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Development (Cambridge, England) Feb 2017The tooth root is an integral, functionally important part of our dentition. The formation of a functional root depends on epithelial-mesenchymal interactions and... (Review)
Review
The tooth root is an integral, functionally important part of our dentition. The formation of a functional root depends on epithelial-mesenchymal interactions and integration of the root with the jaw bone, blood supply and nerve innervations. The root development process therefore offers an attractive model for investigating organogenesis. Understanding how roots develop and how they can be bioengineered is also of great interest in the field of regenerative medicine. Here, we discuss recent advances in understanding the cellular and molecular mechanisms underlying tooth root formation. We review the function of cellular structure and components such as Hertwig's epithelial root sheath, cranial neural crest cells and stem cells residing in developing and adult teeth. We also highlight how complex signaling networks together with multiple transcription factors mediate tissue-tissue interactions that guide root development. Finally, we discuss the possible role of stem cells in establishing the crown-to-root transition, and provide an overview of root malformations and diseases in humans.
Topics: Animals; Bone Morphogenetic Proteins; Fibroblast Growth Factors; Hedgehog Proteins; Humans; Mice; Mice, Mutant Strains; Models, Dental; Odontogenesis; Signal Transduction; Stem Cells; Tooth Abnormalities; Tooth Crown; Tooth Root; Transforming Growth Factor beta; Wnt Signaling Pathway
PubMed: 28143844
DOI: 10.1242/dev.137216 -
Journal of Periodontology Oct 2019The incidence of a peri-implant soft tissue dehiscence/deficiency (PSTD) is not a rare finding. Despite multiple previous attempts aimed at correcting the PSTDs, a...
BACKGROUND
The incidence of a peri-implant soft tissue dehiscence/deficiency (PSTD) is not a rare finding. Despite multiple previous attempts aimed at correcting the PSTDs, a classification of these conditions has not yet been proposed. This lack in the literature may also lead to discrepancies in the reported treatment outcomes and thus misinform the clinician or the readers. The aim of the present article was therefore to present a classification of peri-implant PSTD at a single implant site.
METHODS
Four classes of PSTDs were discussed based on the position of the gingival margin of the implant-supported crown in relation to the homologous natural tooth. In addition, the bucco-lingual position of the implant head was also taken into consideration. Each class was further subdivided based on the height of the anatomical papillae.
RESULTS
Subsequently, for each respective category a surgical approach (including bilaminar techniques, the combined prosthetic-surgical approach or soft tissue augmentation with a submerged healing) was also suggested.
CONCLUSION
This paper provides a new classification system for describing PSTDs at single implant sites, with the appropriate recommended treatment protocol.
Topics: Crowns; Dental Implantation, Endosseous; Dental Implants, Single-Tooth; Dental Prosthesis, Implant-Supported; Esthetics, Dental; Tooth Crown; Treatment Outcome
PubMed: 31087334
DOI: 10.1002/JPER.18-0616 -
Medicina Oral, Patologia Oral Y Cirugia... Jul 2016Coronectomy is an alternative to complete removal of an impacted mandibular third molar. Most authors have recommended coronectomy to prevent damage to the inferior... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Coronectomy is an alternative to complete removal of an impacted mandibular third molar. Most authors have recommended coronectomy to prevent damage to the inferior alveolar nerve during surgical extraction of lower third molars. The present study offers a systematic review and metaanalysis of the coronectomy technique.
MATERIAL AND METHODS
A systematic review and meta-analysis was performed based on a PubMed and Cochrane databases search for articles published from 2014 and involving coronectomy of mandibular third molars located near the inferior alveolar nerve canal, with a minimum of 10 cases and a minimum follow-up period of 6 months. After application of the inclusion and exclusion criteria, a total of 12 articles were included in the study.
RESULTS AND DISCUSSION
Coronectomy results in significantly lesser loss of sensitivity of the inferior alveolar nerve and prevents the occurrence of dry socket. No statistically significant differences were observed in the incidence of pain and infection between coronectomy and complete surgical extraction. After coronectomy, the remaining tooth fragment migrates an average of 2 mm within two years.
CONCLUSIONS
Coronectomy is indicated when the mandibular third molar is in contact with the inferior alveolar nerve and complete removal of the tooth may cause nerve damage.
Topics: Humans; Mandible; Mandibular Nerve; Molar, Third; Tooth Crown; Tooth Extraction; Tooth, Impacted; Trigeminal Nerve Injuries
PubMed: 27031064
DOI: 10.4317/medoral.21074 -
PeerJ 2023Cusp patterning on living and extinct primate molar teeth plays a crucial role in species diagnoses, phylogenetic inference, and the reconstruction of the evolutionary... (Review)
Review
Cusp patterning on living and extinct primate molar teeth plays a crucial role in species diagnoses, phylogenetic inference, and the reconstruction of the evolutionary history of the primate clade. These studies rely on a system of nomenclature that can accurately identify and distinguish between the various structures of the crown surface. However, studies at the enamel-dentine junction (EDJ) of some primate taxa have demonstrated a greater degree of cusp variation and expression at the crown surface than current systems of nomenclature allow. In this study, we review the current nomenclature and its applicability across all the major primate clades based on investigations of mandibular crown morphology at the enamel-dentine junction revealed through microtomography. From these observations, we reveal numerous new patterns of lower molar accessory cusp expression in primates. We highlight numerous discrepancies between the expected patterns of variation inferred from the current academic literature, and the new patterns of expected variation seen in this study. Based on the current issues associated with the crown nomenclature, and an incomplete understanding of the precise developmental processes associated with each individual crown feature, we introduce these structures within a conservative, non-homologous naming scheme that focuses on simple location-based categorisations. Until there is a better insight into the developmental and phylogenetic origin of these crown features, these categorisations are the most practical way of addressing these structures. Until then, we also suggest the cautious use of accessory cusps for studies of taxonomy and phylogeny.
Topics: Animals; Phylogeny; Tooth Crown; Primates; Tooth; Molar
PubMed: 36650833
DOI: 10.7717/peerj.14523 -
Indian Journal of Dental Research :... 2018Damage to the inferior alveolar nerve (IAN) while extracting lower third molars is often caused by the intimate relationship between the nerve and the roots of the... (Comparative Study)
Comparative Study
AIM
Damage to the inferior alveolar nerve (IAN) while extracting lower third molars is often caused by the intimate relationship between the nerve and the roots of the teeth. The aim of this study was to compare the sequelae of coronectomy with odontectomy in impacted mandibular third molars.
PATIENTS AND METHODS
This study included thirty patients which were divided into two groups, Group-I (test group) including 15 patients undergoing coronectomy and Group-2 (control group) of 15 patients undergoing odontectomy. Investigations included digital orthopantomogram. The parameters for this study included pain, swelling, nerve paresthesia, trismus, postoperative infection, postoperative wound dehiscence, postoperative pocket depth, and migration.
RESULTS
In Group-1 (coronectomy group), the patients underwent follow-up for 6 months to evaluate migration of the retained mandibular third molar root which was in proximity with the IAN. There was a mean increase in migration when the distance from the inferior border of IAN until the apex of the retained mandibular third molar root was measured which was by 3.43 mm after 6 months of follow up.
CONCLUSION
On statistical analysis, the result in this study showed no statistical difference in both the groups in all the parameters that were taken.
Topics: Adolescent; Adult; Female; Follow-Up Studies; Humans; Male; Mandible; Mandibular Nerve; Molar, Third; Time Factors; Tooth Crown; Tooth Extraction; Tooth Migration; Tooth Root; Tooth, Impacted; Trigeminal Nerve Injuries; Young Adult
PubMed: 30409940
DOI: 10.4103/ijdr.IJDR_549_16 -
Journal of Dental Research Mar 2018The load-bearing dentoalveolar fibrous joint is composed of biomechanically active periodontal ligament (PDL), bone, cementum, and the synergistic entheses of PDL-bone... (Review)
Review
The load-bearing dentoalveolar fibrous joint is composed of biomechanically active periodontal ligament (PDL), bone, cementum, and the synergistic entheses of PDL-bone and PDL-cementum. Physiologic and pathologic loads on the dentoalveolar fibrous joint prompt natural shifts in strain gradients within mineralized and fibrous tissues and trigger a cascade of biochemical events within the widened and narrowed sites of the periodontal complex. This review highlights data from in situ biomechanical simulations that provide tooth movements relative to the alveolar socket. The methods and subsequent results provide a reasonable approximation of strain-regulated biochemical events resulting in mesial mineral formation and distal resorption events within microanatomical regions at the ligament-tethered/enthesial ends. These biochemical events, including expressions of biglycan, decorin, chondroitin sulfated neuroglial 2, osteopontin, and bone sialoprotein and localization of various hypertrophic progenitors, are observed at the alkaline phosphatase-positive widened site, resulting in mineral formation and osteoid/cementoid layers. On the narrowed side, tartrate-resistant acid phosphatase regions can lead to a sequence of clastic activities resulting in resorption pits in bone and cementum. These strain-regulated biochemical and subsequently biomineralization events in the load-bearing periodontal complex are critical for maintenance of the periodontal space and overall macroscale joint biomechanics.
Topics: Adaptation, Physiological; Animals; Biomechanical Phenomena; Bone and Bones; Dental Cementum; Dental Stress Analysis; Humans; Mastication; Mouth Diseases; Periodontal Ligament; Tooth Crown
PubMed: 29364757
DOI: 10.1177/0022034517744556 -
Scientific Reports Nov 2023For restoration of extensively damaged teeth preprosthetic treatment measures are necessary. Crown lengthening and extrusion affect the prospective crown-root ratio...
For restoration of extensively damaged teeth preprosthetic treatment measures are necessary. Crown lengthening and extrusion affect the prospective crown-root ratio (CRR). The subject of this in vitro study was to compute CRRs for both treatment approaches. 120 human maxillary central extracted incisors were measured. Measurements were calculated for five treatment groups: C (control), E-2 mm (extrusion of 2 mm), E-4 mm (extrusion of 4 mm), CL-2 mm (crown lengthening of 2 mm), and CL-4 mm (crown lengthening of 4 mm). Tooth (TL), root (RL), and crown lengths (CL) were measured from mesial (m) and facial (f) cemento-enamel junction (CEJ), and respective anatomic (CRR) and effective crown-root ratios (eCRR) were calculated. Following CRR values were computed for C: CRR-m = 0.4 ± 0.1, CRR-f = 0.7 ± 0.1. All crown-root ratios were lower (more favourable) for extrusion compared to crown lengthening (p < 0.001). ECRRs were higher than anatomic CRRs. CRR at mesial CEJ was significantly lower than CRR with facial CEJ as reference (p < 0.001). Mesial measurement-based calculations of CRR typically based on radiographic images should be interpreted with caution as they underestimate the eCRR. CRR can be expected as lower, i.e. more favourable, when teeth are extruded than crown lengthened.
Topics: Humans; Crown Lengthening; Prospective Studies; Crowns; Incisor; Tooth Cervix; Tooth Crown; Tooth Root
PubMed: 37919362
DOI: 10.1038/s41598-023-46354-y -
Anatomical Record (Hoboken, N.J. : 2007) Dec 2020Tooth developmental stage evaluation is important in dental and chronological age estimation, and it is important for accurate diagnoses and appropriate treatment in...
Tooth developmental stage evaluation is important in dental and chronological age estimation, and it is important for accurate diagnoses and appropriate treatment in dental practice. It is routinely assessed by clinical observations and radiographic techniques. This study aimed at ascertaining tooth developmental stage judgments made by examiners and Mimics software according to the Nolla method with radiographs. Meanwhile, the true tooth developmental stages would be explored with histological analysis. Twenty freshly slaughtered porcine heads were collected and hemisected, and both the left and right mandibular samples were numbered. The developmental stages of the second and third permanent molars (M2 and M3) were evaluated by examiners and Mimics software analysis. The ratio of the radiopaque calcified area to the dental follicle (RCA/DF) at different stages was calculated. Both non-decalcified and decalcified samples were processed for histologic observation. The results showed significant differences between RCA/DF ratios from different developmental stages. There was a high positive correlation between the examiners' evaluation results and Mimics analysis results. Radiograph judgments and histology observation results were consistent from Stages 2-6. However, radiograph images of Stage 1 samples showed only crypts present, while under a surgical operating microscope, a bell-shaped tooth germ was observed. This was also confirmed by normal and hard tissue histology. In conclusion, radiograph judgments made by either examiners or Mimics software were both reliable. Mimics analysis can be a useful tool in evaluating tooth developmental stages. However, judgments need to be made cautiously in early developmental stages.
Topics: Animals; Image Processing, Computer-Assisted; Mandible; Odontogenesis; Swine; Tomography, X-Ray Computed; Tooth; Tooth Crown
PubMed: 31930691
DOI: 10.1002/ar.24366 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Jun 2023Post-and-core crown is one of the most common forms of restoration of tooth after root canal therapy (RCT). Infection control is the core objective of RCT, which is...
Post-and-core crown is one of the most common forms of restoration of tooth after root canal therapy (RCT). Infection control is the core objective of RCT, which is usually well realized by endodontists. However, many prosthodontists often neglect the infection control of the tooth and the maintenance of the curative effect of RCT during the process of post-and-core crown, which may lead to the failure of the final restoration. The concept of integrated crown-root treatment advocated recently requires clinicians to consider the RCT and final restoration as a whole, rather than simply divided into two parts-endodontic treatment and restorative treatment. As the core content of integrated crown-root treatment, infection control should be taken seriously by clinicians and implemented throughout the whole treatment process, especially in the restorative treatment that is easily overlooked after RCT. Therefore, this article describes the infection control of post-and-core crown restoration, classifies the tooth requiring post-and-core crown restoration, and puts forward the measures of infection control before and during post-and-core crown restoration, in order to provide reference and guidance for clinical practice.
Topics: Humans; Crowns; Tooth Crown; Post and Core Technique; Root Canal Therapy; Infection Control; Tooth Fractures
PubMed: 37277789
DOI: 10.7518/hxkq.2023.2023030 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Oct 2019Crown lengthening is one of the most common surgeries in clinical practice. Under the premise of ensuring the biologic width, the adequate crown is exposed by resecting... (Review)
Review
Crown lengthening is one of the most common surgeries in clinical practice. Under the premise of ensuring the biologic width, the adequate crown is exposed by resecting the periodontal soft tissue and (or) hard tissue to meet the prosthodontic and (or) aesthetic requirements. Considering the various advantages of oral laser, such as safe, precise, minimally invasive and comfort, laser has become a promising technology which can be used to improve the traditional crown lengthening. In this review, the principles and characteristics of laser application in crown lengthening, especially in the minimally invasive or flapless crown lengthening will be reviewed. Its pros and cons will also be discussed.
Topics: Crown Lengthening; Crowns; Esthetics, Dental; Tooth; Tooth Crown
PubMed: 31721507
DOI: 10.7518/hxkq.2019.05.019