Complete Tooth Research Articles

Cognitive Decline and Oral Health in Middle-aged Adults in the ARIC Study

Even before dementia becomes apparent, cognitive decline may contribute to deterioration in oral health. This cohort study of middle-aged adults evaluated associations of six-year change in cognitive function with oral health behaviors and conditions in the Atherosclerosis Risk in Communities (ARIC) study. Cognitive function was measured at study visits in 1990-1992 and 1996-1998 with three tests: (a) Delayed Word Recall (DWR), (b) Digit Symbol Substitution (DSS), and (c) Word Fluency (WF). Cognitive decline scores were computed as ‘studentized’ residuals of 1996-1998 scores regressed against 1990-1992 scores. In 1996-1998, 10,050 participants answered dental screening questions, and 5,878 of 8,782 dentate participants received a comprehensive oral examination. Multiple regression models used cognitive change to predict oral health behaviors and conditions with adjustment for covariates. In the fully adjusted models, greater decline in all three measures of cognitive function was associated with increased odds of complete tooth loss. Greater decline in DSS and WF scores was associated with infrequent toothbrushing. Decline in WF scores was also associated with higher plaque levels. In these middle-aged adults, six-year cognitive decline was modestly associated with less frequent toothbrushing, plaque deposit, and greater odds of edentulism, but not with other oral behaviors or diseases.

Trends of Edentulism Among Middle-Aged and Older Asian Americans

We estimated national trends of the prevalence of edentulism (complete tooth loss) for Asian American subgroups in the United States and investigated factors that could contribute to improvements in edentulism across populations over time. We used 10 waves of the National Health Interview Survey data collected from 1999 to 2008. Eligible respondents were those aged 50 years and older who completed the question on tooth loss. We contrasted the odds and probabilities of edentulism over time in Chinese, Filipinos, Asian Indians, and other Asians with those in Whites, Blacks, and Hispanics. The rates of edentulism differed substantially across Asian subgroups. Compared with Whites, Chinese and other Asians had a lower risk of being edentulous, whereas being Filipino increased the odds. The rate for Asian Indians was similar to that for Whites. Nonetheless, rates of decline were similar across the Asian population groups. Asian Americans are heterogeneous in edentulism. Innovative and sustainable public health programs and services are essential to prevent oral health diseases and conditions.

SAT0089 The impact of periodontal disease on early inflammatory arthritis persists even after all teeth are lost

BackgroundData suggests that individuals with periodontal disease (PD) may be more likely to develop rheumatoid arthritis (RA) and have worse disease activity. PD is a common inflammatory disease characterized by...

OP032: What can fibula flap do in jaw reconstruction?

Part A 3-D model simulation and reconstruction of composite total maxillectomy defects with fibula osteomyocutaneous flap flow-through from radial forearm flap 3-Dimensional model simulation technique and free fibula osteomyocutaneous flap flow-through from radial forearm flap were used to reconstruct a total maxillectomy defect for a 21-years-old female patient. Preoperatively, the 3-dimensional simulated resin models of skeleton and fibula were used to design. In surgery, a 22-cm length free fibula was divided into four segments to make skeletal framework as surgical planning with a radial forearm flap flow-through for the free fibula flap with the skin paddle to repair the palatal and nasal region. Free fibula and radial forearm flap were alive, and the patient was satisfied with the results both aesthetically and functionally due to dental rehabilitation which was carried out 6 months postoperatively. This preliminarily clinical study and case demonstrated the fibula osteomyocutaneous flap is an ideal donor site in total maxillectomy defect reconstruction; the flow-through forearm radial flap not only serves as the vascular bridge to midface reconstruction, but also provides sufficient soft tissue cover for the intra-oral defect. Part B Double barrel fibula free flap with second-staged dental implants for mandibular reconstruction. The aim of this study was to evaluate the method for segmental mandibular reconstruction using double-barrel fibular flap with second-staged dental implant-supported prosthetic rehabilitation. 5 patients (2 gingival carcinomas, 2 ameloblastomas and 1 keratocyst) had undergone segmental mandibulectomy with 6–9 cm defect length. After tumor resection, double barrel fibula osteomyocutaneous flaps were used to reconstruct the mandible. All the flaps were alive with no complications post-operatively. Follow-up at 6 months showed good osteo-integration in panoramic radiograph and esthetic facial appearance. The patients underwent second-stage implants 8 months after fibula transplantation and implant-supported prosthesis was installed 1–2 months later to complete teeth rehabilitation.

Mammal-like tooth from the Upper Triassic of Poland

Recent Triassic discoveries have extended the record of near-mammals (Mammaliaformes) back to the Norian, about 215 Ma, and reveal a significant diversity of Late Triassic (Norian-Rhaetian) forms. We now add to this Late Triassic diversity a nearly complete double-rooted right lower molariform tooth (ZPAL V.33/734) from the Polish Upper Triassic that is significant because it comes from uppermost Norian–lower Rhaetian rocks and is the first discovery of a mammal-like tooth in the Mesozoic of Poland. The described tooth shows transitional dental morphology between advanced cynodonts and mammaliaforms and it appears to represent a basal mammaliaform (genus Hallautherium), probably belonging to Morganucodonta.

二段充てん法による内はすば歯車の成形

In a previous paper, we proposed a two-step cold extrusion method of shaping external spur gears and helical gears. In the present paper, we describe how this filling method is applied to the shaping of internal helical gears. A specially designed mandrel for an internal helical gear utilizing the two-step filling method was used to expand and the inner diameter of the cylindrical workpiece. The specifications of these gears are as follows: module m=1.0, 1.25 and 1.5 mm; helix angle ß=20 deg; number of teeth Z=12-15 and whole depth h=2.00 module. The materials used were aluminum A1200 and low carbon steel S15C. The criterion for shaping complete teeth is discussed primarily in terms of punch pressure and the reduction in the area and the expansion ratio of the inner diameter of the workpiece. The approach that we described here successfully produced a filled up internal helical gear with only a few percent reduction in area. The punch pressure was very low, far below the strength of the punch material.

Molecular factors resulting in tooth agenesis and contemporary approaches for regeneration: A review

This review discusses the complex epithelial-mesenchymal interactions that occur during tooth development and systemic anomalies that may result in hypodontia. Emphasis is placed on four interacting signaling families (Shh, FGF, BMP, and Wnt) that have been identified for their integral role in complete tooth development and on several genetic mutations in the MSX1, PAX9, EDA, and AXIN2 genes that arrest tooth development. Proposed treatment options are presented, including signaling factor supplementation and stem cell isolation for bioengineering new teeth.

The Assessment of Speech Quality and Intellibility After Replacement of Lost Teeth With Removable Dentures: Review of Literature

Summary The prevalence of edentulism among Latvian population is high. According to the World Health Organization criteria complete tooth loss is regarded as a disability. One of the basic oral cavity functions is taking part in speech production. Alterations in oral cavity, caused by tooth loss and resorption of its supporting alveolar ridge, can produce changes in speech quality and intelligibility. This can lead to psychological and social problems, thus decreasing the patient’s quality of life. There are several options in replacing missing teeth. In Latvia prosthetic rehabilitation with removable dentures is in great demand. It is mentioned in literature, that removable dentures improve speech quality and intelligibility. However, there is no consensus in this field. The objective of this review is to screen literature for data related to the assessment of speech quality and intelligibility after replacement of lost teeth with removable dentures. Literature was selected through several electronic databases, as well as a manual search in dental journals. The detailed analysis of thirty two articles was performed and some significant facts were revealed. There exists an opinion, that removable dentures may have a negative effect on speech production. As the volume of oral cavity is diminished, resonation of oral cavity is decreased. Artificial teeth, removable denture base can limit tongue space and change the location of its articulation contacts. The assessment of speech quality and intelligibility is an essential diagnostic tool before and after prosthetic rehabilitation in order to provide the best option for restoring lost function. A standardized method for determining changes in speech quality after tooth loss and further prosthodontics has not yet been established. Semi-standardized instruments for the analysis of speech disorders are well documented when dealing with speech changes before and after prosthetic rehabilitation with various oral osseointegrated implant supported prostheses. For the Latvian language this method has not been described yet.

The global burden of periodontal disease: towards integration with chronic disease prevention and control

Chronic diseases are accelerating globally, advancing across all regions and pervading all socioeconomic classes. Unhealthy diet and poor nutrition, physical inactivity, tobacco use, excessive use of alcohol and psychosocial stress are the most important risk factors. Periodontal disease is a component of the global burden of chronic disease, and chronic disease and periodontal disease have the same essential risk factors. In addition, severe periodontal disease is related to poor oral hygiene and to poor general health (e.g. the presence of diabetes mellitus and other systemic diseases). The present report highlights the global burden of periodontal disease: the ultimate burden of periodontal disease (tooth loss), as well as signs of periodontal disease, are described from World Health Organization (WHO) epidemiological data. High prevalence rates of complete tooth loss are found in upper middle-income countries, whereas the tooth-loss rates, at the time of writing, are modest for low-income countries. In high-income countries somewhat lower rates for edentulism are found when compared with upper middle-income countries. Around the world, social inequality in tooth loss is profound within countries. The Community Periodontal Index was introduced by the WHO in 1987 for countries to produce periodontal health profiles and to assist countries in the planning and evaluation of intervention programs. Globally, gingival bleeding is the most prevalent sign of disease, whereas the presence of deep periodontal pockets (≥6 mm) varies from 10% to 15% in adult populations. Intercountry and intracountry variations are found in the prevalence of periodontal disease, and these variations relate to socio-environmental conditions, behavioral risk factors, general health status of people (e.g. diabetes and HIV status) and oral health systems. National public health initiatives for the control and prevention of periodontal disease should include oral health promotion and integrated disease-prevention strategies based on common risk-factor approaches. Capacity building of oral health systems must consider the establishment of a financially fair service in periodontal care. Health systems research is needed for the evaluation of population-oriented oral health programs.

Avulsed maxillary central incisors: The case for autotransplantation

A Traumatic dental injuries most often occur in childhood and early adolescence. The most serious of these injuries is complete tooth avulsion. The incidence of avulsion is greatest for the maxillary central incisors and usually occurs when they are erupting between the ages of 7 and 10 years. A critical decision for the dentist at this time is whether to replant the avulsed tooth. There are many biologic considerations with varying outcomes. At the time of the injury, it is often a difficult conversation to have with the parents. Also, since these types of injuries

A novel approach for a complete 3D tooth reconstruction using only 3D crown data

Current methods to produce 3-dimensional complete tooth (enamel, dentin and pulp) models involve conversion from tomographic data. In the paper a novel approach to obtain the complete 3D reconstruction of a tooth starting from the only 3D crown information is described. Using as reference models, five human posterior molars derived from micro-computed tomography (CT) data, specific computer aided design (CAD) modeling procedures were developed to create, in a simplified way, the surfaces of enamel, dentin and pulp of the teeth, starting from the data of a molar acquired by a non-contact reverse engineering (RE) system. To evaluate the simplified model, finite element method (FEM) simulations were performed and compared. The results from FEM analysis confirm the general validity of the proposed approach. This method allows to generate an efficient complete 3D reconstruction of teeth with a good approximation of the shape, due to the small number of parameters to adjust, and requires little interaction from the user. The described method can be successfully adopted to generate detailed 3D CAD models of teeth starting only from the crown data, acquired by non-contact RE systems (structured-light scanners, laser scanners or intra-oral laser scanners). It could be quickly implemented for other dental or biomechanical applications without the use of more expensive CT and micro-CT.

Wearing of complete dentures reduces slow fibre and enhances hybrid fibre fraction in masseter muscle

Edentulous conditions and use of complete dentures alter the function of jaw muscles, which is presumably reflected in the myosin heavy chain (MyHC) isoform composition. This study is the first dealing with MyHC isoforms expression in edentulous persons with the aim to clarify to which extent the decreased functional load following teeth loss contributes to the changed muscle phenotype during ageing. We analysed MyHC expression in old masseter muscle at decreased and full functional load by comparing age-matched edentulous and dentate subjects. Edentulous subjects had upper and lower complete dentures. Dentate subjects had at least 24 natural teeth in continuous dental arches with two molars present in each quadrant and normal intermaxillary relationship. The adaptive response to the reduced masticatory load was lower numerical and area proportion of MyHC-1 expressing fibres and higher numerical proportion of hybrid fibres in edentulous compared with dentate subjects with no significant difference in the proportion of MyHC-neo-expressing fibres between both groups. We conclude that the observed differences in the proportion of fibre types between denture wearers and dentate subjects cannot be ascribed to degenerative changes intrinsic to the ageing muscle, but to functional differences in muscle activity and to morphological alterations of stomatognathic system accompanying the complete teeth loss.

Engineering of dental tissues; reality or distant prospect

Tissue engineering envelops a fast developing multidisciplinary field. Both from a medical and dental social point of view, there is great need to safeguard tissues and organs to overcome the shortage of donor organs and to reduce the health care cost. The ability to replace malfunctioning body parts has long been an issue of fiction and vision throughout the development of medical practice. One of the most striking examples is the legend of St. Cosmas and St. Damien, which describes the replacement of a man’s gangrenous leg with the limb of a dead black man. Apart from this legendary example, the more realistic replacement of damaged body tissue started in dentistry. The French surgeon Ambroise Pare (1510–1590) described the replacement of missing teeth by donor teeth, which were taken form “serfs”. It goes without saying that this kind of early transplantation was prone to failure due to existing lack of knowledge about immunology and sterility as well as the underlying phenomena of wound healing. The discovery of the sterility principles meant an enormous step forward. However, especially, all recent progress, as made in the field of molecular sciences as well as biomaterials and chemical engineering, seem to make the original dream of complete tissue and organ replacement reality. The question is whether this suggestion is indeed true which advantages and disadvantages are associated with this technique and what the final use of tissue engineering will be for the general practitioner. Tissue engineering can best be described as the creation of tissue. Tissue engineering is based on the tissue engineering paradigm, i.e. scaffold materials (a biomaterial in the shape of the newly to be regenerated tissue), stem cells (primordial cells which possess the potency to differentiate and proliferate in all kinds of different tissues), and signaling molecules (growth factors responsible for the differentiation of stem cells). In principle, tissue engineering can be applied for each existing tissue defect. At the moment, bone, periodontal ligament, gingiva and a complete tooth are important applications for dental tissue engineering.

Tooth loss and edentulism in the Turkish elderly

The aim of this study was to evaluate partial and complete tooth loss and some related demographic factors, and oral health behaviors among Turkish elderly. According to recent censuses, elderly population of Turkey is rapidly growing. There is no nationwide information related to edentulism and natural teeth retention among 65–74 year-old people in Turkey. In this nationwide representative cross-sectional study, 1545 subjects aged 65–74 years were evaluated using the proportional stratified cluster sampling method. The data were collected via a structured, pre-tested face to face administered questionnaire and an oral examination. Chi-square test and binary logistic regression analyses were used to determine the significance of explanatory variables. 48.0% of elderly were edentate. The mean DMF-T was 25.8±8.5. These values were higher in women (p=0.016), older age (p<0.001) and rural individuals (p<0.001). Only 12.4% of the subjects had functional dentition. Age, visiting dentist, and health security were associated with edentulism. Female sex (OR=1.37), 70–74 age group (OR=2.08) and illiteracy (OR=3.25) were the independent factors of not having functional dentition. A reduction in edentulism in elderly may be achieved by the implementation of community programs promoting oral health for the prevention and treatment.

Genetic evidence for the vital function of osterix in cementogenesis

To date, attempts to regenerate a complete tooth, including the critical periodontal tissues associated with the tooth root, have not been successful. Controversy still exists regarding the origin of the cell source for cellular cementum (epithelial or mesenchymal). This disagreement may be partially due to a lack of understanding of the events leading to the initiation and development of the tooth roots and supportive tissues, such as the cementum. Osterix (OSX) is a transcriptional factor essential for osteogenesis, but its role in cementogenesis has not been addressed. In the present study, we first documented a close relationship between the temporal- and spatial-expression pattern of Osx and the formation of cellular cementum. We then generated 3.6-kilobase (kb) collagen type I (3.6-kb Col 1)-Osx transgenic mice, which displayed accelerated cementum formation versus wild-type (WT) controls. Importantly, the conditional deletion of Osx in the mesenchymal cells with two different Cre systems (the 2.3-kb Col 1 and an inducible CAG-Cre estrogen receptor [CreER]) led to a sharp reduction in cellular cementum formation (including the cementum mass and mineral deposition rate) and gene expression of dentin matrix protein 1 (DMP1) by cementocytes. However, the deletion of the Osx gene after cellular cementum formed did not alter the properties of the mature cementum as evaluated by backscattered scanning electron microscopy (SEM) and resin-casted SEM. Transient transfection of Osx in the cementoblasts in vitro significantly inhibited cell proliferation and increased cell differentiation and mineralization. Taken together, these data support: (1) the mesenchymal origin of cellular cementum (from periodontal ligament [PDL] progenitor cells); (2) the vital role of OSX in controlling the formation of cellular cementum; and (3) the limited remodeling of cellular cementum in adult mice.

Restoring physiological cell heterogeneity in the mesenchyme during tooth engineering

Tooth development is controlled by reciprocal epithelial-mesenchymal interactions. Complete teeth can form when culturing and implanting re-associations between single embryonic dental epithelial and mesenchymal cells. Although epithelial histogenesis is clear, very little is known about cell diversity and patterning in the mesenchyme. The aim of this work was to compare the situation in engineered and developing teeth at similar developmental stages. To this end, the expression of cell surface markers in the mesenchyme was investigated by immunostaining in: 1) embryonic mouse molars at embryonic day 14, as the initial cell source for re-associations, 2) cultured cell re-associations just before their implantation and 3) cultured cell re-associations implanted for two weeks. Surface markers allowed visualization of the complex patterning of different cell types and the differential timing in their appearance. The phenotype of mesenchymal cells rapidly changed when they were grown as a monolayer, even without passage. This might explain the rapid loss of their potential to sustain tooth formation after re-association. Except for markers associated with vascularization, which is not maintained in vitro, the staining pattern in the mesenchyme of cultured re-associations was similar to that observed in situ. After implantation, vascularization and the cellular heterogeneity in the mesenchyme were similar to what was observed in developing molars. Besides tissue oxygenation and its role in mineralization of dental matrices, vascularization is involved in the progressive increase in mesenchymal cell heterogeneity, by allowing external cells to enter the mesenchyme.

内径拡張を伴う外歯車の押出し成形

The shaping of spur gears by cold extrusion through the expansion of the inner diameter of a workpiece is examined experimentally. A workpiece is set with its inner diameter in the front part of a stepped mandrel, which is placed in a container. Then, it is extruded with the expansion of its inner diameter, by passing through the tooth part of the die. The specifications of gear examined are as follows: module m=1.25-2.0 mm, pressure angle 20 deg, number of teeth Z=18-16, and whole depth h=2.25 module. The material used is the low-carbon steel, JIS S15C. The criterion for the shaping of complete teeth is discussed in terms of reduction in area, expansion ratio of the inner diameter of the workpiece and other factors. This method can produce spur gears of much better shape, i.e. having complete teeth, than the former proposed extrusion method, without reducing the outer diameter of the workpiece. Especially, a gear having a relatively medium-to-large sized bore can also be well shaped by the present method. The needed pressure of the punch, mandrel, and die is far below the strength of the punch and die materials.

Prevalence of temporomandibular disorders in a population of complete denture wearers

Complete tooth loss among the elderly is still frequent in developing countries and the incidence of temporomandibular disorders (TMD) is a common finding in complete denture wearers. The aim of this study was to evaluate the prevalence of temporomandibular disorders (TMD) in a population of complete denture wearers. The data were collected by four examiners for the diagnosis of use and need for complete dentures followed by the World Health Organization standards and interviews for TMD signs and symptoms evaluation. Exploratory variables included demographic, socio-economic status and TMD prevalence. The prevalence of TMD among denture wearers was 55.12%. Chi-squared test showed no statistical difference between subjects with or without TMD for gender, geographical location and skin colour (p < 0.05). The number of subjects with TMD increased as the period of complete denture wear increased, although no statistical difference between groups were found (p < 0.05). There is a need of educational programmes aiming at the importance of health care and periodical change of a complete denture, and strategies with a preventive approach to quality general dental care.

Fibrin glue mixed with platelet-rich fibrin as a scaffold seeded with dental bud cells for tooth regeneration

Odontogenesis is a complex process with a series of epithelial-mesenchymal interactions and odontogenic molecular cascades. In tissue engineering of teeth from stem cells, platelet-rich fibrin (PRF), which is rich in growth factors and cytokines, may improve regeneration. Accordingly, PRF was added into fibrin glue to enrich the microenvironment with growth factors. Unerupted second molar tooth buds were harvested from miniature swine and cultured in vitro for 3 weeks to obtain dental bud cells (DBCs). Whole blood was collected for the preparation of PRF and fibrin glue before surgery. DBCs were suspended in fibrin glue and then enclosed with PRF, and the DBC-fibrin glue-PRF composite was autografted back into the original alveolar sockets. Radiographic and histological examinations were used to identify the regenerated tooth structure 36 weeks after implantation. Immunohistochemical staining was used to detect proteins specific to tooth regeneration. One pig developed a complete tooth with crown, root, pulp, enamel, dentin, odontoblast, cementum, blood vessels, and periodontal ligaments in indiscriminate shape. Another animal had an unerupted tooth that expressed cytokeratin 14, dentin matrix protein-1, vascular endothelial growth factor, and osteopontin. This study demonstrated, using autogenic cell transplantation in a porcine model, that DBCs seeded into fibrin glue-PRF could regenerate a complete tooth.

Research on the 3D Modeling Method of Epicycloids’ Bevel Gear Based on Pro/E

In order to obtain 3D solid model of an Oerlikon system’s prolate epicycloidal bevel gear by full generating processing, the solid modeling method for the gear was studied in Pro/E. First, Drawing benchmark circles (base on the circle and reference circle as well as tip circle and root circle)and involute tooth profile of virtual equivalent gears of both large end and small end of the real gear, and then an intercepted segment of prolate epicycloid which has the same trend to the tooth and is controlled by prolate epicycloidal equations is projected to the surface of the gear’s root cone for the sake of getting tooth curve along axial direction. In the end, along the tooth curve and on the root cone conducting a variable cross section solid scanning to tooth shaped cross section, a complete gear tooth will be gained and at last model establishing will be finished. This method provided digital basis for optimization design, reverse design and rapid prototyping of this kind of gear, and so its design efficiency is improved.