Tooth Form Research Articles

“The Study Of Eruption Of Teeth In Children From Birth To 12 Years Of Age In Western Maharashtra Region.”

Human beings show 2 sets of dentition- deciduous and permanent2. Variation of tooth has been an enduring interest to clinical practitioner as well as from anthropological and forensic point of view7 . These variations in the form of teeth are characteristics of race, are of anthropological, genetic and forensic interest.2,7hence studies have been done using teeth for age, sex determination1,8 . As existing eruption schedule of dentition is based on western population this study is done in western Maharashtra region to find out variation in time number, form and pattern of eruption in deciduos and permanent teeth as well as in males and females.

General dentists’ treatment plans in response to cosmetic complains; a field study using unannounced-standardized-patient

BackgroundThis field study explored general dentists' treatment plans in response to the request for cosmetic services of an unannounced standardized patient (USP) in Mashhad, Iran. MethodsThe researcher, as a USP, visited 24 and 23 offices in a high-income and a low-income area, respectively. The primary complaint was that, according to her friend's comments, a dental student, her smile was "crooked and yellow" due to the congenitally missing tooth number 10 and peg-shaped tooth number 8. The dentists' treatment plans for teeth color and form and the cosmetic services expenses were recorded. The treatment plans of the two areas were compared. ResultsFor dental form, most dentists' treatment plans were categorized as "No intervention" (privileged area: 37.5 %, less-privileged area: 56.53 %, and total: 46.80 %). The percentage of dentists in the privileged area who prescribed cosmetic services was twice that of the less-privileged area (33.33 % versus 17.39 %). The intervention for dental form varied from placing 1 unit of composite veneer to 10 units of ceramic laminates or orthodontics with a wide range of treatment costs ($42.09 to $1079.14). For tooth color, most dentists (privileged area: 62.50 %, less-privileged area: 30.43 %, and total: 46.80 %) were categorized as "Interventionists." For tooth color, the treatment plans varied from scaling and root planing, bleaching, and composite veneer with various costs ($7.19 to $197.84). ConclusionCosmetic treatment plans and expenses varied significantly for a single USP, with many not aligning with the standard treatment plan. Some dentists offered treatments even without a chief complaint from the patient. Dentists in privileged areas were twice as likely to prescribe cosmetic treatments compared to those in less privileged areas. Therefore, cosmetic services necessitate monitoring, establishing clear diagnostic criteria, and implementing educational interventions.

Evolution of tooth morphological complexity and its association with the position of tooth eruption in the jaw in non-mammalian synapsids.

Heterodonty and complex molar morphology are important characteristics of mammals acquired during the evolution of early mammals from non-mammalian synapsids. Some non-mammalian synapsids had only simple, unicuspid teeth, whereas others had complex, multicuspid teeth. In this study, we reconstructed the ancestral states of tooth morphological complexity across non-mammalian synapsids to show that morphologically complex teeth evolved independently multiple times within Therapsida and that secondary simplification of tooth morphology occurred in some non-mammalian Cynodontia. In some mammals, secondary evolution of simpler teeth from complex molars has been previously reported to correlate with an anterior shift of tooth eruption position in the jaw, as evaluated by the dentition position relative to the ends of component bones used as reference points in the upper jaw. Our phylogenetic comparative analyses showed a significant correlation between an increase in tooth complexity and a posterior shift in the dentition position relative to only one of the three specific ends of component bones that we used as reference points in the upper jaw of non-mammalian synapsids. The ends of component bones depend on the shape and relative area of each bone, which appear to vary considerably among the synapsid taxa. Quantification of the dentition position along the anteroposterior axis in the overall cranium showed suggestive evidence of a correlation between an increase in tooth complexity and a posterior shift in the dentition position among non-mammalian synapsids. This correlation supports the hypothesis that a posterior shift of tooth eruption position relative to the morphogenetic fields that determine tooth form have contributed to the evolution of morphologically complex teeth in non-mammalian synapsids, if the position in the cranium represents a certain point in the morphogenetic fields.

Robust optimization of hypoid gear contact performance considering tooth form error: Design sensitivity and Pareto front

Optimization of hypoid gear contact performance is challenging due to its nonconvex nature and the handling of non-linear constraints involving complex gear contact behavior. In addition, the contact performance in the existing optimization schemes is highly reliant on the manufacturing quality, for example, the uncertain tooth form errors induced by machining tolerances and blade wear are usually ignored. To tackle these problems, a robust optimization methodology is proposed for hypoid gear contact performance. A finite element/contact mechanics model is established, which considers the stochastic tooth form errors following a Gaussian distribution model. The non-linear constraints are incorporated to avoid edge contact under loaded conditions, and tooth surface interference due to error. This methodology guarantees the feasible solution space and reduces the optimization complexity by the independent identification model. The identification model of the optimal solution is flexible in the parameter selection while keeping tooth depth. This non-deterministic problem is optimized based on the pattern search method. The Pareto front and design sensitivity analysis demonstrate the effectiveness and robustness of the proposed optimization methodology.

An analytical approach for predicting the fillet and contact stresses in symmetric and asymmetric spur gears under frictional mesh assumptions

A precise estimation of the bending and contact stresses, as well as the true friction value during the gear mesh, are critical aspects of a cost-effective and safe gear design. Previous studies have usually neglected friction by assuming a frictionless contact. Additionally, the impact of friction on the bending stress of spur gears has rarely been addressed. Moreover, to the authors' best knowledge, the impact of friction on the weakest section, stress concentration factor, and Lewis form factor remain unexplored for both symmetric and asymmetric gears. This study presents an analytical model incorporating friction at different contact locations to calculate the variables related to the tooth's weakest section. This model facilitates the evaluation of the stress concentration factor, Lewis form factor, and maximum tensile stress for symmetric and asymmetric gears. The proposed model is especially beneficial for assessing the load-carrying capacity of spur gears operating in challenging conditions. The results showed that the asymmetric spur gear is superior to its equivalent symmetric counterpart in terms of tooth form factor; however, this superiority decreases as the coefficient of friction increases. In addition, friction has been found to have a greater effect on fillet stress than contact stress. For μ = 0.2, at the HPSTC, the contact load and tooth form factor decreased by 7 % and 12 %, respectively, and the fillet stress worsened by 13 % compared to the frictionless assumption. Meanwhile, at the LPSTC, the stress concentration factor and contact stress increased by 9 % and 3 %, respectively.

Intranasal Tooth in a Patient with Cleft Lip and Palate: Case Report

A rare form of ectopic teeth is the nasal tooth. This is a very rare clinical phenomenon. A clear etiology was not suspected in most of the reported cases. However, many etiologies have been identified, including maxillary osteomyelitis, dental trauma, nasal infections, development of defects such as cleft palate, and genetic factors. It can cause a variety of problems, like nasal obstruction, chronic rhinorrhea, and voice disturbances. Surgical removal of the tooth has been suggested as a treatment to reduce symptoms and prevent further complications.

Different approaches and type of anaesthesia required for the extraction of inverted mesiodens: A case series with review of literature

Supernumerary teeth are additional teeth or toothlike structures that have erupted or remained unerupted in addition to the 20 deciduous teeth and 32 permanent teeth. The size, form, and number of teeth can all vary. It is the most frequent type of supernumerary tooth, and it is generally found between the top two central incisors, which may be impacted or erupted. CBCT pictures were collected to properly diagnose the form and location of the mesiodens. Their presence can cause a range of clinical issues. The current report discusses a rare example of palatally positioned, inverted, and impacted mesiodens discovered during a malocclusion radiographic evaluation. It seeks to demonstrate early detection, planning, and the proper method, allowing the teeth and neighbouring teeth to be preserved.

Incident angle optimization with multiple conflicting objectives based on BP-MOPSO in oblique laser interferometry

The oblique incident phase-shifting interferometric measurement method is an effective technique for assessing gear tooth form deviation. In the measurement process, the tooth flank incident angle is a crucial factor determining the quality of interferograms. Addressing the challenge in traditional optical path design, where the selection of the tooth flank incident angle encounters a trade-off among quality features such as measurable tooth area (MTA), interference fringe density (IFD) and interferogram compression ratio (ICR), this paper proposes an optimized method for the tooth flank incident angle. Firstly, a comprehensive evaluation model is established to calculate and analyze the MTA, IFD and ICR of the helical gear. Secondly, by integrating BP neural network and Multi-Objective Particle Swarm Optimization (MOPSO) algorithm, a tooth flank incident angle optimization method is devised to simultaneously optimize the measurement light incident angle γ and the rotation angle of the gear axis β. Finally, simulation analyses and physical experiments are employed to demonstrate the feasibility of the proposed method, compared to before optimization, the pseudocorrelation (PSD) value has increased by an average of 34%, and the residual points have decreased by an average of 80%, confirming its capability to improve quality interferogram and measurement accuracy.

First report in the fossil record of a shark tooth embedded in a pinniped bone

There are now many examples in the fossil record of shark bite marks preserved on biogenic materials including coprolites, ammonoids, sea star ossicles, an echinoid, and bone and calcified cartilage. These exceptional fossils document evidence of exploratory behavior, active predation, and/or scavenging. However, only a small subset report on the presence of shark teeth embedded in fossilized bone or cartilage. Although a few shark tooth-marked seal bones are known from the fossil record, no direct evidence of predation or scavenging in the form of a shark tooth embedded in a fossil seal bone has yet been documented. Herein, we describe the first shark tooth embedded in a seal (Phocidae Gray, 1821) bone, a calcaneum (CMM-V-6964), that was surface collected in Mosaic’s South Fort Meade Mine, Hardee County, Fort Meade, Florida, United States. The isolated bone originated from within the Bone Valley Member of the Peace River Formation (Hawthorn Group). The partial tooth is identified as having come from an Early Pliocene great white shark, Carcharodon carcharias (Linnaeus, 1758). This discovery also represents the first C. carcharias tooth ever found embedded in a fossil bone. The embedded tooth may have come about as a result of active predation or scavenging. The extant macropredatory sharks, Carcharodon carcharias (great white shark), Notorynchus cepedianus (Péron, 1807) (sevengill shark), Somniosus microcephalus (Bloch & Schneider, 1801) (the Greenland shark), and Somniosus antarcticus Whitley, 1939 (sleeper shark), are known to actively prey upon seals (Pinnipedia Illiger, 1811). If this peculiar fossil association resulted from active predation, the seal did not survive the encounter because there is no evidence of healing in the area around the embedded shark tooth.

Molecular Evidence for Relaxed Selection on the Enamel Genes of Toothed Whales (Odontoceti) with Degenerative Enamel Phenotypes.

Different species of toothed whales (Odontoceti) exhibit a variety of tooth forms and enamel types. Some odontocetes have highly prismatic enamel with Hunter-Schreger bands, whereas enamel is vestigial or entirely lacking in other species. Different tooth forms and enamel types are associated with alternate feeding strategies that range from biting and grasping prey with teeth in most oceanic and river dolphins to the suction feeding of softer prey items without the use of teeth in many beaked whales. At the molecular level, previous studies have documented inactivating mutations in the enamel-specific genes of some odontocete species that lack complex enamel. At a broader scale, however, it is unclear whether enamel complexity across the full diversity of extant Odontoceti correlates with the relative strength of purifying selection on enamel-specific genes. Here, we employ sequence alignments for seven enamel-specific genes (ACP4, AMBN, AMELX, AMTN, ENAM, KLK4, MMP20) in 62 odontocete species that are representative of all extant families. The sequences for 33 odontocete species were obtained from databases, and sequences for the remaining 29 species were newly generated for this study. We screened these alignments for inactivating mutations (e.g., frameshift indels) and provide a comprehensive catalog of these mutations in species with one or more inactivated enamel genes. Inactivating mutations are rare in Delphinidae (oceanic dolphins) and Platanistidae/Inioidea (river dolphins) that have higher enamel complexity scores. By contrast, mutations are much more numerous in clades such as Monodontidae (narwhal, beluga), Ziphiidae (beaked whales), Physeteroidea (sperm whales), and Phocoenidae (porpoises) that are characterized by simpler enamel or even enamelless teeth. Further, several higher-level taxa (e.g., Hyperoodon, Kogiidae, Monodontidae) possess shared inactivating mutations in one or more enamel genes, which suggests loss of function of these genes in the common ancestor of each clade. We also performed selection (dN/dS) analyses on a concatenation of these genes and used linear regression and Spearman's rank-order correlation to test for correlations between enamel complexity and two different measures of selection intensity (# of inactivating mutations per million years, dN/dS values). Selection analyses revealed that relaxed purifying selection is especially prominent in physeteroids, monodontids, and phocoenids. Linear regressions and correlation analyses revealed a strong negative correlation between selective pressure (dN/dS values) and enamel complexity. Stronger purifying selection (low dN/dS) is found on branches with more complex enamel and weaker purifying selection (higher dN/dS) occurs on branches with less complex enamel or enamelless teeth. As odontocetes diversified into a variety of feeding modes, in particular, the suction capture of prey, a reduced reliance on the dentition for prey capture resulted in the relaxed selection of genes that are critical to enamel development.

Orthodontic management of midline diastema caused by mesiodens: A case series

Supernumerary teeth are teeth in excess of the normal number, found in both primary and permanent dentition. Mesiodens are the most common form of supernumerary teeth, usually found in the maxillary anterior region, in between the permanent central incisors. It may lead to complications such as malocclusion, unesthetic appearance, food lodgment, and cyst formation. Early diagnosis and immediate intervention are advised to avoid orthodontic and pathological complications. The case series here discusses three different cases for presence of supernumerary teeth leading to development of midline diastema. Extraction of the supernumerary teeth followed by fixed orthodontic treatment was performed to correct the malocclusion and improve the facial esthetics.

Dental Dynamics: A Fast New Tool for Quantifying Tooth and Jaw Biomechanics in 3D Slicer.

Teeth reveal how organisms interact with their environment. Biologists have long looked at the diverse form and function of teeth to study the evolution of feeding, fighting, and development. The exponential rise in the quantity and accessibility of computed tomography (CT) data has enabled morphologists to study teeth at finer resolutions and larger macroevolutionary scales. Measuring tooth function is no easy task, in fact, much of our mechanical understanding is derived from dental shape. Categorical descriptors of tooth shape such as morphological homodonty and heterodonty, overlook nuances in function by reducing tooth diversity for comparative analysis. The functional homodonty method quantitatively assesses the functional diversity of whole dentitions from tooth shape. This method uses tooth surface area and position to calculate the transmission of stress and estimates a threshold for functionally homodont teeth through bootstrapping and clustering techniques. However, some vertebrates have hundreds or thousands of teeth and measuring the shape and function of every individual tooth can be a painstaking task. Here, we present Dental Dynamics, a module for 3D Slicer that allows for the fast and precise quantification of dentitions and jaws. The tool automates the calculation of several tooth traits classically used to describe form and function (i.e., aspect ratio, mechanical advantage, force, etc.). To demonstrate the usefulness of our module we used Dental Dynamics to quantify 780 teeth across 20 salamanders that exhibit diverse ecologies. We coupled these data with the functional homodonty method to investigate the hypothesis that arboreal Aneides salamanders have novel tooth functions. Dental Dynamics provides a new and fast way to measure teeth and increases the accessibility of the functional homodonty method. We hope Dental Dynamics will encourage further theoretical and methodological development for quantifying and studying teeth.

Immature tooth with the coexistence of dilaceration and radicular dens invaginatus

Abstract Trauma to the developing permanent successors leads to alteration in form, size, structure, and quantity of teeth. Management of teeth with such morphological complexity becomes challenging. The severity of the anomaly decides the treatment planning. A case of coexistence of radicular dens invaginatus and dilaceration is reported, which was to be managed surgically due to uneventful endodontic attempts and complicated root anatomy.

Rehabilitation of Worn Anterior Teeth with Ceramic Veneers

Abstract The use of porcelain laminate veneers to solve esthetic and functional problems has proven to be a valid management option, especially in the anterior esthetic zone. Veneers are a reliable treatment option to modify the appearance of tooth position and form, to close diastema or cervical embrasures, or to change the tooth shade. Porcelain veneers are one of the best corrective options available considering biological, functional, mechanical, and esthetic points of view.

The Effect of Diabetes on Implanted Dentures, A Systematic Review

Background: Dentures are removably inserted dental prosthetics that fill up tooth gaps. There are many types of dentures, including complete, partial and implant-supported dentures. As long-term supports for tooth replacements, dental implants have significantly changed the treatment philosophies of conventional prosthodontics. However, the success and durability of these prosthetic devices may be impacted if a person seeking denture implants has diabetes. Diabetes affects the body in many ways, including the mouth's oral health. Immediate dentures have many benefits, including better oral functions, preservation of lower facial height, preservation of tooth sockets, improvement of aesthetics, and replication of natural teeth's shape, form, and location by artificial teeth. Diabetes mellitus has been reported to be associated strongly with the oral health. The higher glucose microenvironment prolongs healing of tooth extraction sockets. Thus, encouraging the healing of tooth extraction sockets is crucial from a therapeutic perspective for people with diabetes mellitus. Methods: An electronic search of English peer-reviewed dental literature on PubMed, Science Direct and Google Scholar was conducted to identify all publications reporting on how diabetes affect dentures until August 2023. Overall, 977 publications were found through an electronic and manual search, out of which 130 articles were selected after screening based on title and abstract. A total of 52 publications passed the second review phase after assessment for eligibility, from which 24 studies were excluded after full-text screening. Finally, a total of 28 studies were selected. A total of 10 articles were found to match our eligibility criteria to the full and were included in the final systematic review. Conclusion: Diabetes negatively impacts implanted dentures' success and longevity, leading to complications like Candida infection, poor bone integration, peri-implantitis, and compromised healing. Larger clinical trials are needed to understand diabetes's impact on implant therapy outcomes. Clinicians should assess patients' overall health, monitor glycemic control, maintain oral hygiene, and perform regular maintenance for optimal outcomes.

Dental and temporomandibular joint pathology of the red fox (Vulpes vulpes)

Skulls from 305 red foxes (Vulpes vulpes) were examined using predefined criteria to assess for the presence and severity of dental and temporomandibular joint (TMJ) pathology. Of the 305 specimens examined, 131 were male (42.9%), 103 were female (33.4%), 71 were of unknown sex (23.3%), 238 were adults (78.03%) and 67 were young adults (21.97%), with juveniles excluded from the study. Of a maximum of 12,810 possible teeth, 12,355 (96.5%) were present for examination, 72 (0.6%) were absent congenitally, 97 (0.8%) were acquired tooth loss and 280 (2.2%) were absent artefactually. Eight teeth (0.06%) in five specimens (1.6%) had abnormal tooth form and four (0.03%) supernumerary teeth were present across four (1.3%) specimens. Ten persistent deciduous teeth were present in seven (2.3%) specimens and six (0.05%) unerupted teeth were found in four (1.1%) specimens. Root number variation was present in 51 (0.4%) teeth, predominantly premolar teeth. Twenty-one (6.9%) specimens had lesions consistent with enamel hypoplasia and 42 (13.8%) showed root fenestrations in the maxillary alveolar bone. Periodontitis and attrition/abrasion were present in most specimens (56.7% and 96.1%, respectively). Three-hundred and eighty (3.1%) teeth were fractured, with the most common fracture type being root fractures. Eleven periapical lesions were found in nine (0.03%) specimens. Six-hundred and eight TMJs were evaluated and many specimens (11.5%) had evidence of low-grade TMJ osteoarthritis. Overall, these red foxes share similar dental pathology to other foxes, but had a higher prevalence of congenital tooth absence, persistent deciduous teeth, TMJ pathology and enamel hypoplasia.

Posterior restoration rotational torque associated with cuspal incline angulation: A proof of concept

Off-axis, external forces with a moment arm on posterior restorations have not been investigated in experimental studies. The purpose of this proof-of-concept study was to determine the interaction between occlusal force directed toward cuspal incline angulations with variations in base width and preparation vertical heights. Torque forces on a single crown restoration in simulated premolar and molar tooth forms were calculated for 3 different rotational axes. Trigonometric calculations were made to determine the amount of torque generated in a simulated-crown restoration in premolar and molar tooth forms. Restorations with different cuspal incline angulations were loaded with an off-axis force of 200N. This force was applied to 5 different cuspal incline angulations in both tooth forms at varying preparation heights. Right triangles were used to enable trigonometric computations of the resulting moment arms that accompanied the 3 rotational axes. The total torque values were calculated with a range from 7.5 to 372.8 Ncm. The highest levels of torque were generated in the 5-mm-high molar tooth form with a rotational axis located within the root form, perpendicular to the 45-degree cuspal incline. In general, large moment arms were generated with steep cuspal incline angulations and mid-root axis locations; the lowest torque values in all cuspal incline angulations were found in the rotational axis locations at the crown finish line. The torque values at the rotational axis finish line location were found to be greatest in the largest vertical tooth form height category (5mm) in both tooth model sizes. The crown restoration cuspal incline angulations, vertical preparation heights, base widths, and rotational axis locations all played a role in the torque force levels generated, probably influencing restoration stability.

Food texture and vitamin D influence mouse mandible form and molar roots.

Industrialization influenced several facets of lifestyle, including softer nutrient-poor diets that contributed to vitamin D deficiency in post-industrzialized populations, with concomitantly increased dental problems. Here we simulated a post-industrialized diet in a mouse model to test the effects of diet texture and vitamin D level on mandible and third molar (M3) forms. Mice were raised on a soft diet with vitamin D (VitD) or without it (NoD), or on a hard diet with vitamin D. We hypothesized that a VitD/hard diet is optimal for normal mandible and tooth root form, as well as for timely M3 initiation. Subsets of adult NoD/soft and VitD/soft groups were bred to produce embryos that were micro-computed tomography (μCT) scanned to stage M3 development. M3 stage did not differ between embryos from mothers fed VitD and NoD diets, indicating that vitamin D does not affect timing of M3 onset. Sacrificed adult mice were μCT-scanned, their mandibles 3D-landmarked and M3 roots were measured. Principal component (PC) analysis described the largest proportion of mandible shape variance (PC1, 30.1%) related to diet texture, and nominal shape variance (PC2, 13.8%) related to vitamin D. Mice fed a soft diet had shorter, relatively narrower, and somewhat differently shaped mandibles that recapitulated findings in human populations. ANOVA and other multivariate tests found significantly wider M3 roots and larger root canals in mice fed a soft diet, with vitamin D having little effect. Altogether our experiments using a mouse model contribute new insights about how a post-industrial diet may influence human craniodental variation.

Pemberdayaan Guru dan Orang Tua tentang Penanganan Kegawatdaruratan Rongga Mulut Anak Pra Sekolah

Oral emergencies are trauma involving the teeth and the supporting structures of the teeth. This trauma can be in the form of open wounds, broken teeth and loose teeth. During the COVID-19 pandemic, mothers had more time to spend with their children, so they were expected to be able to provide quick and appropriate action if their children experienced trauma to their teeth. This empowerment activity aims to increase knowledge and skills in handling oral emergencies. This Community Service activity was carried out by the Trisakti University Faculty of Dentistry Team for Teachers and Parents of Kindergarten Al Hidayah 2 Kelapa Gading on December 1, 2022. Counseling and training were carried out offline using presentations on open wounds, broken teeth loose teeth, and first aid that can be done at home. Training and counseling was carried out to 46 participants for 60 minutes. Participants' knowledge was assessed by pre-test and post-test using Google Form. From the results obtained, it was seen that there was an increase in the knowledge of the counseling participants by 13.5% (mean pre-test score was 28.9 ± 14.6 and mean post-test score was 68 ± 15.3).

Comparison of pleasant and unpleasant smile characteristics in the perception of the laypeople in an Iranian population

This study aimed to compare the characteristics of pleasant and unpleasant smiles from the perception of laypeople. Two-hundred posed smile photographs were obtained from adult participants with no anomaly, restoration, or severe crowding and spacing in anterior teeth. Photographs were shown to 26 judges to give each photograph a score for attractiveness. Upper and lower quartiles for the most and least rated smiles were determined, and variables including gingival display, smile arc, midline deviation, buccal corridor, smile width, tooth rotation or malposition, diastema, upper and lower vermilion show, and tooth form were measured. Independent-sample t test and Pearson chi-square analysis were used to determine the differences between the pleasant and unpleasant groups for quantitative and qualitative variables, respectively. The linear regression model revealed variables with the most significant impact on the mean score. All quantitative and qualitative variables except tooth form significantly differed between pleasant and unpleasant smile groups (P<0.05). The consonant smile arc was associated with an increase of 12.59% in mean scores compared with the inconsonant smile arc. Each tooth reported with malposition was correlated with a decrease of 9.37% in the scores. In the same way, each 1-mm increase in midline diastema and occlusal cant coincided with a drop of 8.73% and 3.59% in scores, respectively. The results of this study suggested that smile arc, tooth malposition, midline diastema, and occlusal plane canting had the most impact on smile esthetics and should be given priority by orthodontists in the treatment plan of choice.