EVOLUTION, Issue 10 2006
C. D. Hulsey
Abstract The extent to which elements of functional systems can change independently (modularity) likely influences the diversification of lineages. Major innovations in organismal design, like the pharyngeal jaw in cichlid fishes, may be key to a group's success when they relax constraints on diversification by increasing phenotypic modularity. In cichlid fishes, pharyngeal jaw modifications that enhanced the ability to breakdown prey may have freed their oral jaws from serving their ancestral dual role as a site of both prey capture and prey processing. This functional decoupling that allowed the oral jaws to become devoted solely to prey capture has been hypothesized to have permitted the two sets of cichlid jaws to evolve independently. We tested the hypothesis that oral and pharyngeal jaw mechanics are evolutionarily decoupled both within and among Neotropical Heroine cichlids. In the trophically polymorphic species Herichthys minckleyi, molariforms that exhibit enlarged molarlike pharyngeal jaw teeth were found to have approximately 400% greater lower jaw mass compared to H. minckleyi with the alternative papilliform pharyngeal morphology. However, oral jaw gape, lower jaw velocity ratios, anterior jaw linkage mechanics, and jaw protrusion did not differ between the morphotypes. In 40 other Heroine species, there was a weak correlation between oral jaw mechanics and pharyngeal jaw mass when phylogenetic history was ignored. Yet, after expansion of the cytochrome b phylogeny for Heroines, change in oral jaw mechanics was found to be independent of evolutionary change in pharyngeal jaw mass based on independent contrasts. Evolutionary decoupling of oral and pharyngeal jaw mechanics has likely played a critical role in the unparalleled trophic diversification of cichlid fishes. [source]

Perspective: Assessing the Clinical Utility of Serum CTX in Postmenopausal Osteoporosis and Its Use in Predicting Risk of Osteonecrosis of the Jaw,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2009
Sanford Baim
Abstract Bone turnover markers (BTMs) have become increasingly important in the management of postmenopausal osteoporosis (PMO). In bisphosphonate-treated women with PMO, BTMs can provide early indications of treatment efficacy, are predictors of BMD response and fracture risk reduction, and are potentially useful for monitoring patient compliance. The bone resorption marker serum C-telopeptide cross-link of type 1 collagen (sCTX) has shown high sensitivity and specificity for the detection of increased bone resorption. Recently, sCTX has been singled out as a potential indicator of risk of osteonecrosis of the jaw (ONJ) in patients receiving oral bisphosphonates who require oral surgery. However, whether BTMs are capable of predicting ONJ risk and whether sCTX is usable for this purpose are controversial questions. This article presents an overview of the current literature regarding critical issues affecting the clinical utility of BTMs (including variability and reference ranges) and the current applications of BTMs in PMO management, with a focus on sCTX. Last, the appropriateness of using sCTX to predict ONJ risk in women receiving oral bisphosphonates for PMO is evaluated. [source]

Bisphosphonate-Associated Osteonecrosis of the Jaw: Report of a Task Force of the American Society for Bone and Mineral Research,,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2007
Sundeep Khosla (Chair)
Abstract ONJ has been increasingly suspected to be a potential complication of bisphosphonate therapy in recent years. Thus, the ASBMR leadership appointed a multidisciplinary task force to address key questions related to case definition, epidemiology, risk factors, diagnostic imaging, clinical management, and future areas for research related to the disorder. This report summarizes the findings and recommendations of the task force. Introduction: The increasing recognition that use of bisphosphonates may be associated with osteonecrosis of the jaw (ONJ) led the leadership of the American Society for Bone and Mineral Research (ASBMR) to appoint a task force to address a number of key questions related to this disorder. Materials and Methods: A multidisciplinary expert group reviewed all pertinent published data on bisphosphonate-associated ONJ. Food and Drug Administration drug adverse event reports were also reviewed. Results and Conclusions: A case definition was developed so that subsequent studies could report on the same condition. The task force defined ONJ as the presence of exposed bone in the maxillofacial region that did not heal within 8 wk after identification by a health care provider. Based on review of both published and unpublished data, the risk of ONJ associated with oral bisphosphonate therapy for osteoporosis seems to be low, estimated between 1 in 10,000 and <1 in 100,000 patient-treatment years. However, the task force recognized that information on incidence of ONJ is rapidly evolving and that the true incidence may be higher. The risk of ONJ in patients with cancer treated with high doses of intravenous bisphosphonates is clearly higher, in the range of 1,10 per 100 patients (depending on duration of therapy). In the future, improved diagnostic imaging modalities, such as optical coherence tomography or MRI combined with contrast agents and the manipulation of image planes, may identify patients at preclinical or early stages of the disease. Management is largely supportive. A research agenda aimed at filling the considerable gaps in knowledge regarding this disorder was also outlined. [source]

Osteonecrosis of the Jaw: More Research Needed,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2006
Elizabeth Shane
No abstract is available for this article. [source]

Temporary Intermaxillary Fixation using Individualized Acrylic Splints Permits Image,Data-Based Surgery of the Lower Jaw and Oropharynx

THE LARYNGOSCOPE, Issue 8 2004
Jürgen Hoffmann MD
Abstract Objectives/Hypothesis: Image,data-based surgical navigation is used as a helpful device in the operating room to localize critical structures with a high degree of accuracy. It also enables physicians to plan therapeutic performance. Because it relies on preoperatively acquired computed tomography (CT) or magnetic resonance imaging (MRI) data, there is restricted access for navigation of surgical instruments in areas that show motion uncorrelated with radiologic data. Thus, in the case of moveable structures, for example the lower jaw, navigational procedures could not yet be applied. Study Design: We introduce a new technique using individualized intermaxillary splints that fix the mandible in a reproducible aboccluded position at the time of image-data acquisition and surgery. Methods: Different manufacturing processes were investigated. The feasibility of uni- and bilateral intermaxillary splints was studied under clinical conditions in four patients during different procedures in the mandibular and oropharyngeal regions. Results: The manufacturing of the splints showed was easily performed in a short time. With bilateral fixation, there was a high anatomic target precision of 1.6 to 2.3 mm. Conclusions: The use of bilateral intermaxillary splints that fix the patient's mandible in a reproducible aboccluded position permits an image,data-based navigated surgical approach to the oropharyngeal and mandibular regions. [source]

Clinical Experiences of Computer Numeric Control-Milled Titanium Frameworks Supported by Implants in the Edentulous Jaw: A 5-Year Prospective Study

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 4 2004
Anders Örtorp DDS
ABSTRACT Background: Few long-term follow-up studies on treatment concepts using computer numeric control-milled titanium frameworks have been conducted. Objective: To evaluate the clinical and radiographic performance of implant-supported prostheses provided with computer numeric control-milled titanium frameworks in the edentulous jaw and to compare their performance during the first 5 years of function with that of prostheses provided with conventional cast gold alloy frameworks. Materials and Methods: A consecutive group of 126 edentulous patients were randomly provided with 67 prostheses with titanium frameworks (test group) in 23 upper jaws and 44 lower jaws and with 62 conventional prostheses with gold alloy castings (control group) in 31 upper jaws and 31 lower jaws. Clinical and radiographic 5-year data were collected for the test and control groups. Results: The frequency of problems was low, and clinical and radiologic performances were similar in both groups. In the test group, the 5-year cumulative survival rates (CSRs) were 94.9% and 98.3% for implants and titanium prostheses, respectively. The respective corresponding CSRs for the control group were 97.9% and 98.2%. More loaded implants were lost in the maxillas in the test group (p < .01), but this difference was not significant on the patient/prosthesis level (p > .05). Smokers lost more implants than nonsmokers lost (p < .01). Similar survival rates were observed for implants in the mandible. One prosthesis was lost in each group because of the loss of implants. Metal fractures were seen only in the control group, and resin veneer fractures were more frequent in the maxilla in the gold alloy group (p < .05). In the test group, the mean marginal bone loss was 0.5 mm (SD, 0.44) in the maxilla and 0.4 mm (SD, 0.50) in the mandible. A similar pattern of bone reaction was observed in the control group. Mean marginal bone loss was similar for smokers and nonsmokers (p > .05). Conclusion: Computer numeric control-milled titanium frameworks are a viable alternative to gold alloy castings in the edentulous jaw and present clinical and radiologic performances similar to those of conventional gold alloy frameworks during the first 5 years of function. [source]

The Marius Implant Bridge: Surgical and Prosthetic Rehabilitation for the Completely Edentulous Upper Jaw with Moderate to Severe Resorption: A 5-Year Retrospective Clinical Study

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2 2002
Yvan Fortin DDS
ABSTRACT Background: Patients seeking replacement of their upper denture with an implant-supported restoration are most interested in a fixed restoration. Accompanying the loss of supporting alveolar structure due to resorption is the necessity for lip support, often provided by a denture flange. Attempts to provide a fixed restoration can result in compromises to oral hygiene based on designs with ridge laps. An alternative has been an overdenture prosthesis, which provides lip support but has extensions on to the palate and considerations of patient acceptance. The Marius bridge was developed as a fixed bridge alternative offering lip support that is removable by the patient for hygiene purposes, with no palatal extension beyond normal crown-alveolar contours. Purpose: Implant-supported restorative treatment of completely edentulous upper jaws, as an alternative to a complete denture, is frequently an elective preference, and it requires significant patient acceptance beyond the functional improvement of chewing. Patients with moderate to severe bone resorption and thin ridges present additional challenges for adequate bone volume and soft-tissue contours. The purpose of this investigation was to develop a surgical and prosthetic implant treatment protocol for completely edentulous maxillae in which optimal lip support and phonetics is achieved in combination with substantial implant anchorage without bone grafting. Materials and Methods: The Marius bridge is a complete-arch, double-structure prosthesis for maxillae that is removable by the patient for oral hygiene. The first 45 consecutive patients treated by one person (YF) in one center with this concept are reported, with 245 implants followed for up to 5 years after prostheses connection. Results: The cumulative fixture survival rate for this 5-year retrospective clinical study was 97%. Five fixtures failed before loading, in five different patients, and two fixtures in the same patient failed at the 3-year follow-up visit. None of the bridges failed, giving a prostheses survival rate of 100%. The complications were few and mainly prosthetic: nine incidences of attachment component complications, one mesobar fracture, and three reports of gingivitis. All complications were solved or repaired immediately, with minimal or no interruption of prostheses use. Conclusions: Satisfactory medium-term results of survival and patient satisfaction show that the Marius bridge can be recommended for implant dentistry. The technique may reduce the need for grafting, because it allows for longer implants to be placed with improved bone anchorage and prostheses support. [source]

Clinical Experiences of CNC-Milled Titanium Frameworks Supported by Implants in the Edentulous Jaw: 1-Year Prospective Study

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 1 2000
Anders Örtorp LDS
ABSTRACT Background: A new type of titanium framework has been introduced, but so far no clinical reports have been made in this treatment modality. Purpose: The aim of this study was to report the clinical performance of implant-supported prostheses with computer numeric controlled (CNC)-milled titanium frameworks in the edentulous jaw and to compare the results with prostheses provided with conventional cast frameworks during the first year of function. Material and Methods: A consecutive group of 65 patients with 67 prostheses were provided with CNC-milled titanium frameworks in 23 upper and 44 lower jaws. During the same period, 61 consecutive patients were treated on a routine basis with 31 upper and 31 lower conventional gold alloy casting prostheses. Clinical and radiographic 1-year data were collected for both the test and control groups. Results: A total of 14 of 729 inserted implants were lost during the follow-up period (1.9%). All prostheses were functioning after 1 year except a conventional prosthesis with a cast framework, which was replaced by an implant-supported over-denture due to implant loss. The 1-year cumulative survival rate (CSR) was 100% and 97.8% for CNC prostheses and implants, respectively. The corresponding CSR for the control group was 98.3% and 98.3%, respectively. Few problems were reported in both groups, and the clinical and the radiologic performances were similar for both groups. No mechanical complications except some resin veneer fractures (n = 6) were observed. The mean marginal bone loss for the test group during the first year in function was 0.4 mm (SD = 0.35) and 0.4 mm (SD = 0.33) in the upper and lower jaws, respectively. A similar pattern of bone reaction was also observed in the control group. Conclusion: CNC-milled titanium frameworks can be used as an alternative to conventional castings in the edentulous jaw, presenting similar clinical and radiologic performances as conventional cast frameworks during the first year of function. [source]

Outcome of Oral Implant Treatment in Partially Edentulous Jaws Followed 20 Years in Clinical Function

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 4 2006
Odont Dr/PhD, Ulf Lekholm DDS
ABSTRACT Background:, Most long-term follow-up studies of implants in partially edentulous jaws present their outcomes as mean values of implant survival and follow-up time, and few address the fate of the remaining teeth. Purpose:, The aim of this study was to investigate the results of oral implant treatment in partially edentulous jaws after 20 years, and simultaneously to assess what happens to teeth present at the time of implant placement. Materials and Methods:, Seventeen partially edentulous patients, of 27 originally treated individuals, were retrospectively reviewed after receiving implants from 1983 to 1985. The parameters studied were implant survival, prosthesis stability, marginal bone loss at teeth and implants, treatment complications, need for dental treatment, and patient's satisfaction with the outcome. Results:, The cumulative survival rate was 91%, when all 27 patients were assessed, that is, including the 10 dropouts. Of the 69 inserted and followed implants (Brånemark system®; Nobel Biocare AB, Göteborg, Sweden), six failed (8.7%) during the 20-year period, four during the first decade, and the remaining two during the second. A majority (n=4) of the losses were due to implant fractures, two after 8 years, and two after 17 years. In all, 10 of the original fixed bridges being followed (n=24) remained in function during the entire investigation period, whereas 12 were exchanged for new constructions after an average of 7 years. The mean marginal bone loss at teeth was 0.7 mm, and at implants it was 1.0 mm. The major complication observed during the second decade was veneer material fractures, which occurred 14 times in six patients. Component loosening and abutment- and bridge-locking screw fractures were the second most common problems seen, indicating material/component fatigue. Most patients were satisfied with their treatment and many mentioned that they did not think of the constructions as anything but a part of their own body. Conclusion:, Over the decades, treatment of partially edentulous jaws with turned titanium implants seems to function well and to provide patients with good support for fixed short-span bridge constructions. [source]

Report of a Case Receiving Full-Arch Rehabilitation in Both Jaws Using Immediate Implant Loading Protocols: A 1-Year Resonance Frequency Analysis Follow-Up

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 1 2006
Michael Portmann DDS
ABSTRACT Background:, Immediate occlusal implant loading has been documented as a viable treatment option for various indications. However, documentations related to full-arch rehabilitation are usually limited to treatment of one jaw at a time, thereby leaving the opposing dentition unchanged. Furthermore, clinical documentation using traditional, well-accepted measuring techniques may not be adequate when it comes to short-term evaluation of the success or failure of implants subjected to immediate occlusal loading. Purpose:, The purpose of this case report is to (1) present an implant stability follow-up of a patient receiving an immediate, implant-supported full-arch rehabilitation in both jaws and (2) evaluate the patient's acceptance of this rehabilitation. Materials and Methods:, A 68-year-old patient scheduled for implant treatment was selected for an immediate implant loading protocol in both jaws. During two surgical events 3 weeks apart, eight maxillary and four mandibular Brånemark System® Mk IV TiUniteTM fixtures (Nobel Biocare AB, Göteborg, Sweden) were inserted and subsequently used to immediately support a cross-arch fixed prosthesis in the maxilla and a bar-retained overdenture in the mandible. Implant stability was recorded from the day of surgery periodically during a 1-year follow-up using resonance frequency analysis (RFA). Results:, At the 1-year follow-up, based on clinical, RFA, and radiographic evaluations, all implants and the reconstructions were classified as successful. All maxillary implants showed a decrease in the implant stability quotient (ISQ) value from the measurement at the time of surgery to the first follow-up, whereas two of four mandibular implants revealed an initial drop in stability. Irrespective of a specific ISQ level measured at implant surgery (ISQ range 53,74) and despite an initial decrease in stability, measurements recorded at the 12-month follow-up indicated similar stability levels for all maxillary implants (ISQ range 64,68) or the group of mandibular implants (ISQ range 72,75) but with a higher ISQ level for mandibular implants. Furthermore, the patient's acceptance of the immediate full-arch rehabilitation in both jaws was high. Conclusions:, The present case report demonstrates that a slightly staged approach for full-arch rehabilitation in both jaws using immediate implant loading protocols is a realistic treatment option. Furthermore, RFA follow-up indicates that immediately occlusally loaded implants placed in reduced bone quality and quantity are more prone to loose stability in the early healing period compared with implants placed in dense bone quality. [source]

Stability Measurements of Osseointegrated Implants Using Osstell in Partially Edentulous Jaws after 1 Year of Loading: A Pilot Study

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 3 2002
Piero Balleri MD
ABSTRACT Background: The introduction of resonance frequency analysis (RFA) as a commercially available technique has made it possible to measure implant stability in implant stability quotient (ISQ) units at any time during the course of implant treatment and loading. However, no information on normal ISQ levels can be found in the literature. Purpose: The aim of this pilot study was to measure the stability of clinically successful implants in partially edentulous patients after 1 year of loading and to study the influence of jaw, anterior/posterior position, implant length, and marginal bone level on implant stability. Materials and Methods: Fourteen partially edentulous patients previously treated with 45 implants were subjected to clinical and radiographie evaluations and RFA measurements using Osstell (Integration Diagnostics, Sävedalen, Sweden) after 1 year of loading. Results: All 45 implants were stable, and implant stability levels were in the range of 57 to 82 ISQ units with a mean of 69 ± 6.5 ISQ after 1 year of loading. Mandibular implants were more stable than were maxillary ones. There were no differences between anterior and posterior implants. No correlation could be found between implant length and stability. Only minor marginal bone resorption was observed. Conclusions: The results from this limited material showed that successfully integrated implants have ISQ levels from 57 to 82 ISQ with a mean of 69 ISQ after 1 year of loading. Mandibular implants are more stable than are maxillary ones. High implant stability can be achieved with short implants and placement in posterior regions. [source]

Fate of developing tooth buds located in relation to mandibular fractures in three infancy cases

DENTAL TRAUMATOLOGY, Issue 4 2010
Kazuhiko Yamamoto
Three infants, 2 girls and a boy, aged from 1 year and 5-months old to 2 years and 6-months old, were treated for dislocated mandibular fracture in the symphyseal region by manual reduction and fixation with a thermoforming splint and circumferential wiring under general anesthesia. Fracture healing was uneventful in all cases. A few years later, no obvious deformity of the jaw or malocclusion was observed; however, malformation of the crown was found in one of the permanent teeth on the fracture line in the first case. In the second case, no abnormality was observed in one of the permanent teeth on the fracture line, but the effect on the other tooth could not be evaluated due to abnormality of the tooth probably not related to the injury. In the third case, root formation was arrested in one of the permanent teeth on the fracture line and the tooth was lost early after eruption. The development of tooth buds on the fracture line is not predictable and therefore, should be monitored by regular follow up. [source]

Retinoic acid affects craniofacial patterning by changing Fgf8 expression in the pharyngeal ectoderm

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 9 2008
Makoto Abe
Retinoic acid signaling plays important roles in establishing normal patterning and cellular differentiation during embryonic development. In this study, we show that single administration of retinoic acid at embryonic day 8.5 causes homeotic transformation of the lower jaw into upper jaw-like structures. This homeosis was preceded by downregulation of Fgf8 and Sprouty expression in the proximal domain of the first pharyngeal arch. Downregulation of mesenchymal genes such as Dlx5, Hand2, Tbx1 and Pitx2 was also observed. The oropharynx in retinoic acid-treated embryos was severely constricted. Consistent with this observation, Patched expression in the arch endoderm and mesenchyme was downregulated. Thus, retinoic acid affects the expression of subsets of epithelial and mesenchymal genes, possibly disrupting the regional identity of the pharyngeal arch. [source]

Comparative ontogeny and phylogeny of the upper jaw skeleton in amniotes

DEVELOPMENTAL DYNAMICS, Issue 5 2006
Joy M. Richman
Abstract The morphology, position, and presence of the upper jaw bones vary greatly across amniote taxa. In this review, we compare the development and anatomy of upper jaw bones from the three living amniote groups: reptiles, birds, and mammals. The study of reptiles is particularly important as comparatively little is known about the embryogenesis of the jaw in this group. Our review covers the ontogeny and phylogeny of membranous bones in the face. The aim is to identify conserved embryonic processes that may exist among the three major amniote groups. Finally, we discuss how temporal and spatial regulation of preosseous condensations and ossification centers can lead to variation in the morphology of amniote upper jaw bones. Developmental Dynamics 235:1230,1243, 2006. © 2006 Wiley-Liss, Inc. [source]

Expression of zebrafish six1 during sensory organ development and myogenesis

DEVELOPMENTAL DYNAMICS, Issue 4 2004
Dmitri A. Bessarab
Abstract Drosophila sine oculis homologous genes in vertebrates are homeobox-containing transcription factors functioning within the Pax-Six-Eya-Dach regulatory network during development. In this study, we describe the cloning and expression of a zebrafish homolog of sine oculis, six1. The reverse transcription-polymerase chain reaction demonstrated accumulation of six1 transcripts at mid-gastrula, and in situ hybridization showed their subsequent expression in the cranial placode and later in the olfactory, otic, and lateral line placodes, inner ear, and neuromasts. In addition, six1 is expressed in the pituitary, branchial arches, somites, pectoral fin, ventral abdomen muscle, and the cranial muscles of the eye and lower jaw. An increase of six1 expression was observed in the lateral line, muscles, and inner ear of the mind bomb mutant, illustrating a regulatory effect of the Notch pathway on expression of Six genes. Developmental Dynamics 230:781,786, 2004 © 2004 Wiley-Liss, Inc. [source]

Lower motor neuron involvement in perisylvian polymicrogyria

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 10 2006
Maria Clark MB BChir MRCP
Congenital bilateral perisylvian polymicrogyria syndrome (CBPS) has a cerebral cortical localization and its phenotype was thought to be purely central. This study of seven children with CBPS (five males, two females; mean age 5y [SD 3y 6mo]; range 1mo-11y 10mo) documents electrophysiological evidence of lower motor neuron involvement in association with congenital contractures (limb or jaw) in six of the seven children studied. This is not an expected association and does not conform to the traditional lesional classification system of the cerebral palsies. Possible pathogenic mechanisms are discussed but this association of upper and lower motor neuron involvement is likely to be a previously unsuspected part of a genetic or other pathogenic sequence. [source]

Fine needle aspiration cytology in a case of fibrous dysplasia of jaw

DIAGNOSTIC CYTOPATHOLOGY, Issue 12 2009
Nalini Gupta M.D.
Abstract Fibro-osseous lesions of the jaw comprise of a spectrum of diseases which include osseous dysplasia, fibrous dysplasia, and ossifying fibroma. The differentiation amongst these individual pathological lesions is difficult and a combined clinico-radiological and histological correlation is essential for exact categorization. Fine needle aspiration cytology (FNAC) is frequently carried out to distinguish between benign and malignant lesions of the jaw as is a quick and reliable modality of investigation which guides in further management. We report, a case of a jaw swelling in a young male, diagnosed as fibrous dysplasia on FNAC. Diagn. Cytopathol. 2009. © 2009 Wiley-Liss, Inc. [source]

A new specimen of Helicoprion Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function

ACTA ZOOLOGICA, Issue 2009
O. A. Lebedev
Abstract A new Helicoprion bessonowi Karpinsky, 1899 (Chondrichthyes, Eugeneodontiformes) specimen from the Artinskian of Kazakhstan is described. This is the southernmost occurrence of this species in the Cisurals area. Its presence suggests a biogeographical link for this species between the Cisurals and Japan. Residue obtained from chemical preparation of the sample included numerous scales and several teeth, which are tentatively assigned to Helicoprion. This assumption is based upon morphological similarity of the scales to those known in other eugeneodontiforms. Campodus -like teeth might be part of the lateral dentition of Helicoprion. A new reconstruction of the interaction of the lower tooth whorl with the upper jaw dentition is suggested and its function is discussed. It is proposed that there was no symphysial whorl in the upper jaw but its role was played by a rigid cover formed by a series of small teeth at the palatoquadrates. Microscopic study of the tooth crown surface revealed scratch marks, which might have resulted from pressing the food object against the upper jaw. Using extant odontocetans as an ecological model led to a conclusion that helicoprionids most likely fed on cephalopods and to some extent on fish. This assumption is based upon the concentration of functional dentition in the area of the lower jaw symphysis in both groups of animals. [source]

Ultrastructural study of the jaw structures in two species of Ampharetidae (Annelida: Polychaeta)

ACTA ZOOLOGICA, Issue 3 2004
Alexander B. Tzetlin
Abstract Two species of jaw bearing Ampharetidae (Adercodon pleijeli (Mackie 1994) and Ampharete sp. B) were investigated in order to describe the microanatomy of the mouth parts and especially jaws of these enigmatic polychaetes. The animals of both studied species have 14,18 mouth tentacles that are about 30 µm in diameter each. In both species, the ventral pharyngeal organ is well developed and situated on the ventral side of the buccal cavity. It is composed of a ventral muscle bulb and investing muscles. The bulb consists of posterior and anterior parts separated by a deep median transversal groove. In both species, the triangular teeth or denticles are arranged in a single transversal row on the surface of the posterior part of the ventral bulb just in front of its posterior edge. There are 36 denticles in Adercodon pleijeli and 50 in Ampharete sp. B. The height of the denticles (6,12 µm) is similar in both species. Each tooth is composed of two main layers. The outer one (dental) is the electron-dense sclerotized layer that covers the tooth. The inner one consists of long microvilli with a collagen matrix between them. The thickness of the dental layer ranges from 0.95 to 0.6 µm. The jaws of the studied worms may play a certain role in scraping off microfouling. The fine structure of the jaws in Ampharetidae is very similar to that of the mandibles of Dorvilleidae, the mandibles and the maxillae of Lumbrineridae, Eunicidae and Onuphidae, and the jaws of other Aciculata. This type of jaw is characterized by unlimited growth and the absence of replacement. The occurrence of jaws in a few smaller Ampharetidae is considered as an apomorphic state. [source]

Oral sodium clodronate induced osteonecrosis of the jaw in a patient with myeloma

EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2007
Amir H Montazeri
Abstract Bisphosphonate therapy has been shown to significantly reduce the incidence of skeletal complications in patients with myeloma. Several recent reports have described osteonecrosis of the jaw (ONJ) associated with bisphosphonates. These reports mainly demonstrate an association between ONJ and potent i.v. bisphosphonates. We report a case of ONJ in a patient with myeloma, who had only been treated with oral sodium clodronate. While the degree of risk for osteonecrosis in patients taking oral bisphosphonates, such as clodronate, remains uncertain it would be prudent to consider carefully the indications for the use of these agents to minimise the risk of ONJ. [source]

MICRO- AND MACROEVOLUTIONARY DECOUPLING OF CICHLID JAWS: A TEST OF LIEM'S KEY INNOVATION HYPOTHESIS

Oral hygiene and the need for treatment of the dependent institutionalised elderly

GERODONTOLOGY, Issue 2 2006
Sylvie Montal
Objective:, To assessing the oral hygiene and treatment needs of a geriatric institution in southern France. Background:, For various reasons, the care demand from elderly people is low and difficult to determine, whereas their oral status would need long and complicated treatments. Materials and methods:, From 2003 to 2004, a cross-sectional study of 321 elderly patients was conducted at several geriatric services of Montpellier, France. The clinical evaluation of dental status was recorded together with medical information. Dental and prosthetic hygiene, status of dentures, caries experience, dependence conditions and treatment needs were evaluated. Results:, The prevalence of edentulism was 27%, with no gender difference (23% of the men and 29% of the women). Among them, 16.7% (upper jaw) and 18.1% (lower jaw) were totally edentulous with no denture. The mean number of decayed and missing teeth was 3.7 for men and 2.8 for women and 21.5 for men and 21.0 for women, respectively. The mean number of filled teeth was 0.8 for men and 1.3 for women, with no statistical difference according to gender for the three indexes. Most of the subjects needed prostheses (53%), 45.1% extractions and 30.6% conservative treatments. Only 2.4% did not need any treatment. Conclusion:, The prevalence of edentulism was relatively low, while the need for prosthodontic rehabilitation, especially for men, was still very high. The dental hygiene was globally inadequate. This evaluation emphasises the care demand and the need for help in oral hygiene procedures for the dependent institutionalised elderly. [source]

Responses of jawbone to pressure,

GERODONTOLOGY, Issue 2 2004
Gunnar E. Carlsson
Objective:, To provide a literature review of bone resorption of edentulous jaws focusing on responses to pressure. Background:, After the extraction of all teeth in a jaw there is a continuous reduction of the residual ridge. The individual variation of bone resorption is great, and the aetiology is complex and not yet well understood. Materials and methods:, A search of the literature published up to May 2003 on bone resorption and pressure was performed using PubMed/Medline. Results:, Animal studies have demonstrated that excessive and constant pressure induces bone resorption. Recent experimental research has indicated that bone resorption is a pressure-regulated phenomenon with a lower threshold for continuous than for intermittent pressure. Clinical studies have suggested that residual ridge resorption is due more to the effects of denture wearing than to disuse atrophy. However, the results of leaving out dentures at night are not conclusive. Nor does the literature offer any strong evidence for the so-called combination syndrome, which has been described as a result of unfavourable loading. Clinical studies using multivariate analyses indicate that female gender and systemic factors may be of greater importance than oral and denture factors. Implant-supported prostheses have a bone preserving effect rather than the continuing resorption under complete dentures. Conclusions:, The best way to reduce bone resorption is to avoid total extraction, preserve a few teeth and fabricate overdentures. In edentulous jaws, placement of implant-supported prostheses will lead to less bone loss and may even promote bone growth. To increase our knowledge of residual ridge resorption extended experimental, clinical and statistical methods will be needed, preferably including collaboration between dental and medical researchers. [source]

Patients with bisphosphonates-associated osteonecrosis of the jaw have reduced circulating endothelial cells

HEMATOLOGICAL ONCOLOGY, Issue 4 2007
A Allegra
Abstract Osteonecrosis of the jaws (ONJ) associated with the use of bisphosphonates is a newly described entity. To elucidate the mechanism leading to ONJ and to test the hypothesis that in patients with ONJ the bisphosphonates may interfere with endothelial cell proliferation, using flow cytometric analysis we evaluated the number of circulating endothelial progenitor cells (EPCs) and circulating endothelial cells (CECs) in eight patients with bisphosphonate treatment and osteonecrosis, eight multiple myeloma (MM) patients with bisphosphonates treatment without ONJ and five normal subjects. MM patients showed an increase of CD34+ cells with respect the control subjects and ONJ subjects. EPCs and CECs were higher in MM patients compared to controls and ONJ patients. ONJ patients showed a decrease of EPCs compared to control subjects while CECs were similar to the controls group. Our results seem to show the possibility that bisphosphonates could have a antiangiogenic effect and a suppressive effect on CECs of patients with ONJ. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Identification of a novel mutation of SH3BP2 in cherubism and demonstration that SH3BP2 mutations lead to increased NFAT activation ,,

HUMAN MUTATION, Issue 7 2006
Steven A. Lietman
Abstract We describe a novel missense mutation (Aspartic acid to Asparagine, p.D419N (g.1371G>A, c.1255G>A) within exon 9 of SH3BP2 in a patient with cherubism, an autosomal dominant syndrome characterized by excessive osteoclastic bone resorption of the jaw. Two siblings and the father were carriers but lacked phenotypic features. Transient expression of p.D419N (c.1255G>A), as well as three previously described exon 9 mutations from cherubism patients (p.R415Q (c.1244G>A), p.D420E (c.1259G>A), and p.P418R (c.1253C>G)) increased activity of NFAT (nuclear factor of activated T-cells), an osteoclastogenic mediator, indicating that cherubism results from gain of function mutations in SH3BP2. Published 2006 Wiley-Liss, Inc. [source]

When managing established osteonecrosis of the jaw, don't forget the not-infrequent chronic refractory pain

INTERNAL MEDICINE JOURNAL, Issue 3 2010
P. Poon
No abstract is available for this article. [source]

Mandibular hypodontia and osteoarthritis in prehistoric bighorn sheep (Ovis canadensis) in eastern Washington State, USA

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 4 2010
R. Lee Lyman
Abstract Mandibular hypodontia of the p2 was found to occur in 3 out of 21 individual prehistoric Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from Moses Coulee Cave in eastern Washington State, similar to its frequency of occurrence in modern bighorn. There is no evidence of lumpy jaw (mandibular osteomyelitis) in the Moses Coulee Cave collection. Evidence from Moses Coulee Cave aligns with the hypothesis that low frequencies of hypodontia and lumpy jaw occur in healthy, evolutionarily old (maintenance) populations in order to maintain the occlusal area and thus maximise efficiency of food procurement and processing. Osteoarthritis was found to occur in 1 out of 70 individual Rocky Mountain bighorn sheep (Ovis canadensis canadensis) astragali in the Moses Coulee Cave collection. This prevalence is unsurprising given a population dominated by prime-age individuals. Osteoarthritis was likely selected against given that individuals must be agile to effectively use rugged terrain to escape predation and as a general measure suggests a healthy population. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Evolution of the vertebrate jaw: comparative embryology and molecular developmental biology reveal the factors behind evolutionary novelty

JOURNAL OF ANATOMY, Issue 5 2004
Shigeru Kuratani
Abstract It is generally believed that the jaw arose through the simple transformation of an ancestral rostral gill arch. The gnathostome jaw differentiates from Hox -free crest cells in the mandibular arch, and this is also apparent in the lamprey. The basic Hox code, including the Hox -free default state in the mandibular arch, may have been present in the common ancestor, and jaw patterning appears to have been secondarily constructed in the gnathostomes. The distribution of the cephalic neural crest cells is similar in the early pharyngula of gnathostomes and lampreys, but different cell subsets form the oral apparatus in each group through epithelial,mesenchymal interactions: and this heterotopy is likely to have been an important evolutionary change that permitted jaw differentiation. This theory implies that the premandibular crest cells differentiate into the upper lip, or the dorsal subdivision of the oral apparatus in the lamprey, whereas the equivalent cell population forms the trabecula of the skull base in gnathostomes. Because the gnathostome oral apparatus is derived exclusively from the mandibular arch, the concepts ,oral' and ,mandibular' must be dissociated. The ,lamprey trabecula' develops from mandibular mesoderm, and is not homologous with the gnathostome trabecula, which develops from premandibular crest cells. Thus the jaw evolved as an evolutionary novelty through tissue rearrangements and topographical changes in tissue interactions. [source]

Seasonal changes in the lower jaw skeleton in male Atlantic salmon (Salmo salar L.): remodelling and regression of the kype after spawning

JOURNAL OF ANATOMY, Issue 5 2003
P. Eckhard Witten
Abstract The return of Atlantic salmon (Salmon salar) to their home river for spawning coincides with drastic skeletal alterations in both sexes. Most prominent is the development of a kype (hook) at the tip of the lower jaw in males. Salmon that survive spawning have to cope with the kype throughout their life, unless it disappears after spawning, as was suggested in the early literature. To understand the fate of the kype skeleton, we compared morphological and histological features of kypes from pre-spawned mature anadromous males (grilse) with post-spawned males (kelts). The kype of male grilse is supported by fast-growing skeletal needles that differ from regular dentary bone. In kelts, growth of the kype skeleton has stopped and skeletal needles are resorbed apically by osteoclasts. Simultaneously, and despite the critical physiological condition of the animals, proximal parts of the kype skeleton are remodelled and converted into regular dentary bone. Apical resorption of the skeleton explains reports of a decrease of the kype in kelts. The conversion of basal kype skeleton into regular dentary bone contributes to the elongation of the dentary and probably also to the development of a larger kype in repetitive spawning males. [source]

Cell-based immunotherapy with mesenchymal stem cells cures bisphosphonate-related osteonecrosis of the jaw,like disease in mice

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2010
Takashi Kikuiri
Abstract Patients on high-dose bisphosphonate and immunosuppressive therapy have an increased risk of bisphosphonate-related osteonecrosis of the jaw (BRONJ); despite the disease severity, its pathophysiology remains unknown, and appropriate therapy is not established. Here we have developed a mouse model of BRONJ-like disease that recapitulates major clinical and radiographic manifestations of the human disease, including characteristic features of an open alveolar socket, exposed necrotic bone or sequestra, increased inflammatory infiltrates, osseous sclerosis, and radiopaque alveolar bone. We show that administration of zoledronate, a potent aminobisphosphonate, and dexamethasone, an immunosuppressant drug, causes BRONJ-like disease in mice in part by suppressing the adaptive regulatory T cells, Tregs, and activating the inflammatory T-helper-producing interleukin 17 cells, Th17. Most interestingly, we demonstrate that systemic infusion with mesenchymal stem cells (MSCs) prevents and cures BRONJ-like disease possibly via induction of peripheral tolerance, shown as an inhibition of Th17 and increase in Treg cells. The suppressed Tregs/Th17 ratio in zoledronate- and dexamethasone-treated mice is restored in mice undergoing salvage therapy with Tregs. These findings provide evidence of an immunity-based mechanism of BRONJ-like disease and support the rationale for in vivo immunomodulatory therapy using Tregs or MSCs to treat BRONJ. © 2010 American Society for Bone and Mineral Research [source]