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Dentition
Kinds of Dentition Terms modified by Dentition Selected AbstractsGingival Zenith Positions and Levels of the Maxillary Anterior DentitionJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2009STEPHEN J. CHU DMD ABSTRACT Purpose:, The location of the gingival zenith in a medial-lateral position relative to the vertical tooth axis of the maxillary anterior teeth remains to be clearly defined. In addition, the apex of the free gingival margin of the lateral incisor teeth relative to the gingival zeniths of the adjacent proximal teeth remains undetermined. Therefore, this investigation evaluated two clinical parameters: (1) the gingival zenith position (GZP) from the vertical bisected midline (VBM) along the long axis of each individual maxillary anterior tooth; and (2) the gingival zenith level (GZL) of the lateral incisors in an apical-coronal direction relative to the gingival line joining the tangents of the GZP of the adjacent central incisor and canine teeth under healthy conditions. Materials and Methods:, A total of 240 sites in 20 healthy patients (13 females, 7 males) with an average age of 27.7 years were evaluated. The inclusion patient criteria were absence of periodontal disease, gingival recession, or gingival hypertrophy as well as teeth without loss of interdental papillae, spacing, crowding, existing restorations, and incisal attrition. GZP dimensions were measured with calibrated digital calipers for each individual tooth and within each tooth group in a medial-lateral direction from the VBM. GZLs were measured in an apical-coronal direction from a tangent line drawn on the diagnostic casts from the GZPs of the adjacent teeth. Results:, This study demonstrated that all central incisors displayed a distal GZP from the VBM, with a mean average of 1 mm. Lateral incisors showed a deviation of the gingival zenith by a mean of 0.4 mm. In 97.5% of the canine population, the GZP was centralized along the long axis of the canine. The mean distance of the contour of the gingival margin in an apical-coronal direction of the lateral incisors (GZL) relative to gingival line joining the tangent of the adjacent central and canine GZPs was approximately 1 mm. Conclusion:, This investigation revealed a GZP mean value of 1 mm distal from the VBM for the central incisor tooth group. The lateral incisors showed a mean average of 0.4 mm. Thecanine tooth group demonstrated almost no deviations of the GZP from the VBM. The GZL of the lateral incisors relative to the adjacent central incisor and canine teeth were more coronal by approximately 1 mm. These data could be used as reference points during esthetic anterior oral rehabilitation. CLINICAL SIGNIFICANCE The information presented in this article can be clinically applied to reestablish the proper intratooth GZPs of the maxillary anterior teeth during periodontal crown lengthening or root coverage procedures. In addition, the intra-arch gingival level of the lateral incisor gingival zenith relative to the adjacent central and canine teeth can be appropriately established. [source] Selecting Nanotechnology-Based Composites Using Colorimetric and Visual Analysis for the Restoration of Anterior Dentition: A Case ReportJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2004FRANK J. MILNAR DDS ABSTRACT Currently it is possible to use direct composites and layering techniques to replicate the complex internal structures, visible shape, color, and surface anatomy of natural teeth. To do so, however, requires dentists to understand the principles of nature and the science of dental materials to determine the most suitable restorative material for a specific indication. By incorporating relatively new technologies,colorimetric analysis, which provides computerized shade guide definitions of a tooth and essential information to verify shade mapping, and a new nanotechnology-based direct composite,into composite layering techniques, dentists can more predictably replicate the esthetics of natural teeth. This article presents a case in which both technologies, used in combination with a composite layering technique, contributed to the esthetic and functional restoration of the maxillary central incisors. [source] Dentition in the African catfishes Andersonia (Amphiliidae) and Siluranodon (Schilbeidae) previously considered toothlessJOURNAL OF FISH BIOLOGY, Issue 1 2004A. S. Golubtsov Based on light and scanning electron microscopic examination of their morphology, the dentition on both the premaxilla and dentary of Andersonia(Amphiliidae) and Siluranodon(Schilbeidae) catfishes is described from samples taken from tributaries of the White Nile in south-western Ethiopia. These monotypic African genera were previously believed to lack teeth on the lower jaw in Andersonia and on both jaws in Siluranodon. Siluranodon exhibits an ontogenetic reduction: teeth were less frequently found in larger individuals than in smaller ones. In contrast to the adults of all other schilbeids, whose oral teeth are arranged in multiserial (or at least, biserial) bands, Siluranodon has uniserial teeth on both the premaxilla and the dentary. The adaptive, ontogenetic and phylogenetic aspects of jaw-tooth reduction in catfishes are discussed. [source] Dentition and tooth replacement pattern in Chalcides (Squamata; Scincidae)JOURNAL OF MORPHOLOGY, Issue 2 2003Sidney Delgado Abstract This study was undertaken as a prerequisite to investigations on tooth differentiation in a squamate, the Canarian scincid Chalcides. Our main goal was to determine whether the pattern of tooth replacement, known to be regular in lizards, could be helpful to predict accurately any stage of tooth development. A growth series of 20 laboratory-reared specimens, aged from 0.5 month after birth to about 6 years, was used. The dentition (functional and replacement teeth) was studied from radiographs of jaw quadrants. The number of tooth positions, the tooth number in relation to age and to seasons, and the size of the replacement teeth were recorded. In Chalcides, a single row of pleurodont functional teeth lies at the labial margin of the dentary, premaxillary, and maxillary. Whatever the age of the specimens, 16 tooth positions were recorded, on average, in each quadrant, suggesting that positions are maintained throughout life. Replacement teeth were numerous whatever the age and season, while the number of functional teeth was subject to variation. Symmetry of tooth development was evaluated by comparing teeth two by two from the opposite side in the four jaw quadrants of several specimens. Although the relative size of some replacement teeth fitted perfectly, the symmetry criterion was not reliable to predict the developmental stage of the opposite tooth, whether the pair of teeth compared was left,right or upper,lower. The best fit was found when comparing the size of successive replacement teeth from the front to the back of the jaw. Every replacement tooth that is 40,80% of its definitive size is followed, in the next position on the arcade, by a tooth that is, on average, 20% less developed. Considering teeth in alternate positions (even and odd series), each replacement tooth was a little more developed than the previous, more anterior, one (0.5,20% when the teeth are from 10,40% of their final size). The latter pattern showed that tooth replacement occurred in alternate positions from back to front, forming more or less regular rows (i.e., "Zahnreihen"). In Chalcides, the developmental stage of a replacement tooth in a position p can be accurately predicted provided the developmental stage of the replacement tooth in position p-1 or, to a lesser degree, in position p-2 is known. This finding will be particularly helpful when starting our structural and ultrastructural studies of tooth differentiation in this lizard. J. Morphol. 256:146,159, 2003. © 2003 Wiley-Liss, Inc. [source] The Effect of Functional Dentition on Healthy Eating Index Scores and Nutrient Intakes in a Nationally Representative Sample of Older AdultsJOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 4 2009R. Bethene Ervin PhD Abstract Objective: The objectives of this study were to examine the associations between functional dentition and the Healthy Eating Index (HEI) scores and nutrient intakes among older adults in the United States. Methods: The sample consisted of 2,560 adults, 60 years and over from the National Health and Nutrition Examination Survey 1999-2002. We used multivariate linear regression to examine associations between functional dentition and HEI scores or nutrient intakes controlling for the potential confounding effects of age, race/ethnicity, education, smoking status, body mass index (BMI), self-reported health, and caloric intake. Dentate status was classified as: edentulous (no natural permanent teeth or implants), 1-20 teeth, or,21 teeth. A functional dentition was defined as having 21 or more teeth present. HEI scores and nutrient intakes were based on one 24-hour dietary recall. Results: Males with a functional dentition consumed slightly more fruit and had higher alpha- and beta-carotene intakes than edentulous males. Females with any natural teeth had higher vitamin C intakes than edentulous females. There were no significant associations between dentate status and any of the remaining HEI scores or nutrient intakes for either sex. Conclusions: Having a functional dentition did not contribute substantially to higher HEI scores or nutrient intakes in this nationally representative sample of older adults. However, older men and women with no teeth or those who wear dentures consumed fewer servings of fruits and vegetables, especially those rich in carotenes and vitamin C, than those with teeth. [source] Longitudinal Study of Non-cavitated Carious Lesion Progression in the Primary DentitionJOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 2 2006John J. Warren DDS Abstract Objectives: This study reports changes in non-cavitated tooth surface diagnoses after a 4-year period. Methods: Dental examinations were conducted for Iowa Fluoride Study cohort children who had non-cavitated lesions in the primary dentition and were also examined an average of 4 years later in the mixed dentition. Comparison of fluoride exposures, socioeconomic factors, and beverage consumption patterns were made between children who had lesions progress and those who did not. Results: Of 129 non-cavitated pit and fissure lesions in the first exams, 40 (31%) progressed to either frank decay or filled status, while among 132 non-cavitated smooth surface lesions, 7 (5%) were filled and none had frank decay in the second exam. No fluoride, socioeconomic status or beverage variables were significantly Associated with lesion progression. Conclusions: Non-cavitated smooth surface lesions rarely progressed in this age group, but nearly one-third of pit and fissure lesions progressed. [source] Frequency of intrusive luxation in deciduous teeth and its effectsDENTAL TRAUMATOLOGY, Issue 4 2010Vivian Carvalho Second, to investigate the sequelae of total and partial intrusive luxation in the primary anterior teeth and in their successors and finally, to establish whether the sequelae on both deciduous and permanent teeth were related to the child's age at the time of the intrusion. Data collected from records of 169 boys and 138 girls, all between the ages of zero and 10 years, who were undergoing treatment during the period of March 1996 to December 2004. The sample was composed of 753 traumatized deciduous teeth, of which 221 presented intrusive luxation injury. Children with ages ranging from one to 4 years were the most affected with falls being the main cause of intrusion. Of all intruded teeth 128 (57.9%) were totally intruded and 93 (42.1%) partially. Pulp necrosis/premature loss and color change were the most frequent sequelae in both total and partial intrusions. Concerning permanent dentition, the most common disturbances were color change and/or enamel hypoplasia. Both types of intrusion caused eruption disturbance. Total intrusion was the most frequent type of intrusive luxation. There was no significant correlation between the child's age at the time of intrusion and the frequency of subsequent sequela on primary injured teeth (P = 0.035), between the age at the time of injury and the developmental disturbances on permanent teeth (P = 0.140). [source] Traumatic injuries to permanent teeth in Turkish children, AnkaraDENTAL TRAUMATOLOGY, Issue 3 2009Ceyhan Altun From a total of 4956 children aged 6,12 years (mean age: 8.91 ± 1.95) applying to the Center, 472 children (9.5%) were found to have suffered dental injuries during a period of 2 years. Injuries were classified according to drawings and texts based on the WHO classification system, as modified by Andreasen and Andreasen. Injury rates were highest among children age 6 and ages 8,10. The most frequently injured permanent teeth were the maxillary central incisors (88.2%), and the maxillary right central permanent incisor made up 47.2% of all injured teeth. The most common cause of dental trauma was falling while walking or running (40.3%). Most injuries involved a single tooth (64.8%). The most common type of injury was enamel fracture (44.6%). There was a significant difference in gender, where boys more often suffered from a dental hard tissue and pulp injury than girls (P = 0.019), whereas there was no difference in gender (P = 0.248) in the distribution of periodontal injuries. Injuries were found to occur more frequently during the summer (P < 0.001). Children with increased overjet were 2.19 times more likely to have dental injuries than other children. Considering that the incidence of traumatic dental injury is highest among children ages 6 and ages 8,10 as well as the fact that patients with increased overjet are more prone to dental trauma, preventive orthodontic treatment in early mixed dentition may play an important role in reducing traumatic dental injuries. [source] Crown-root fracture of a lower first primary molar: report of an unusual caseDENTAL TRAUMATOLOGY, Issue 3 2008Gabriela da Rosa Götze Abstract,,, Dental traumas are highly prevalent lesions in primary teeth, but crown-root fractures are seldom observed in posterior teeth of this dentition. The aim of the present report was to describe the diagnosis, treatment, and a 24-month follow-up of an unusual case of complicated crown-root fracture in a lower first primary molar of a 3-year-old boy. [source] Multiple crown-root fractures in primary molars and a suspected subcondylar fracture following trauma: a report of a caseDENTAL TRAUMATOLOGY, Issue 2 2008Zahra Tejani Injuries to the primary dentition are usually luxations and mandibular fractures rarely occur. With trauma sustained to the chin, the posterior primary teeth are at increased risk of trauma and mandibular fractures can occur. The case discussed is of a 4-year-old female who presented 2 weeks following dental trauma with multiple primary molar fractures and a possible subcondylar fracture. The need for a detailed examination is emphasized and the management of the case under general anaesthesia is described. [source] Guidelines for the management of traumatic dental injuries.DENTAL TRAUMATOLOGY, Issue 4 2007Abstract ,, Trauma to the primary dentition present special problems and the management is often different as compared with permanent teeth. An appropriate emergency treatment plan is important for a good prognosis. Guidelines are useful for delivering the best care possible in an efficient manner. The International Association of Dental Traumatology (IADT) has developed a consensus statement after a review of the dental literature and group discussions. Experienced researchers and clinicians from various specialties were included in the group. In cases in which the data did not appear conclusive, recommendations were based on the consensus opinion of the IADT board members. The guidelines represent the current best evidence based on literature research and professional opinion. In this third article out of three, the IADT Guidelines for the management of traumatic injuries in the primary dentition, are presented. [source] Traumatic injuries to the primary dentition and effects on the permanent successors , a clinical follow-up studyDENTAL TRAUMATOLOGY, Issue 5 2006Sabine Sennhenn-Kirchner Abstract,,, This study investigated problems in the permanent dentition that, according to history and records, were attributable to dental alveolar injuries of the primary dentition. 106 children have been involved in the study, who had experienced primary anterior tooth trauma affecting a total of 200 teeth. Thirty-nine patients (81 teeth) were available for follow-up examinations. In 25% of the cases followed up, damage was found on the successors in the secondary dentition (16 children/20 teeth). In half of the cases, a comparatively mild form of lesion like enamel discoloration was observed. This was the result of an injury during the tooth maturation process causing enamel hypoplasia. Clinically more relevant were the dental deformities: cessation of root formation or retention caused by ankylosis, which made up the remaining 50% of cases. This was confirmed by clinical long-term observation. The different effects on the permanent teeth can only be detected by radiography after an interval of several months or may even be clinically assessed only after the eruption of the clinical crown. [source] Comparison of forces transmitted through different EVA mouthguardsDENTAL TRAUMATOLOGY, Issue 4 2006Craig F. Duhaime Abstract,,, Athletic mouthguards have been recommended for decades with varying levels of athlete acceptance. Issues related to compliance center around the ability to breath and speak while wearing the mouthguards. Fabrication techniques have changed over time to a two-layer ethylene vinyl acetate mouthguard fabricated on a high-pressure machine. The reported ideal thickness of these mouthguards has been somewhat variable depending on the sport and anticipated level of risk. Recent research however, has identified 4 mm as the optimal thickness of EVA. In this study an acrylic dental cast was fabricated and mounted to a drop impact fixture. Mouthguards of varying ply, thickness and palatal coverage were fabricated and tested in the fixture. Strain gauges and load cells were used to evaluate the effect of ply, thickness, and palatal coverage on the ability of these mouthguards to minimize transmitted forces. The purpose of this study was to identify those variables of mouthguard construction that will minimize the overall transmitted force of impact to the anterior dentition. [source] Clinical investigation of traumatic injuries in Yeditepe University, Turkey during the last 3 yearsDENTAL TRAUMATOLOGY, Issue 4 2005Nuket Sandalli Abstract,,, The aim of this study was to evaluate etiology, types of traumatic dental injuries, treatment and to determine the incidence of complications according to dental injuries in patients who referred to Yeditepe University, Faculty of Dentistry, Istanbul, Turkey. The study was based on the clinical data of the 161 traumatized teeth in 92 patients. WHO classification slightly modified by Andreasen & Andreasen for dental trauma was used. The causes and localization of trauma, traumatized teeth classification, treatment and complications were evaluated both primary and permanent teeth. The distribution of complications according to diagnosis and treatment of the injured teeth were evaluated. Of 35 (38%) girls and 56 (72%) boys with a mean age 7.6 ± 3.5 (ranging 1,14.2) participated to study and the mean followed up was 1.72 ± 1.28 years (ranging 0.10,3.8 years). From the 161 affected teeth, 69 (42.9%) were in primary teeth and 92 (57.1%) in permanent teeth. The highest frequency of trauma occurred in the 6,12 year age group. Overall boys significantly outnumbered girls by approximately 1:1.6. The most common type of injury in the primary and permanent teeth was seen as luxation (38%) and enamel fracture (20%) of the maxillary central incisors, respectively. Falls were the major sources of trauma both the primary (90%) and the permanent teeth (84%). In the primary dentition, the most common type of soft tissue injury is contusion (62.5%) and in the permanent dentition, it is laceration (49%). The most of the treatment choice was determined as examination only and extraction in primary teeth (58 and 24.6%, respectively) while it was applied as restoration and pulpectomy in permanent teeth (31.5 and 18.5%, respectively). Complications were recorded on 37 teeth (23%) with a most common type of necrosis (10.5%) and dental abscess (7.4%). Necrosis was more frequent in luxation whereas dental abscess were in crown fracture with pulpal involvement in both dentitions. The study showed that boys were more prone to dental traumas than girls. Falls were more frequent trauma type with a high complication risk. It reveals that the time of the immediate treatment showed the important predisposing factors that increase the success of treatment and decrease the risk of complication. The correct diagnosis of dental injuries is more important for eliminating the occurrence of complications. [source] Dental injury among Brazilian schoolchildren in the state of São PauloDENTAL TRAUMATOLOGY, Issue 3 2004Sylvia Grimm Abstract ,,,To describe the distribution of dental trauma in Brazilian schoolchildren and its association with demographic, environmental and clinical factors. A random sample of 73 243 schoolchildren's oral examination records from private and public units, selected from 131 cities within the state of São Paulo, Brazil, was analysed. Trauma was assessed based on international methodological standards prescribed by the World Health Organization for Oral Health Surveys (1997). Proportions obtained were compared between urban and rural schools, as well as between private and public units. Oral health status indices were estimated based on the decayed, missing and filled teeth (DMFT) index , the average number of decayed, missing and filled teeth; the proportion of caries-free 5-year-old schoolchildren and anterior maxillary overjet among 12-year-old schoolchildren. The prevalence of dental trauma in anterior dentition was of 2.4, enrolling average 1.2 teeth per child. A rate of 2.4 impaired anterior teeth per thousand was obtained, upper central incisors being those that were most affected , 7.7 in every 10. Among 8- to 11-year-old children, the rates grew regularly. The proportion of dental trauma was significantly higher in boys than in girls (P < 0.01), and gender prevalence ratio was of 1.58 for boys. The results showed positive associations between dental trauma and caries-free 5-year-old schoolchildren (P = 0.003), anterior maxillary overjet,3 mm (P < 0.001), and private school as a socio-economic proxy indicator (P = 0.048). [source] Dental trauma in Turkish children, ,stanbulDENTAL TRAUMATOLOGY, Issue 2 2003Betul Kargul Abstract,,, Numerous studies focus on visits to dental clinics for emergent dental problems. Many are all-inclusive, studying traumatic injuries as well as visits for infection and other causes. Epidemiologic studies have focused on the investigation of the prevalence or incidence of dental injury. The patients were evaluated at Pediatric Dentistry, Marmara University Dental School, ,stanbul over a 2-year period. For these 300 patients (446 teeth), specific diagnoses were evaluated. Dental injuries that presented most frequently in permanent dentition were crown fractures of enamel only and crown fractures of enamel and dentin. The most frequently presented dental injury in primary dentition were avulsions and crown fractures of enamel. The more frequent treatments for primary teeth were examination only. Bandage restoration, space maintainer were common procedures for permanent teeth. [source] The prevalence of traumatic injuries treated in the pedodontic clinic of Ankara University, Turkey, during 18 monthsDENTAL TRAUMATOLOGY, Issue 6 2002Abstract , , ,The purpose of this study was to evaluate the type and prevalence of dental injuries referred to Ankara University, School of Dentistry, Department of Pedodontics, Turkey. One hundred and forty-seven patients with 234 traumatized teeth presented during 18-month interval. Of the 147 patients, 85 were boys and 62 were girls. The most frequent trauma occurred in the age of 11 years. The maxillary central incisors were found to be the most affected tooth in both primary and permanent dentition injuries. The maxillary arch is involved in a higher percentage of trauma cases (95.72%). The most common cause of injuries are falls (67.34%). In the primary dentition, the most common type of injury is extrusive luxation (38.23%) and in the permanent dentition, it is fracture of enamel,dentin without pulpal involvement (50.5%). From 147 patients, only 82 presented to our clinic within 1 h and 10 days after the injury time. It reveals that there is a need to inform the public of what they should do in cases of dental trauma, and how important it is to contact a dentist immediately. [source] Prevalence of dental trauma in 5,6- and 12,14-year-old boys in Riyadh, Saudi ArabiaDENTAL TRAUMATOLOGY, Issue 4 2001Ibrahim Al-Majed Abstract , This study involved 354 boys aged 5,6 years and 862 boys aged 12,14 years, attending 40 schools in Riyadh. All children were examined at school by a single dental examiner, using criteria similar to those employed in the survey of children's dental health in the United Kingdom. The prevalence of dental trauma in 354 Saudi boys aged 5,6 years was 33%. The most common type of dental trauma was fracture of enamel (71%) followed by loss of tooth due to trauma (13%), fracture into enamel and dentine (7%), discolouration (5%), pulp involvement (4%). No relationship between the degree of overjet and the occurrence of dental trauma in the primary dentition was observed. The prevalence of dental trauma in 862 12,14-year-old boys was 34%. The commonest dental trauma was fracture of enamel (74%) followed by fracture into enamel and dentine (15%), fracture into enamel-dentine and pulp (5%), loss of tooth due to trauma (3%), and discolouration (0.4%). A significant relationship (P=0.02) between the increased overjet (, 6 mm) and the occurrence of dental trauma in the permanent dentition was reported. The present study found no evidence of dental care provided for traumatised primary incisors in 5,6-year-old boys. The treatment of dental trauma in 12,14-year-old boys was negligible (2.4%). The present Saudi Arabian study showed higher prevalence of dental trauma in 5,6- and 12,14-year-old boys than the reported results of the United Kingdom Children's Dental Health Survey of the same age groups. [source] The braincase of the chondrichthyan Doliodus from the Lower Devonian Campbellton Formation of New Brunswick, CanadaACTA ZOOLOGICA, Issue 2009John Maisey Abstract The braincase of the late Lower Devonian (Emsian) chondrichthyan Doliodus is described for the first time. Its postorbital process is extended ventrally and probably enclosed part of the infraorbital sensory canal, as in some placoderms. Doliodus has a shark-like dentition, but its upper anterior tooth files were supported by the internasal cartilage of the braincase, not by the palatoquadrates. Modern selachian jaws and dentitions are not representative of primitive crown-group gnathostomes because they display a mixture of conserved and derived character states. Separation of the palatoquadrates by the internasal cartilage is probably a primitive condition for crown-group gnathostomes. Continuity of the upper dental arcade across the ethmoid region may represent a synapomorphy of chondrichthyans and some acanthodians (the condition is not found in placoderms or osteichthyans). Exclusion of the arcade from the ethmoid region is probably apomorphic within elasmobranchs. Doliodus has curious bar-like, paired subcranial ridges ending posteriorly at the hyomandibular articulation. These superficially resemble visceral arch infrapharyngohyals fused to the floor of the braincase, adding circumstantial palaeontological support to the old proposal that parts of visceral arches may be incorporated into the gnathostome braincase, although it seems more plausible that they formed in the lateral margins of the embryonic parachordal or hypotic lamina. [source] The dentition of Goodrichthys, a Carboniferous ctenacanthiform shark from ScotlandACTA ZOOLOGICA, Issue 2009Michal Ginter Abstract Study of three sets of chondrichthyan teeth from the Mississippian (Viséan) of Glencartholm, Scotland, namely the dentition of the holotype of a ctenacanthiform shark Goodrichthys eskdalensis, the dentition of a recently found, yet undescribed shark (NMS 2000.14.2), and a group of isolated teeth probably found in a nodule, tentatively suggests that all of them represent the same species. The combined characters of these teeth show that the dentition of Goodrichthys was moderately heterodont, of a cladodont design, in which larger teeth may have had three, and smaller ones only two, lateral cusps on each side of a prominent, coarsely cristated median cusp. The base is similar to that of Cladodus and Famennian representatives of Ctenacanthus, with a prominent, undivided basolabial shelf and an almost straight orolingual ridge. [source] A new specimen of Helicoprion Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and functionACTA ZOOLOGICA, Issue 2009O. 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] Phylogenetic analysis of the pearlfish tribe Carapini (Pisces: Carapidae)ACTA ZOOLOGICA, Issue 4 2000E. Parmentier Abstract Fishes of the tribe Carapini (Encheliophis and Carapus) share a noteworthy peculiarity: they shelter in holothurian echinoderms or bivalve hosts. Some species are considered parasitic, others commensal. This study focuses on the phylogeny of the tribe, using two other Carapidae species as an outgroup (Snyderidia canina and Onuxodon fowleri). Insofar as possible, the selected anatomical and behavioural characters where chosen in an ecomorphological perspective, as features that could be responses to various lifestyle-related constraints. Our character selection also took into account the fact that some features are (presumably) linked. Such features were grouped together as a single trait to avoid their overvaluation. This methodology enabled commensals to be separated from parasites, the former belonging to Carapus and the latter to Encheliophis. Carapus species reflect in their morphology the constraints imposed by a diet of hard, mobile, elusive prey, showing predator-type features: a strong dentition, a wide mouth opening, a robust food intake apparatus. On the other hand, the endoparasitic Encheliophis species show a generally weaker buccal apparatus and narrow mouth opening, in relation to the different constraints of their lifestyle where the diet constraints are less pronounced: they eat body parts of their host. Changes in both generic diagnoses are proposed and three species are transferred from Encheliophis to Carapus. [source] Teaching received in caries prevention and perceived need for Best Practice Guidelines among recent graduates in FinlandEUROPEAN JOURNAL OF DENTAL EDUCATION, Issue 1 2004Miira M. Vehkalahti The present study evaluated teaching that recent graduates in Finland had received in caries prevention and their perceived need for updated Best Practice Guidelines. A two-page questionnaire was mailed to all dentists in Finland who had graduated from 1995 to 1998 (n = 390). After one reminder, the response rate was 46%. The closed questions covered teaching in 14 caries-preventive methods and its suggestions as to when and on whom to apply such methods. Each dentist's own opinion on the three most important methods for caries prevention in patients with various types of dentition was sought in open questions. The respondents reported that at dental school, on average 12.5 (SD = 2.4) of 14 aspects of caries prevention were covered in theoretical teaching, 5.5 (SD = 3.8) in demonstrations and 8.5 (SD = 3.0) in clinical training. The top four methods teaching suggested for every patient were toothbrushing (100%), use of fluoridated toothpaste (99%), interdental cleaning (98%), and use of xylitol (97%); followed by fluoride varnish (77%) and fissure sealants (54%). The three caries-preventive methods the respondents felt to be most useful were the same for all types of dentitions, in order of importance: (i) toothbrushing and use of fluoridated toothpaste, (ii) supplementary use of fluorides at home and (iii) healthy dietary habits, in particular, avoidance of sucrose. As regards clinical work, such teaching had served the respondents' real-life needs in patients' caries prevention either extremely (44%) or moderately (54%) well; 91% said, however, that they would benefit from nationwide Best Practice Guidelines. In conclusion, the recent graduates' emphasis on patient-active methods in caries prevention may indicate a change in the current policy favouring patient-passive methods. [source] Development of heterodont dentition in house shrew (Suncus murinus)EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2007Atsushi Yamanaka Mammalian heterodont dentition comprises incisors, canines, premolars, and molars. Although there has been intensive research, the patterning of these specific tooth types has not yet been elucidated. In order for the gene expression data to be linked with tooth type determination, it is first necessary to determine precisely the incisor-, canine-, premolar-, and molar-forming regions in the jaw primordia. To accomplish this, we studied dentition development in the house shrew (Suncus murinus), which has retained all the tooth types, using three-dimensional reconstructions from serial histological sections and the Sonic hedgehog (Shh) expression patterns. Before the appearance of morphological signs of odontogenesis, Shh expression localized to the presumptive tooth-forming regions, in which the mesial and distal expression domains corresponded to the incisor- and premolar-forming regions, respectively. The upper incisor region was found to extend across the boundary between the frontonasal and the maxillary processes. The canine-forming regions later appeared in the intermediate portions of the maxillary and the mandibular processes. The molar-forming regions later appeared distal to the initially demarcated tooth-forming regions by secondary extension of the distal ends. The demarcation visualized by the Shh expression pattern in the jaw primordia of the house shrew probably represents the basic developmental pattern of mammalian heterodont dentition. [source] The taming of the shrew milk teethEVOLUTION AND DEVELOPMENT, Issue 4 2008Elina Järvinen SUMMARY A characteristic feature of mammalian dentition is the evolutionary reduction of tooth number and replacement. Because mice do not replace teeth, here we used Sorex araneus, the common shrew, as a model to investigate the loss of tooth replacement. Historically, shrews have been reported to initiate the development of several, milk or deciduous teeth but these soon become rudimentary and only the replacement teeth erupt. Shrews thus offer a living example of a derived mammalian pattern where the deciduous tooth development is being suppressed. Based on histological and gene expression analyses of serial sections, we suggest that S. araneus has discernible tooth replacement only in the premolar 4 (P4) position. Both generations of teeth express Shh in the enamel knot and in the inner enamel epithelium. Nevertheless, the deciduous P4 (dP4) is reduced in size during embryogenesis and is eventually lost without becoming functional. Analysis of growth shows that P4 replaces the dP4 in a "double-wedge" pattern indicative of competitive replacement where the suppression of the deciduous tooth coincides with the initiation of its replacement. Because activator,inhibitor mechanisms have been implicated in adjacent mouse molars and in transgenic mice with continuous tooth budding, we suggest that evolutionary suppression of deciduous teeth may involve early activation of replacement teeth, which in turn begin to suppress their deciduous predecessors. [source] Holes in the head: Evolutionary interpretations of the paranasal sinuses in catarrhinesEVOLUTIONARY ANTHROPOLOGY, Issue 6 2004Todd C. Rae Everyone who has ever experienced a head cold is familiar with the paranasal sinuses, the bony hollows above and beside the nasal cavity that contribute, sometimes painfully, to upper respiratory tract disorders. These internal cranial structures have a wide distribution among eutherian mammals and archosaurs.1, 2 Sinuses have languished somewhat in the shadow of their better known and more accessible morphological cousins (dentition, postcrania), but new imaging techniques, growth studies, and explicit phylogenetic evaluation3 are beginning to fill in the gaps in our knowledge of the evolution of these enigmatic spaces in primates and promise to yield insights into the evolution of the facial skeleton. [source] Understanding the ,epidemic' of complete tooth loss among older New ZealandersGERODONTOLOGY, Issue 2 2010Philip V. Sussex doi:10.1111/j.1741-2358.2009.00306.x Understanding the ,epidemic' of complete tooth loss among older New Zealanders Objective:, The aim of this study was to obtain a deeper understanding of the social factors driving New Zealand's historic ,epidemic of edentulism' and how they operated. Method:, In-depth, semi-structured interviews with 31 older New Zealanders were analysed using applied grounded theory. Results:, Universal factors present in the data were: (a) the way in which New Zealand society accepted and indeed encouraged edentulism without stigma for those who had a ,sub-optimal' natural dentition; (b) how the predominant patterns of dental care utilisation (symptomatic and extraction-based) were often strongly influenced by economic and social disadvantage; and (c) the way in which lay and professional worldviews relating to ,calcium theory' and dental caries were fundamental in decisions relating to the transition to edentulism. Major influences were rural isolation, the importance of professional authority and how patient-initiated transitions to edentulism were ultimately facilitated by an accommodating profession. Conclusion:, The combined effects of geography, economics, the dental care system and the professional culture of the day, in the context of contemporary (flawed) understandings of oral disease, appear to have been the key drivers. These were supported (in turn) by a widespread acceptance by the profession and society alike of the extraction/denture philosophy in dealing with oral disease. [source] Dental status and dental caries in 85-year-old DanesGERODONTOLOGY, Issue 1 2007Lene Vilstrup Objectives:, This study reports findings on the dental status and the prevalence of dental caries among a group of 85-year-old Danes from the Glostrup 1914 Cohort, Denmark. The purpose of the study was to analyse whether caries experience was related to number of teeth and to indicators of functional ability and cognitive function. Methods:, A total of 191 individuals (78 men and 113 women) participated in a cross-sectional population study conducted in 2000. Using mobile dental equipment, a clinical oral examination and an interview were administered to all participants in their homes. Functional ability was measured by the Mob-H scale and cognitive function was assessed by the Mini-Mental State Examination. Results:, Fifty-nine per cent of the participants had their own natural teeth and for the dentate participants, the mean number of teeth was 13 (range 1,27). A high prevalence of active caries on coronal and root surfaces was observed. Older adults with few natural teeth had a higher prevalence of active coronal and root caries and a higher unmet treatment need than older adults with many teeth. Further, the study showed that 85-year-old persons with reduced functional ability and cognitive impairment tended to have more active caries than 85-year-olds with no impairment. Conclusions:, A substantial proportion of 85-year-old individuals had retained a natural dentition; however, active dental caries is a problem of concern among the most elderly. [source] Taurodontism: a review of the condition and endodontic treatment challengesINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2008H. Jafarzadeh Abstract Taurodontism can be defined as a change in tooth shape caused by the failure of Hertwig's epithelial sheath diaphragm to invaginate at the proper horizontal level. An enlarged pulp chamber, apical displacement of the pulpal floor, and no constriction at the level of the cementoenamel junction are the characteristic features. Although permanent molar teeth are most commonly affected, this change can also be seen in both the permanent and deciduous dentition, unilaterally or bilaterally, and in any combination of teeth or quadrants. Whilst it appears most frequently as an isolated anomaly, its association with several syndromes and abnormalities has also been reported. The literature on taurodontism in the context of endodontics up to March 2007 was reviewed using PubMed, MEDLINE and Cumulative Index to Nursing & Allied Health Literature. Despite the clinical challenges in endodontic therapy, taurodontism has received little attention from clinicians. In performing root canal treatment on such teeth, one should appreciate the complexity of the root canal system, canal obliteration and configuration, and the potential for additional root canal systems. Careful exploration of the grooves between all orifices particularly with magnification, use of ultrasonic irrigation; and a modified filling technique are of particular use. [source] A vicious cycle in the oral health status of schoolchildren in a primary school in rural CambodiaINTERNATIONAL JOURNAL OF DENTAL HYGIENE, Issue 3 2007Emiko Koito Shidara Abstract, Objective:, To investigate the oral health status and the risk factors contributing to dental caries and gum disease of schoolchildren in Cambodia. Methods:, A cross-sectional survey was conducted in a primary school in the Puok District, Siem Reap Province of Cambodia. An oral examination and self-reported questionnaire were used to evaluate oral health status of schoolchildren, ranging in age from 6,16. Of the 512 children that were enrolled in first through sixth grade at the primary school, 332 children (62.8%) participated. Results:, Of the schoolchildren that were involved in this study, the prevalence of dental caries in permanent dentition was 53.5% and gum disease was present in 46.2%. Among the participants 80% had plaque, 68.6% suffered from tooth pain and only 44.2% of the schoolchildren owned their own toothbrush. There was an association between the schoolchildren that suffered from tooth pain and those that had dental caries (P < 0.03). Plaque was related to dental caries in permanent dentition (P < 0.003), calculus (P < 0.0001) and gum disease (P < 0.0001) and was linked to the schoolchildren who did not own a toothbrush (P < 0.03) and who suffered from tooth pain (P < 0.03). Conclusion:, The following sequence of events may result in a vicious cycle in the oral healthcare of schoolchildren in rural Cambodia: the lack of a personal toothbrush leads to plaque buildup, which may increase the incidence of dental caries, which has been linked to tooth pain and gum disease. Ultimately, this poor oral healthcare impacts an individual's quality of life and can lead to more serious health issues later in life. [source] | ||||||||||||||||||||||||||||||||||||||||