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Dental arch space and permanent tooth size in the mixed dentition of a skeletal sample from the 14th to the 19th centuries and 3 contemporary samples.

Dental arch space and permanent tooth size in the mixed dentition were studied in 4 cohorts: (1) 48 skulls from the 14th to the 19th centuries from The Schreiner Collection in the Department of Anatomy, University of Oslo; (2) 39 boys and 34 girls of Sami origin born in the 1980s living in northern Norway; (3) 31 boys and 30 girls born in the 1960s living in southern Norway; and (4) 32 boys and 26 girls born in the 1980s living in the same part of southern Norway as the previous group. The sexes were unknown in the skeletal sample, and the groups were analyzed with the sexes pooled. The crown sizes of the permanent teeth in the mixed dentition of the Norwegian children who had lived between the 14th and the 19th centuries were smaller than those of contemporary children living in the same country. Probable reasons for this increase in tooth size include improved nutrition and reduced morbidity, because this study ruled out attrition as a major cause of the discrepancy in tooth size. The relative space (arch perimeter minus tooth size) in the group born in the 1960s deviated from that in the other 3 groups, indicating a greater degree of crowding in this group. The relative space in the skulls did not differ significantly from that in the groups born in the 1980s. This means that the improved caries situation during the last decades has changed the dental arch space in these populations. The irregularity index of the 4 mandibular permanent incisors was larger in the skulls than in the modern samples.

Analysis of Variance↗

Use of third molar transplantation for closure of the oroantral communication after tooth extraction: a report of 2 cases.

OBJECTIVE: This clinical report introduces a promising and unique method for the immediate closure of the oroantral communication (OAC) after tooth extraction: the use of the transplanted third molar with closed apices. STUDY DESIGN: In 2 adult patients, OAC caused by the extraction of an upper molar was immediately closed by using a transplanted third molar with complete root formation. After tooth extraction at the recipient site, OAC with perforated mucosa of the sinus floor was confirmed and the donor third molar was transferred to the prepared recipient socket. Endodontic therapy of the transplanted third molar began at 3 weeks after surgery, and prosthetic treatment was completed at 5 months after the operation. These 2 patients were carefully observed both clinically and radiographically. RESULTS: Closure of the OAC was successfully performed, and the transplanted teeth became fixed with the passage of time in these 2 patients. Root resorption did not occur, and good functional results were obtained without any complications. CONCLUSIONS: Tooth transplantation of a mature third molar for closure of the OAC is a simple and excellent method because the transplanted tooth not only closes the communication to the maxillary sinus, but it also satisfactorily functions at the recipient site during mastication, even in adult patients.

Adult↗

Further studies of a model for the etiology of anomalies of tooth number and size in humans.

A multifactorial model based on an underlying continuous distribution of tooth size, with thresholds determining hypodontia and supernumeraries, has been proposed [1]. Our aim is to investigate this model by comparing tooth morphology of affected patients and their first degree relatives with normal controls. An image analysis system [2] was used to measure teeth on study models of controls, patients with hypodontia of varying degrees and location, first-degree relatives of hypodontia index cases, and patients with supernumerary teeth in the maxillary incisor region. Mesio-distal crown size in hypodontia patients was smaller than controls, and this difference was significant for all tooth types. There was a general pattern: the more severe the hypodontia, the smaller the size of the tooth formed. Patients with supernumerary teeth had permanent maxillary central and lateral incisors and canines that were significantly larger in mesio-distal width than controls. The maxillary central incisors also differed in taper in supernumerary patients compared to controls. Hypodontia prevalence was higher in first-degree relatives (22%) of hypodontia index cases than in the general population (4.4%), and unaffected relatives had smaller teeth than controls. Thus, there were generalized and localized effects within the dentition, and these findings are compatible with the statistical expectations of the proposed multifactorial model.

Adult↗

Factors predisposing to postoperative complications related to wisdom tooth surgery among university students.

In a retrospective study among 550 Helsinki University students 20 to 30 years old, factors predisposing to postoperative complications from removal of lower jaw wisdom teeth were evaluated. Patient records and panoramic tomograms covering the period from 1990 to 1993 were examined; 50 patients (9.1%) had postoperative complications after removal of a wisdom tooth. The most common complications were alveolar osteitis (2.9%), postoperative infection (2.6%), postoperative bleeding (1.5%), and dysesthesia of the lower lip or tongue (1.1%). Factors associated with increased postoperative complications were mesiohorizontal position of the tooth, deep impaction of the tooth, and use of oral contraceptives. Before patients undergo surgery for removal of wisdom teeth, those who use oral contraceptives or have difficult tooth impactions should be informed about the increased possibility of postoperative complications.

Adult↗

Experimental and numerical determination of initial tooth mobility and material properties of the periodontal ligament in rat molar specimens.

The mechanical parameters of the periodontal ligament (PDL) in rat specimens were investigated in a combined experimental and numerical approach. Tooth mobility of the rat mandibular first molar was measured in vitro using a high precision experimental set-up. Finite element models (FEM) were developed, based on histological sections of the measured specimens, to simulate tooth mobility numerically under the same force systems as used in the experiment. Force/deflection curves from the measurements showed a significant non-linear behaviour of elastic stiffness of the PDL. A bilinear material parameter set was assumed to simulate tooth deflections. The numerical force/deflection curves were fitted to the experimental curves by repeatedly calculating theoretical tooth deflections and varying the parameters describing the non-linearity. Mean values of E1 = 0.15 MPa, E2 = 0.60 MPa and an ultimate strain of epsilon12 = 6.3 per cent were derived for the elastic behaviour of the rat PDL. Comparing fresh specimens and those frozen in a 0.9 per cent saline solution, differences between the measurements were significant. Using the agent, Periston, for freezing significantly reduced the deviation. The results indicated that strains in the PDL with a maximum of 14 per cent at the furcation were 10(4) times higher than strains in the bone, while the variability of stress values in both PDL and bone was not significant.

Alveolar Process↗

Traumatic self-inflicted bite with embedded tooth fragments in the lower lip.

An unusual case of traumatic self-inflicted bite of the lower lip in a 7-year-old girl is presented. As a result of the bite, due to a fall, four fragments of the right upper incisor tooth were embedded in the lower lip. The large tooth fragment appeared 18 days later, protruding through the skin of the lower lip. Radiographs confirmed the presence of these tooth pieces, which were removed under local anesthesia. Early diagnosis and surgical removal of the tooth fragments could prevent undesirable foreign-body reactions and scarring.

Accidental Falls↗

Exposure to oral uranyl nitrate delays tooth eruption and development.

The risk of oral exposure to uranium potentially involves the population at large. Tooth eruption and development are ongoing processes that begin during fetal development and continue until the age of 18 y. Since one of the mechanisms involved in tooth eruption is bone formation and it is well documented that uranium inhibits bone formation, the aim of the present work was to study the effect of oral administration of uranyl nitrate (UN) on tooth eruption and development. Wistar rats aged 1 and 7 d were orally administered a single dose of 90 mg kg(-1) body weight of uranyl nitrate. Two age matched groups received an equal volume of saline and served as controls. The animals were killed at 7 and 14 d of age, respectively. Mandibles were resected and processed to obtain bucco-lingual sections oriented at the level of the mesial root of the first mandibular molar, and histomorphometric studies were performed. Results showed that an acute high dose of uranyl nitrate delays both tooth eruption and development, probably due to its effect on target cells.

Animals↗

Tooth bud extraction and rubbing of herbs by traditional healers in Tanzania: prevalence, and sociological and environmental factors influencing the practices.

The practice by traditional healers in Tanzania of extracting tooth buds or of rubbing herbs on to the gingivae of young children to cure fevers and diarrhoea has been known for many years. The aim of this study was to determine the prevalence of these practices in different regions of Tanzania and to identify sociological and environmental factors influencing belief in their efficacy. A total of 1052 children were examined for missing primary teeth, or scars or wounds on the gingivae, resulting from tooth bud extraction. In addition, 268 parents of children who had received treatment from a traditional healer were interviewed to identify factors that led them to go to a traditional healer. The prevalence of tooth bud extraction in villages in which tooth bud extraction was first reported in the early 1980s was 0.5%, and in villages in which the practice was only recently reported it was 60%; the prevalence of rubbing herbs was 32% and 0.4%, respectively. Persistent fevers and diarrhoea were the major symptoms which led parents to go to a traditional healer. However, 60% of the parents had taken their child to a hospital before going to a healer; 72% of these had attended at least three times but only 5.5% reported that the treatment given in the hospital cured the condition. It is recommended that intensive health education on the causes, treatment and prevention of fevers and diarrhoea should be instituted, in conjunction with effective management of these conditions in hospital facilities.

Age Factors↗

Deviation from the Broadrick occlusal curve following posterior tooth loss.

Production of an appropriate occlusal curve for dentitions which have become deranged because of tooth loss, overeruption, tipping and drifting can present challenges for the dental technician. An earlier paper (J Oral Rehabil, 2005 32: 895-900.) demonstrates that the use of the Broadrick flag method for producing the occlusal curve is relatively accurate for most intact arches. This study demonstrates that when a posterior tooth has remained unopposed for 5 years or more positional changes, which cause deviation from the Broadrick curve, occur. The extent of the deviation may be extreme, potentially leading to difficulties in restoring a harmonious occlusal scheme. This study also demonstrates that the Broadrick curve may provide an accurate reproduction of the occlusal curve, even when the tooth forming the posterior determinant of the curve is tipped. A moderate degree of tipping of this tooth has little effect on the radius of the Broadrick curve.

Adult↗

An investigation of some factors associated with occlusal tooth wear in a selected high-wear sample.

The aim of the present study was to investigate the influence of some factors associated with occlusal tooth wear in a selected high-wear Swedish sample. The material comprised 59 persons having a mean age of 35 yr within the range 16-70 yr, the criteria for selection being a full or near-full complement of natural teeth, and the presence of definite clinical signs of occlusal wear. A dentition wear index, in addition to anterior, posterior, and arch subindices, was derived from a tooth-by-tooth evaluation of casts. Factors which were found to correlate significantly with increased occlusal wear were age, sex, self-perception of wear, number of teeth, and general health, as well as a number of variables from study-cast analysis. On the basis of the findings, not only is the multifactorial etiology of occlusal tooth wear a reality, but so, too, is the complex interdependence of these factors in the severity of wear.

Adolescent↗

Splints made of wire and composite: an investigation of lateral tooth mobility in vivo.

In 103 posttraumatic splints, later tooth mobility was measured with Periotest immediately before and after the routine splint removal. The splints were made of composite resin and an 0.017 X 0.025" orthodontic steel wire. 481 teeth were measured. A statistic evaluation revealed that the immobilisation effect did not exceed normal tooth firmness. Fixation to one neighbouring tooth had less effect than fixation to two. Adjacent tooth gaps reduced the effect. Splint extensions had no influence. With the use of the Periotest device, more than 50% of all teeth with a true mobility of 20 Periotest-units or more were detectable as mobile in spite of the fixed splint.

Adolescent↗

Clinical study of tooth shade lightening from dentist-supervised, patient-applied treatment with two 10% carbamide peroxide gels.

PURPOSE: Prescribed, patient-applied tooth lightening agents, or nightguard vital bleaching, typically utilizes a 10% carbamide peroxide agent applied during nocturnal hours. The purpose of this randomized double-blind study was to compare the amount of tooth color change in two groups of subjects using dentist-supervised, patient-applied 10% carbamide peroxide gel. MATERIALS AND METHODS: One group used Opalescence (Ultradent Products Inc., South Jordan, Utah) and the other NiteWhite Excel (Discus Dental, Inc., Los Angeles, California). Evaluation of tooth color for the six maxillary anterior teeth was done using a Vita shade guide at baseline, 1, 2, and 4 weeks. Subjects were instructed to apply the gel nocturnally using a custom-made soft tray 8 hours per day for 2 weeks. The 16 tabs of the shade guide were ranked according to value from darkest to lightest. The number (1-16) that correlated to the shade tab selected as the match for each tooth was the outcome variable. A Kruskal-Wallis one way analysis of variance on ranks was used. RESULTS: The test revealed no statistically significant difference between Opalescence and NiteWhite Excel for lightening the teeth (p = .807). The color change was still significant after 2 weeks without further bleaching activity. The baseline evaluation of the maxillary incisors and canines for all subjects, regardless of group, demonstrated a significant shade difference, with the canines being darker. This difference was not seen after 2 weeks of active bleaching or at the 4-week evaluation. CLINICAL SIGNIFICANCE: In this study comparing bleaching products, patients using Opalescence and NiteWhite Excel experienced a significant change in the color of their teeth relative to baseline values after 2 weeks of active treatment.

Adult↗

Tooth mortality in an adult rural population in Kenya.

This paper reports on the pattern of tooth loss in a random sample of 1131 adults aged from 15 to 65 years in a rural area of Kenya in which access to formal dental care is minimal. We found that the majority of the population retained most of their dentition in a functional state even up to the age of 65 years: In all age groups, more than 50% had at least 26 teeth present, and more than 90% had at least 16 teeth present. The prevalence of edentulousness was less than 0.3%. The principal cause of tooth loss in all age groups was caries, and this was true for all tooth-types except incisors, for which periodontal disease was the main cause of tooth loss. The cultural practice of removing lower central incisors was observed only in those over 40 years of age. More teeth were lost due to caries among women than among men, while the reverse was true for teeth lost due to periodontal diseases. In view of the fact that most people retain most of their teeth throughout life, it is suggested that the most appropriate strategies for dental health care in this population should be those promoting self care, rather than the introduction of a formal treatment-oriented approach provided by dentists.

Adolescent↗

Enamel knots as signaling centers linking tooth morphogenesis and odontoblast differentiation.

Odontoblasts differentiate from the cells of the dental papilla, and it has been well-established that their differentiation in developing teeth is induced by the dental epithelium. In experimental studies, no other mesenchymal cells have been shown to have the capacity to differentiate into odontoblasts, indicating that the dental papilla cells have been committed to odontoblast cell lineage during earlier developmental stages. We propose that the advancing differentiation within the odontoblast cell lineage is regulated by sequential epithelial signals. The first epithelial signals from the early oral ectoderm induce the odontogenic potential in the cranial neural crest cells. The next step in the determination of the odontogenic cell lineage is the development of the dental papilla from odontogenic mesenchyme. The formation of the dental papilla starts at the onset of the transition from the bud to the cap stage of tooth morphogenesis, and this is regulated by epithelial signals from the primary enamel knot. The primary enamel knot is a signaling center which forms at the tip of the epithelial tooth bud. It becomes fully developed and morphologically discernible in the cap-stage dental epithelium and expresses at least ten different signaling molecules belonging to the BMP, FGF, Hh, and Wnt families. In molar teeth, secondary enamel knots appear in the enamel epithelium at the sites of the future cusps. They also express several signaling molecules, and their formation precedes the folding and growth of the epithelium. The differentiation of odontoblasts always starts from the tips of the cusps, and therefore, it is conceivable that some of the signals expressed in the enamel knots may act as inducers of odontoblast differentiation. The functions of the different signals in enamel knots are not precisely known. We have shown that FGFs stimulate the proliferation of mesenchymal as well as epithelial cells, and they may also regulate the growth of the cusps. We have proposed that the enamel knot signals also have important roles, together with mesenchymal signals, in regulating the patterning of the cusps and hence the shape of the tooth crown. We suggest that the enamel knots are central regulators of tooth development, since they link cell differentiation to morphogenesis.

Animals↗

Prevalence of developmental defects of tooth enamel (DDE) in a pediatric hospital department of dentistry population (1).

This paper reports the first part of a three-part study of developmental defects of tooth enamel in a pediatric hospital population. The dental records of 8411 children who were discharged from the Department of Dentistry at the Royal Children's Hospital, Melbourne, Australia, between 1960 and 1987 were divided into an experimental group of 7518 patients comprising 25 groups of medical conditions, and a control group of 893 children who had dental disorders only. The aim of the study was to investigate the prevalence of hypoplastic and severe-opacity developmental defects of tooth enamel (DDE), in children and adolescents with major medical disorders, and to compare the prevalence with that in the control group of normal children. The prevalence figures obtained for the different medical conditions in this study agreed generally with those of other recent investigators. The high prevalence of defects found in Rubella Embryopathy children (81.8%) and in children with Prematurity alone (56.5%) is surprising, whereas the prevalence of 27.9% defects in Clefts of Lip and Palate and 26.4% defects in Clefts of Lip and Alveolus are probably well below the true prevalence. The control group prevalence was 9.3%, which is higher than in some other studies of 'normal' children. A pediatric hospital is a most useful source of fully documented medical and dental histories for the investigation of possible relationships between medical disorders and developmental defects of tooth enamel. The control group prevalence was 9.3%, which is higher than in some other studies of normal children. A pediatric hospital is a most useful source of fully documented medical and dental histories for the investigation of possible relationships between medical disorders and developmental defects of tooth enamel.

Adolescent↗

Alterations of tooth eruption and growth in pups suckling from diabetic dams.

Several studies have confirmed a decrease in the quality and quantity of milk of mothers with diabetes during lactation. However, it remains unclear how maternal diabetes affects the offspring specifically during lactation. The aim of this study was to evaluate body and mandibular growth and tooth eruption in pups suckling from diabetic dams. The study was performed on 13 Wistar rat pups that were born to dams that were subjected to experimental diabetes on the day of parturition. Body weight and body size were recorded regularly throughout the study. The experimental pups and a group of eight age-matched pups suckling from nondiabetic dams were killed at weaning. Both hemimandibles were excised and fixed. Right hemimandibles were radiographed to assess mandibular growth and tooth eruption. The left hemimandibles were processed to obtain buccolingually oriented sections at the level of the first mesial root of the first lower molar. Histologic and histomorphometric studies were performed. Results showed that body weight and body size were significantly lower in experimental animals at weaning compared with their age-matched controls. Smaller mandible size and reduced tooth eruption in experimental animals compared with controls were observed. The length, width, and bone volume of the developing alveolus were reduced in experimental animals compared with controls. The results obtained in this study allow the conclusion that suckling from diabetic dams results in reduced body, mandible size, and tooth eruption of the pups at weaning.

Animals↗

An overview of tooth discoloration: extrinsic, intrinsic and internalized stains.

The causes of tooth discoloration are varied and complex but are usually classified as being either intrinsic, extrinsic or internalized in nature. Dietary chromogens and other external elements deposit on the tooth surface or within the pellicle layer either directly or indirectly to form extrinsic discoloration. Stains within the dentine or intrinsic discoloration often results from systemic or pulpal origin, while internalized stains are the result of extrinsic stains entering the dentine via tooth defects such as cracks on the tooth surface.

Age Factors↗

The consequences of not replacing a missing posterior tooth.

BACKGROUND: Failure to replace a missing posterior tooth is assumed to result in host of adverse consequences, which include shifting of teeth and loss of alveolar bone support. METHODS: A retrospective longitudinal study (median follow-up period 6.9 years), using the radiographs of 111 patients who had an untreated bounded edentulous space, or BES, was conducted to determine the extent to which these adverse outcomes occurred. RESULTS: The majority of patients lost 1 millimeter or less of the distance between teeth adjacent to the space, extrusion of the opposing tooth was < or = 1 mm in 99 percent of the cases, and the amount of alveolar bone loss next to the adjacent teeth was < or = 1 mm in 83 percent of the cases. CONCLUSIONS: Within the follow-up time in this study, this group of patients did not exhibit the expected adverse consequences with either the frequency or severity generally assumed to be associated with nonreplacement of a single posterior tooth. CLINICAL IMPLICATIONS: These findings suggest that for the large majority of patients who experience a single-tooth posterior BES, immediate treatment may not be critical to the maintenance of arch stability. Instead, regular follow-up assessments to monitor change in stability and periodontal health may be warranted.

Adult↗