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PubMed2004

The use of an individual jig in measuring tooth length changes.

The parallel periapical radiographic technique hides several problems that might affect the image seen on the film. To overcome these problems a special jig with an external wire attached to the tooth surface and parallel to its long axis was suggested. This study examines the accuracy of using an external object for measuring root length differences due to angular changes between the tooth and the film. The rule of three was used for all calculations as a compensating formula. A human central incisor was placed in a special jig. Two different wire lengths (11.8 +/- 0.1 mm and 16 +/- 0.1 mm) were attached to the tooth in six different ways. The tooth was radiographed at four different film to tooth angulations. The tooth and wire lengths were measured on the model itself and directly on the scanned film on a computer monitor. The results reveal that a wire, placed nine mm from the crown and parallel to the long axis of the tooth was the best jig for accurately measuring tooth length changes. Neither palatal nor buccal metal wires, intimately attached to the crown of the tooth, can serve as a tool to measure tooth length changes. The study could not find a way to skip the need for a cephalometric radiograph to verify the parallelism between the wire and the long axis of the tooth for this matter.

Cephalometry↗

PubMed2007

Effects of human relaxin on orthodontic tooth movement and periodontal ligaments in rats.

INTRODUCTION: The rate-limiting step in orthodontic treatment is often the rapidity with which teeth move. Using biological agents to modify the rate of tooth movement has been shown to be effective in animals. Relaxin is a hormone present in both males and females. Its main action is to increase the turnover of fibrous connective tissues. Thus, relaxin might increase the amount and rate of tooth movement through its effect on the periodontal ligament (PDL). The purpose of this study was to measure the effect of relaxin on orthodontic tooth movement and PDL structures. METHODS: Bilateral orthodontic appliances designed to tip maxillary molars mesially with a force of 40 cN were placed in 96 rats. At day 0, the animals were randomized to either relaxin or vehicle treatment. Twelve rats in each group were killed at 2, 4, 7, and 9 days after appliance activation. Cephalograms were taken at appliance placement and when the rats were killed. Tooth movement was measured cephalometrically in relation to palatal implants. Fractal analysis and visual analog scale assessments were used to evaluate the effect of relaxin on PDL fiber organization at the tension sites in histologic sections. The in-vitro testing for PDL mechanical strength and tooth mobility was performed by using tissue from an additional 20 rats that had previously received the same relaxin or vehicle treatments for 1 or 3 days (n = 5). RESULTS: Both groups had statistically significant tooth movement as functions of time. However, relaxin did not stimulate significantly greater or more rapid tooth movement. Fractal and visual analog scale analyses implied that relaxin reduced PDL fiber organization. In-vitro mechanical testing and tooth mobility assessments indicated that the PDL of the mandibular incisors in the relaxin-treated rats had reduced yield load, strain, and stiffness. Moreover, the range of tooth mobility of the maxillary first molars increased to 130% to 170%, over vehicle-treated rats at day 1. CONCLUSIONS: Human relaxin does not accelerate orthodontic tooth movement in rats; it can reduce the level of PDL organization, reduce PDL mechanical strength, and increase tooth mobility at early time points.

Animals↗

PubMed2003

Tooth color measurement using Chroma Meter: techniques, advantages, and disadvantages.

UNLABELLED: Tooth whitening has become a popular and routine dental procedure, and its efficacy and safety have been well documented. However, the measurement of tooth color, particularly in the evaluation of the efficacy of a system intended to enhance tooth whiteness, remains a challenge. One of the instruments used for assessing tooth color in clinical whitening studies is the Minolta Chroma Meter CR-321 (Minolta Corporation USA, Ramsey, NJ, USA). This article describes the instrument and discusses various measuring procedures and the Chroma Meter's advantages, limitations, and disadvantages. The available information indicates that, although Minolta Chroma Meter CR-321 provides quantitative and objective measurements of tooth color, it can be tedious to use with a custom alignment device. The Chroma Meter data are inconsistent with the commonly used visual instruments such as Vitapan Classical Shade Guide (Vita Zahnfabrik, Bad Säckingen, Germany), although in many cases the general trends are similar. It is also questionable whether the small area measured adequately represents the color of the whole tooth. A more critical challenge is the lack of methods for interpreting the Chroma Meter data regarding tooth color change in studies evaluating the efficacy of whitening systems. Consequently, at present the Chroma Meter data alone do not appear to be adequate for determining tooth color change in whitening research, although the quantitative measurements may be useful as supplemental or supportive data. Research is needed to develop and improve the instrument and technique for quantitative measurement of tooth color and interpretation of the data for evaluating tooth color change. CLINICAL SIGNIFICANCE: This paper will help readers to understand the advantages and limitations of the Minolta Chroma Meter used for evaluating the efficacy of tooth-whitening systems so that proper judgment can be made in the interpretation of the results of clinical studies.

Color↗

PubMed2000

Tooth loss and need for extractions in American Indian and Alaska Native dental patients.

OBJECTIVE: This article reports results of the 1991 Indian Health Service Patient Oral Health Survey in the areas of tooth loss and need for tooth extraction. METHODS: The survey examined a sample of American Indian and Alaska Native dental patients. Tooth loss and need for tooth extraction are explored for a total of 12,349 individuals aged 18 years and older. RESULTS: Complete tooth loss in patients aged 35 years and older was 11 percent; in patients aged 65 years and older, it was 42 percent. The mean number of remaining teeth in dentate patients aged 35 years and older was 20.7; the mean number of remaining teeth decreased in each older age group. Partial and complete tooth loss were more severe in diabetic patients. In 35- to 44-year-old patients, only 20 percent had not lost at least one permanent tooth. The prevalence of tooth loss differs by geographic region. The percentage of dental patients with 20 or more teeth increased between 1984 and 1991. CONCLUSION: Tooth loss remains a substantial problem in American Indian and Alaska Native adult dental patients. This article presents results of an Indian Health Service (IHS) oral health survey conducted in 1991 of the American Indian and Alaska Native (Native American) population with respect to tooth loss. Limited comparisons of tooth loss observed in the 1991 patient survey are made to the 1984 patient survey.

Adolescent↗

PubMed2004

Bioengineered teeth from cultured rat tooth bud cells.

The recent bioengineering of complex tooth structures from pig tooth bud tissues suggests the potential for the regeneration of mammalian dental tissues. We have improved tooth bioengineering methods by comparing the utility of cultured rat tooth bud cells obtained from three- to seven-day post-natal (dpn) rats for tooth-tissue-engineering applications. Cell-seeded biodegradable scaffolds were grown in the omenta of adult rat hosts for 12 wks, then harvested. Analyses of 12-week implant tissues demonstrated that dissociated 4-dpn rat tooth bud cells seeded for 1 hr onto PGA or PLGA scaffolds generated bioengineered tooth tissues most reliably. We conclude that tooth-tissue-engineering methods can be used to generate both pig and rat tooth tissues. Furthermore, our ability to bioengineer tooth structures from cultured tooth bud cells suggests that dental epithelial and mesenchymal stem cells can be maintained in vitro for at least 6 days.

Absorbable Implants↗

PubMed2003

[Influence of bone remodeling in extraction sites on tooth movement].

OBJECTIVE: To investigate the influence of bone remodeling in extraction sites and orthodontic forces on tooth movement with the aim of providing a basis for selecting optimal orthodontic forces, time of tooth movement and reducing the time for tooth moving into extraction sites. METHODS: Extraction of upper first molars were performed on 36 male Sprague-Dawley rats which were divided equally into 3 groups. A method for quantification of orthodontic tooth movement in the rats was presented. Orthodontic appliance was placed at different time after tooth extraction. Different forces were used to move the maxillary second molars mesially into the extraction spaces. X-ray was taken before appliance activation and after 1, 3, 5, 7, 10, 14 days since appliance activation. Tooth movement was measured cephalometrically by Imagine Analysis Technique, adjusting for magnification by using the known digitized length of the broach. RESULTS: 1. The tooth on the recent extraction side moved faster than that on the healed side. 2. Tooth movement at all time points on the 0.30 N curve differed from those on the higher force curves (P < 0.01), either moving into recent extraction sites or healing sites. Comparison between 0.60 N and 1.36 N indicated that mesial molar movement did not differ from each other after day 5. 3. The classical tooth movement curve had three parts that represent distinctly different processes: early movement; delay; later movement. CONCLUSION: 1. The tooth on the recent extraction side moved faster than that on the healed side. 2. Moderate force maybe was the optimal orthodontic force. It could be overloaded, but resulted in no further enhancement of tooth movement.

Animals↗

PubMed2003

[The cellular and molecular bases of "tooth framing"].

Progress in molecular biology in recent years has enormously increased interest in tooth generation. The enamel knot has been discovered, in consequence. This is a transient structure acting as molecular signaling center, responsible for controlling cusp formation, stimulating growth of surrounding epithelium, and generating new knots or their disappearance through apoptosis. Both tooth development and enamel knots are regulated by a cascade of gene activity where Fgf4, Shh, BMP4, Lef1 and p21 are the prime movers of the processes. Homeobox genes (Msx, Dlx) are the orchestrators of the framing and a series of proteins (adhesion molecules, extracellular matrix components) are the executors of "tooth framing". An important concept has emerged from developmental biology through the identification of the basic mechanisms involved in tooth development: the molecular basis of structure framing shares common rules. Thus similar genetic programs are involved in body structure generation (limb bud, tooth, branching morphogenesis). A deeper understanding of developmental rules regulating tooth formation will make it possible in the near future: a) to modify in vivo homeobox gene expression and restore tooth generation hampered by tooth agenesia due to homeobox gene deregulation; b) to induce complete tooth formation, in case of tooth loss due to trauma or diseases, through implantation in the patient's oral cavity of a synthetic ball containing morphogens and growth factors to stimulate, in the right spatio-temporal sequence, the entire tooth genetic cascade. These concepts will certainly enforce cultural and practical interaction between biology and dentistry.

Animals↗

PubMed2005

Tooth wear in the elderly population in South East Local Government area in Ibadan, Nigeria.

It is the aim of this study to determine the pattern and degree of tooth wear in the elderly population in the South East Local Government Area in Ibadan. The study was carried out on 690 elderly individuals who were 65 years old and above, living in various wards in South East Local Government Area, in Ibadan. A multistage sampling technique was used to select elderly individuals for the study. Two interviewers, 2-record clerks and 2 examiners were trained for the study and the examiners were calibrated. The index of Eccles J.D was used to determine the severity of tooth wear. The results highlight the high prevalence of tooth wear, mainly attrition in the elderly in this local government area. Six hundred and forty (92.8%) of the elderly had tooth wear. Of these 58.59% were males and 41.41% females. Attrition was observed in 618 (89.6%) elderly individuals. The mandible exhibited a higher prevalence of tooth wear than the maxilla and was statistically significant. Severe tooth wear was observed in only 5.74% of the teeth whilst moderate and mild tooth wear were observed in 26.91% and 30.88% respectively. Unlike the Western European countries, attrition being the most common type of tooth wear in these elderly individuals suggests that the aetiological factors responsible for tooth wear are different. Common habits such as crushing of bones and chewing of sticks for routine oral hygiene care could be contributing factors to tooth wear in this environment.

Aged↗

PubMed1995

Teeth and tooth nerves.

(1) Although our knowledge on teeth and tooth nerves has increased substantially during the past 25 years, several important issues remain to be fully elucidated. As a result of the work now going on at many laboratories over the world, we can expect exciting new findings and major break-throughs in these and other areas in a near future. (2) Dentin-like and enamel-like hard tissues evolved as components of the exoskeletal bony armor of early vertebrates, 500 million years ago, long before the first appearance of teeth. It is possible that teeth developed from tubercles (odontodes) in the bony armor. The presence of a canal system in the bony plates, of tubular dentin, of external pores in the enamel layer and of a link to the lateral line system promoted hypotheses that the bony plates and tooth precursors may have had a sensory function. The evolution of an efficient brain, of a head with paired sense organs and of toothed jaws concurred with a shift from a sessile filter-feeding life to active prey hunting. (3) The wide spectrum of feeding behaviors exhibited by modern vertebrates is reflected by a variety of dentition types. While the teeth are continuously renewed in toothed non-mammalian vertebrates, tooth turnover is highly restricted in mammals. As a rule, one set of primary teeth is replaced by one set of permanent teeth. Since teeth are richly innervated, the turnover necessitates a local neural plasticity. Another factor calling for a local plasticity is the relatively frequent occurrence of age-related and pathological dental changes. (4) Tooth development is initiated through interactions between the oral epithelium and underlying neural crest-derived mesenchymal cells. The interactions are mediated by cell surface molecules, extracellular matrix molecules and soluble molecules. The possibility that the initiating events might involve a neural component has been much discussed. With respect to mammals, the experimental evidence available does not support this hypothesis. In the teleost Tilapia mariae, on the other hand, tooth germ formation is interrupted, and tooth turnover ceases after local denervation. (5) Prospective dental nerves enter the jaws well before onset of tooth development. When a dental lamina has formed, a plexus of nerve branches is seen in the subepithelial mesenchyme. Shortly thereafter, specific branches to individual tooth primordia can be distinguished. In bud stage tooth germs, axon terminals surround the condensed mesenchyme and in cap stage primordia axons grow into the dental follicle.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2005

Neutralizing effects of an anti-vascular endothelial growth factor antibody on tooth movement.

Our recent studies demonstrated that local administration of recombinant human vascular endothelial growth factor (rhVEGF) during experimental tooth movement enhanced the number of osteoclasts and the rate of tooth movement. The purpose of this study was to examine the effect of anti-VEGF polyclonal antibody on osteoclastic differentiation, the amount of tooth movement, and the degree of tooth relapse in 30-day-old mice. First, these mice were subjected to various doses of anti-VEGF polyclonal antibody, with tooth movement for three days. In the next study, daily injections of 10-microg antibody were administered for 18 days during the experimental tooth movement. The amount of tooth movement was measured as in our previous study. Furthermore, in the third study, we administered daily injection of 10-microg antibody and measured tooth relapse after the experimental tooth movement for 45 days. The osteoclasts number in 10- and 50-microg antibody two-time injection group was significantly smaller than that in the controls (P < .05). The number of osteoclasts was decreased more substantially by daily injection of 10-microg antibody, showing more significant differences from the controls (P < .01). The amount of tooth movement was significantly less in the experimental group than in the controls on days 15 and 18 (P < .05). Furthermore, the amount of relapse in the experimental group was significantly less than that in the controls on days 9 and 11 after removal of the appliance (P < .05). These results show that the treatment of anti-VEGF polyclonal antibody markedly reduced the osteoclasts number and inhibited the amount of tooth movement and relapse of moved teeth.

Animals↗

PubMed2002

Computer-based evaluation of gender identification and morphologic classification of tooth face and arch forms.

STATEMENT OF PROBLEM: In prosthodontics, sex-related differences in tooth forms are assumed, and optimal esthetics is further assumed to be achieved only if the face, arch, and tooth forms are in harmony. However, there is no universally accepted rule or mathematical method to define these morphologic features. PURPOSE: The purpose of this study was to evaluate whether anterior tooth from reflected gender and to question the hypothesis that there was a correlation among face, arch, and tooth forms on the basis of dentists' perceptions. MATERIALS AND METHODS: Photographic records including full face, dental arch, and anterior tooth images of 60 dental students were made by use of digital photography. A database was arranged as a questionnaire for evaluation by prosthodontists who were asked to define the sex and morphologic features of the subjects by examining stored images of the subjects. Thirteen prosthodontists, all with at least 10 years of experience, served as experts and performed these evaluations twice at 2-week intervals. Kappa statistic was used to measure intraobserver and interobserver agreement. RESULTS: The average correctly identified values in females and males were 53% and 58%, respectively. However, the proportions of females and males who were identified correctly and completely the same in both the first and second evaluations were 36% for females and 41% for males. According to the observations of the experts, face-to-arch form (54%) and face-to-tooth form (51%) correlations were higher than the tooth-to-arch form correlation. The overall correlation among face, arch, and tooth forms was 31%. The experts were in fair agreement in defining tooth forms. CONCLUSIONS: The results of gender identification of the subjects showed that the experts were unsuccessful in distinguishing the actual sex by the visual assessment of anterior tooth segment alone, with a fair agreement between 2 evaluation sessions. There were also significant interobserver and intraobserver differences in classifying face, arch, and especially tooth forms. Furthermore, the correlation among these forms was not highly defined.

Cephalometry↗

PubMed2004

Intra-oral pattern of tooth and periodontal bone loss between the age of 50 and 60 years. A longitudinal prospective study.

OBJECTIVE: In a 10-year prospective study we analyzed (i) the intra-oral pattern of and (ii) potential risk factors for tooth and periodontal bone loss in 50-year-old individuals. METHODS: A randomized subject sample of 50-year-old inhabitants in the County of Varmland, Sweden, was examined at baseline and after 10 years. Data from full-mouth clinical and radiographic examinations and questionnaire surveys of 309 (72%) of the individuals who were dentate at baseline were available for analysis. Non-parametric tests and binary logistic multiple regression models were used for statistical analysis of the data. RESULTS: 4.1% of the 7,101 teeth present at baseline, distributed among 39% of the subjects, were lost during the 10-year interval. The incidence of tooth loss was highest among mandibular molars (7.5%) and lowest among canines (1.8%). The relative risk (RR) for tooth loss for endodontically compromised teeth was 4.1 and for furcation-involved molars 2.4-6.5, depending on tooth position. Logistic regression analysis identified baseline alveolar bone level (ABL), endodontic conditions, CPITN score (Community Periodontal Index of Treatment Needs), tooth position, caries, and educational level as risk factors for tooth loss. The overall mean 10-year ABL change was -0.54 mm (S.E. 0.01). On a tooth level the ABL change varied between -0.35 mm (mandibular molars) and -0.79 mm (mandibular incisors). Smokers experienced a greater (20-131% depending on tooth type) mean bone loss than non-smokers. The logistic regression model revealed that tooth position, smoking, and probing pocket depth > or =4 mm were risk factors for bone loss of >1 mm. No pertinent differences were observed with respect to risk factors for ABL change in the subgroup of non-smokers compared to the results of the analysis based on the entire subject sample. CONCLUSION: Tooth loss was more common in the molar than in the anterior tooth regions, while periodontal bone loss had a random distribution in the dentition. The predominant risk factors identified with regard to further radiographic bone loss were "probing pocket depth > or =6 mm" and "smoking".

Alveolar Bone Loss↗

PubMed1999

The informativeness of attachment loss on tooth mortality.

BACKGROUND: In periodontal clinical trials, clinical attachment level measurements are commonly used as surrogates for tooth loss. Conclusions regarding treatment efficacy in these trials are valid if: 1) the surrogate is informative on tooth loss, and 2) the surrogate captures the effect of treatment on tooth loss. The goal of this study was to evaluate the first criterion: Are serial clinical attachment loss measurements informative on overall tooth mortality? METHODS: Young Norwegian men (aged 17 to 35) were first examined in 1969 (n=565) and followed for 26 years with examinations in 1971 (n=381), 1973 (n=292), 1975 (n=245), 1981 (n=228), 1988 (n=202), and 1995 (n=223). Several aspects of the serial attachment loss measurements were related to tooth mortality risk using statistical models that take into account the time-dependent changes of the clinical attachment loss measurements. RESULTS: The results provided evidence that moderate attachment losses were informative on tooth mortality. Both the lifetime cumulative attachment loss, as well as attachment loss since young adulthood, of > or = 2 mm or > or = 3 mm was informative on tooth mortality. Tooth mortality risk increased as the attachment loss increased; loss > or = 3 mm at the buccal or mesial site increased tooth mortality risk, by 91% (relative risk, 1.91; 95% confidence interval, 1.01-3.60) and 270% (RR, 3.70; 95% CI, 1.83-7.49), respectively. CONCLUSIONS: We concluded that clinical attachment loss was moderately informative on overall tooth mortality in this Norwegian population. Since this finding has now been demonstrated in 3 different populations, the focus of further research should be on evaluating whether the second criterion for a valid surrogate is satisfied: Does clinical attachment loss capture the effect of periodontal treatments on tooth loss?

Adolescent↗

PubMed2002

Sonography of the median nerve in Charcot-Marie-Tooth disease.

OBJECTIVE: The purpose of our study was to describe the features on high-frequency sonography of median nerves in patients with Charcot-Marie-Tooth disease and determine whether sonography can help in the detection and characterization of the disease in these patients. SUBJECTS AND METHODS: The median nerves of 24 patients with genetically proven Charcot-Marie-Tooth disease (12 patients with Charcot-Marie-Tooth disease type 1A, seven with Charcot-Marie-Tooth disease type 2, and five with Charcot-Marie-Tooth disease type X) were prospectively examined at the right mid forearm with a 12-5-MHz transducer. Image analysis for each patient included measurement of both the cross-sectional area and fascicular diameter of the nerve. Correlations then were made with genetic and electrophysiologic features and with findings in a control group of 50 subjects. RESULTS: Sonography was found to be a reliable means of detecting the nerve hypertrophy and the fascicular swelling occurring in patients with Charcot-Marie-Tooth disease. The 1A type of Charcot-Marie-Tooth disease could be distinguished sonographically by a larger nerve area and fascicular diameter than those observed in patients with the other types of disease (including Charcot-Marie-Tooth disease type 2 and X-linked type) and the control subjects. In patients with Charcot-Marie-Tooth disease and control subjects, linear regression analysis did not show a correlation between either the cross-sectional area or fascicular diameter of the nerve and the patient's height, body mass, sex, or electrophysiologic parameters. CONCLUSION: High-resolution sonography can be used to detect the hypertrophy of median nerves in patients with Charcot-Marie-Tooth disease. It can be helpful in defining the Charcot-Marie-Tooth type 1A on the basis of the larger nerve sizes and fascicular diameters than those occurring in patients with other types of the disease. In an affected kindred, sonography is promising as a screening tool for identifying individuals who should undergo genetic assessments.

Adolescent↗

PubMed2003

Developmental expression of Smad1-7 suggests critical function of TGF-beta/BMP signaling in regulating epithelial-mesenchymal interaction during tooth morphogenesis.

Members of the transforming growth factor-beta family (e.g. TGF-beta, BMP and activin) are critical regulators of tooth morphogenesis. The basic TGF-beta signaling engine consists of a receptor complex that activates Smads and a Smad-containing complex that controls transcription of the downstream target genes. Little is known about the expression of endogenous Smads during tooth morphogenesis. Using a cRNA probe or antibody which specifically recognizes the expression of each Smad molecule, we provide a comprehensive endogenous Smad expression analysis during tooth morphogenesis. BMP signaling is transmitted through Smad1 and 5 which are first expressed within the dental lamina and later expand into condensed dental mesenchyme at the bud stage. As tooth development advances into the cap and bell stage, BMP signaling Smads are strongly localized within the inner enamel epithelium (IEE) and cranial neural crest derived dental mesenchyme (DM), indicating their critical role in regulating epithelial-mesenchyme interaction during tooth morphogenesis. Smad2 and 3 are responsible for transmitting TGF-beta/activin signaling and show unique expression patterns during tooth morphogenesis. They are localized within the nuclei of both IEE and DM, suggesting that TGF-beta-activated Smads are critical for regulating tooth development. Smad4, the common Smad, is expressed in both dental epithelium and mesenchyme throughout all stages of tooth morphogenesis. The expression of inhibitory Smads (Smad6 and 7) largely overlaps with receptor regulated Smads, indicating that negative feedback on BMP/TGF-beta signaling is critical throughout all stages of tooth morphogenesis. Our results suggest that both receptor-regulated and inhibitory Smads are important regulators of tooth morphogenesis. The selective activation of Smad, as indicated by nucleartranslocation, may suggest selective activation of different members of the TGF-beta superfamily during tooth development.

Animals↗

PubMed2003

Predictors of bruxism, other oral parafunctions, and tooth wear over a 20-year follow-up period.

AIMS: To analyze predictors of bruxism, other oral parafunctions, and tooth wear in a group of subjects who had been examined 20 years earlier. METHODS: Originally, 402 randomly selected 7-, 11-, and 15-year-old subjects were examined clinically and by means of a questionnaire. Twenty years after the first examination, 94% of the original group could be traced, and 320 (85%) completed and returned the questionnaire. Of the oldest group, 100 (81%) also underwent a clinical examination focusing on occlusal factors and function and dysfunction of the masticatory system. For analyses of predictors of some oral parafunctions and tooth wear registered at the 20-year follow-up, logistic regression was used with recordings at the first examination as independent variables. RESULTS: Subjective reports in childhood of bruxism (defined as tooth clenching during daytime and/or tooth grinding at night), clenching only, grinding at night only, nail biting, and/or other parafunctions were predictors of the same oral parafunctions 20 years later. There were different predictors of the 2 components of bruxism, daytime tooth clenching and tooth grinding at night. Postnormal occlusion (Angle Class II malocclusion) and tooth wear in childhood predicted increased tooth wear in adulthood. Subjects with nonworking-side interference had less anterior tooth wear than those without such interference. CONCLUSION: Oral parafunctions in childhood may be a persistent trait in many subjects. Postnormal occlusion and tooth wear in childhood predicted increased anterior tooth wear 20 years later, whereas nonworking-side interference reduced the risk for such wear in 35-year-old subjects.

Adolescent↗

PubMed2004

In vitro evaluation of a novel 6% hydrogen peroxide tooth whitening product.

OBJECTIVES: The aims of this study were to evaluate the in vitro tooth whitening effects of a novel 6% hydrogen peroxide containing tooth whitener Xtra White (XW) on extrinsic stain and intrinsic tooth colour and the effects on enamel and dentine microhardness. In addition, to determine the levels of peroxide found in tooth pulp chambers after treatment with XW in vitro. METHODS: Extrinsic stain changes were determined by measuring colour changes of tea stained hydroxyapatite discs after treatment with water, placebo gel, XW or Colgate Simply White (CSW). Intrinsic tooth colour changes were determined by treating extracted human teeth in vitro with a placebo gel, XW or CSW for a simulated two weeks use and measuring colour differences with a chroma meter. Teeth treated with placebo gel and XW were cross-sectioned and the subsurface enamel and dentine was polished and the microhardness determined. The peroxide concentration found in extracted tooth pulp chambers was determined spectrophotometrically. RESULTS: XW gave significantly more extrinsic stain removal (p<0.0001) and an increase in tooth whiteness (p<0.05) than a placebo gel, but was not significantly different to CSW. There were no significant differences in subsurface enamel and dentine microhardness values for the placebo and XW treated teeth. The mean concentration of peroxide found in the tooth pulp chambers was 0.44 mM, which is over 3000 times below the concentration reported to cause pulpal enzyme damage. CONCLUSIONS: XW has been shown to be an effective tooth whitening product in vitro with support for its safety on subsurface enamel and dentine together with its safety on tooth pulp tissue.

Color↗

PubMedDate not supplied

Deciduous tooth chronology in the mandible of the domestic pig.

Fetuses of known age, collected from 20 days' gestation to term, were used to characterize the chronology of deciduous tooth development within the right mandible of swine. Tooth development was first observed at 32 days' embryonic development, with the differentiation of the deciduous third molar. Bud stages for the remaining deciduous teeth differentiated within the period of 32 to 38 days of embryonic development. Although the initial histological appearance of these teeth covered a short period of time, it was apparent that each tooth continued to develop at its own rate. The deciduous second incisor and first molar reached a stage of enamel formation by the 80th and 86th day of fetal development. This is a much later stage than previously recorded for beginning enamel formation. The stages of tooth development and enamel formation for each tooth are summarized. A previous report on the distribution of the dental lamina and deciduous tooth development in the mandible of the domestic pig combined with the information presented in this report on tooth chronology provide much of the information required for future studies using the domestic pig in dental research. A fetus observed at the 74th day of development demonstrated a tooth bud for the deciduous first premolar. The development of this tooth was followed closely throughout the remainder of fetal development with the cap stage representing its most definitive form at 110 days' development. The suggested deciduous origin for this tooth could result in a reevaluation of the nomenclature for the dental formula of swine.

Animals↗