molar segmentation maps and an estimate of the orientation lines, which was then iteratively refined by regression on the mesial and distal sides of the segmentation contours. Accuracy was quantified as the fraction of correct angulations (with predefined error intervals) compared to human reference measurements. Performance differences between the network and reference measurements were visually assessed using Bland-Altman plots. The quantitative analysis for automatic molar segmentation resulted in mean IoUs approximating 90%. Mean Hausdorff distances were lowest for first and second molars. The network angulation measurements reached accuracies of 79.7% [-2.5°; 2.5°] and 98.1% [-5°; 5°], combined with a clinically significant reduction in user-time of >53%. In conclusion, this study validated a new and unique AI-driven tool for fast, accurate, and consistent automated measurement of molar angulations on panoramic radiographs. Complementing the dental practitioner with accurate AI-tools will facilitate and optimize dental care and synergistically lead to ever-increasing diagnostic accuracies.
Topics: Artificial Intelligence; Dentists; Humans; Molar; Professional Role; Radiography, Panoramic
PubMed: 32466156
DOI: 10.3390/ijerph17103716