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PubMed1995

Convergence of afferents from superior sagittal sinus and tooth pulp on cells in the thalamus of the cat.

We have previously shown convergence of craniovascular and tooth pulp afferents in the cervical spinal cord of cats. This study looked for similar convergence in the thalamus. Fifty-four thalamic cells with input from tooth pulp, superior sagittal sinus, or both, were identified. Twenty-nine cells with tooth pulp and superior sagittal sinus input were located in the ventrobasal complex of the intralaminar nuclei. Most of these 29 cells were also excited by cooling the contralateral tooth pulp, and 21 had receptive fields on the contralateral face or forelimb. Twenty cells excited by stimulation of superior sagittal sinus, and not tooth pulp, were found in several nuclei. The 5 cells excited by stimulation of tooth pulp, but not sagittal sinus, were restricted to the ventrobasal complex. The data confirm convergence from sagittal sinus, tooth pulp, and skin in the thalamus of anaesthetized cats.

Afferent Pathways↗

PubMed2002

No association between incisal tooth wear and temporomandibular disorders.

STATEMENT OF PROBLEM: Incisal tooth wear may be a sign of long-term bruxing behavior. Bruxism is purported to be a risk factor for temporomandibular disorders (TMD). PURPOSE: The purpose of this clinic-based case-control study was to investigate whether the wear of anterior teeth is associated with TMD. MATERIAL AND METHODS: Two hundred eight TMD patients and 172 control subjects were selected for participation. After exclusion of subjects with more than 1 missing premolar or molar zone in opposite arches, as well as subjects with missing or severely restored anterior teeth, 154 TMD patients and 120 control subjects were included in the study (age 31.2 +/- 13.4 years; range 13 to 76 years). Anterior tooth wear was assessed on casts with a 0 to 5 scale. A multiple logistic regression analysis, controlling for the effects of age and gender, was performed to investigate the relationship between tooth wear and TMD. RESULTS: An odds ratio of 0.76 (95% confidence interval: 0.51 to 1.15) indicated that after adjusting for gender and age, the odds in favor of TMD decreased an estimated 24% for each additional unit of the mean tooth wear score. This result was not significant (P=.20). CONCLUSION: Within the limitations of this study, incisal tooth wear (assessed on dental casts) was not significantly associated with TMD when the influence of age and gender was controlled. Based on these findings, a clinically relevant risk for TMD from incisal tooth wear can be excluded. Hence, the presented evidence does not support the idea that treatment of incisal tooth wear is indicated to prevent TMD.

Adolescent↗

PubMed2002

Influence of different convergence angles and tooth preparation heights on the internal adaptation of Cerec crowns.

STATEMENT OF PROBLEM: Because of an imagining principle called active triangulation in the Cerec system, a shadow is cast distal to the illuminated objects. This distal shadow may be enlarged when the occlusal-cervical height of the prepared tooth is increased. Depth data of the shadow are unreliable, so the internal fit of Cerec crowns has been questioned. PURPOSE: This study evaluated the influence of different convergence angles and tooth preparation heights on the internal adaptation of Cerec crowns. MATERIAL AND METHODS: Tooth preparations were made on typodont teeth with different combinations of convergence angles and occlusal-cervical heights: Group I = 20 degrees angle, 6 mm height; Group II = 20 degrees angle, 4 mm height; Group III = 12 degrees angle, 6 mm height; and Group IV = 12 degrees angle, 4 mm height. Ten Cerec crowns were fabricated for each type of tooth preparation. Measurements of the internal fit were performed with the cement space replica technique and an image analysis system. Three-way analysis of variance was used to analyze the differences in cement space with different tooth preparations and the number of times that milling tools were used to prepare the Cerec crowns (P<.05). Multiple comparisons were made to evaluate differences between groups (P<.0083). RESULTS: Cerec crowns with a 12 degrees convergence angle demonstrated the best internal fit (cement space in Groups III and IV = 121 +/- 41 microm and 115 +/- 42 microm, respectively). The difference between the 2 convergence types was within the range of the scanning error (25 microm) produced by the Cerec camera. The number of times that milling tools were used had no significant effect on internal fit (P=.78). Tooth preparation height equal to or shorter than 6 mm occlusal-cervically with both 12 degrees and 20 degrees convergence angles also had no significant effect on internal fit (P>.0083). Cement space at distal walls (185 +/- 28 microm) was the thickest among all axial walls (P=.0001) and was twice as thick as that at the facial (90 +/- 14 microm) and palatal walls (92 +/- 15 microm). CONCLUSION: Within the limitations of this study, there was little difference in the internal fit of Cerec crowns prepared with convergence angles of 12 degrees and 20 degrees. Distal shadows influenced the thickness of the cement spaces, particularly at the distal walls. However, tooth preparations with an occlusal-cervical height not greater than 6 mm did not exaggerate the effect of the distal shadows.

Algorithms↗

PubMed2002

The lateral enamel lamina--component of tooth primordia in selected mammalian species.

The lateral enamel lamina (LEL) is a part of the enamel organ, which is probably not involved in tooth formation. It represents, besides the "stalk" of the tooth primordium, a second interconnection between enamel organ and oral epithelium or vestibular lamina. We detected the LEL in the sheep (Ovis aries), the dolphin (Stenella attenuata), and the vole (Microtus agrestis) by light microscopy and computer-aided three-dimensional reconstruction. The LEL could be found in cap to bell stage tooth primordia, most clearly in slowly developing tooth germs. LEL-like structures have been furthermore described or depicted in tooth germs of the mouse, the elk (Alces alces), the dugong (Dugong dugong), the elephant (Loxodonta africana), and the human. Probably it is a part of all mammalian tooth primordia that undergoes regression during morphogenesis of the enamel organ. As a reducing structure, it should be considered in studies of tooth development.

Animals↗

PubMed1995

Midkine (MK), a heparin-binding growth/differentiation factor, is regulated by retinoic acid and epithelial-mesenchymal interactions in the developing mouse tooth, and affects cell proliferation and morphogenesis.

Midkine (MK) is the first cloned gene in a new family of heparin-binding growth/differentiation factors involved in the regulation of growth and differentiation. We have analyzed the expression of MK mRNA and protein during tooth development in mouse embryos and studied the regulation of MK expression and the biological effects of MK protein in organ cultures. MK expression was restricted and preferential in the tooth area as compared to the rest of the developing maxillary and mandibular processes suggesting specific functions for MK during tooth morphogenesis. MK mRNA and protein were expressed during all stages of tooth formation (initiation, morphogenesis, and cell differentiation), and shifts of expression were observed between the epithelial and mesenchymal tissue components. However, the expression of mRNA and protein showed marked differences at some stages suggesting paracrine functions for MK. Tissue recombination experiments showed that MK gene and protein expression are regulated by epithelial-mesenchymal interactions, and, moreover, that dental tissue induces the ectopic expression of MK protein in non-dental tissue. The expression of MK gene and protein in the mandibular arch mesenchyme from the tooth region were stimulated by local application of retinoic acid in beads. Cell proliferation was inhibited in dental mesenchyme around the beads releasing MK, but this effect was modulated by simultaneous application of FGF-2. Morphogenesis and cell differentiation were inhibited in tooth germs cultured in the presence of neutralizing antibodies for MK, whereas the development of other organs (e.g., salivary gland, kidney) was unaffected. These results suggest important roles for MK in the molecular cascade that regulates tooth development.

Animals↗

PubMed2001

Administration of osteocalcin accelerates orthodontic tooth movement induced by a closed coil spring in rats.

The effect of local administration of osteocalcin (OC) on experimental tooth movement was examined in the rat. The maxillary first molar was first moved mesially with an initial tipping force of 30 g with a closed-coil spring anchored to the incisor for 10 days (n = 48). Three experimental groups (n = 8) were injected with purified rat OC at doses of 0.1, 1, and 10 micrograms, respectively. The injection into the palatal bifurcation site of the first molar was repeated daily. The control groups (n = 8) were injected with rat serum albumin (10 micrograms), phosphate buffered saline (PBS), or were not injected. Tooth movement was evaluated daily by measuring the inter-cuspal distance between the first and the second molars on a precise plaster model. The cumulative tooth movement (mm) in the 1-microgram OC-injected groups was significantly more than that in all of the control groups on day 9. The rate of tooth movement (mm/day) showed periodical elevation, with high values on days 1, 4, 7, and 9. Acceleration of tooth movement by OC was significant in the early experimental period. Subsequently, acceleration of early tooth movement by OC was histologically evaluated (n = 40). Each of four animals from the control (PBS, n = 20) and the experimental (1 microgram OC, n = 20) groups was killed daily up to 5 days. A significantly larger number of osteoclasts accumulated on the mesial alveolar bone surface in the 1-microgram OC-injected group on day 3 than that observed in control group. These results suggest that administration of OC accelerates orthodontic tooth movement due to enhancement of osteoclastogenesis on the pressure side, primarily in the early experimental period.

Acid Phosphatase↗

PubMed1979

Structure and histogenesis of tooth plates in Sagenodus inaequalis Owen considered in relation to the phylogeny of post-Devonian dipnoans.

The histology of tooth plates of Sagenodus inaequalis has been investigated to obtain information on the histogenesis of the tissue. The histological mechanisms of growth and replacement of the tooth plate are described in terms of an increase in area of the tooth plate by addition of denticles to the lateral margins of the ridges, replacement of worn dentine at the tritoral surface by basal growth of dentine and invasive growth of dentine into the surrounding bone at the anterior and medial margins. The histogenesis of a specialized character for dipnoans is described, namely hypermineralized dentine, or petrodentine, within the tooth plates. This has placed an advanced character further back in the phylogenetic organization of dipnoans than was previously recognized. The implications of these observations are discussed in relation to proposed phylogenies and previous observations on tooth plates of other dipnoans. It is concluded that Sagenodus inaequalis shared a common ancestor with both the ceratondontids and the lepidosirenids. A sequence is proposed for the phyletic relationship of tooth plate-bearing dipnoans. From a consideration of the features of histogenesis of this specialized dentine, the alternative terminologies are reviewed and petrodentine (Lison 1941) chosen for the hypermineralized dentine and syndentine (Thomasset 1928) as the collective term for the entire mass of dentine in the tooth plate.

Animals↗

PubMed1984

Tooth mortality in plantation workers and residents in Sri Lanka.

The tooth mortality of 787 Sri Lanka tea plantation workers and residents aged between 15 and 85 yr was studied in terms of missing teeth as well as teeth requiring extraction for various reasons. The mean number of missing teeth per person was 6.7 +/- 9.0. A pattern relating actual tooth loss and tooth loss adjusted to take account of teeth needing extraction was observed. Such adjustment increased the mean number of missing teeth per person by about two teeth in most age groups. The age specific pattern of tooth loss was calculated. There was an abrupt increase in tooth mortality at the ages 45-54. The age specific tooth mortality for the Sri Lankan group was consistently less than for people in several Western countries. These trends were also apparent in the mortality pattern of individual tooth types. Although there was a tendency for more women to be edentulous, a significantly higher proportion of women than men had a full complement of teeth.

Adolescent↗

PubMed1997

Predictors of tooth loss over 10 years in adult and elderly Chinese.

This study describes the incidence of tooth loss over a 10-year period in a population of rural Chinese, initially aged between 20 and 80 years. Among the 587 persons who participated in a baseline examination in 1984, 440 persons were available for a follow-up study in 1994. A total of 31 persons, mainly aged 50+ years at baseline, had become completely edentulous. Between 45% and 96% of the persons lost at least one tooth, and the average number of teeth lost ranged between 1.0 and 7.2. The distribution of the number of teeth lost was skew, indicating that a minor group of subjects had a substantially higher risk of tooth loss than the majority. Logistic regression analysis identified six significant predictors of tooth loss among those who remained dentate: age, a high number of teeth with dentinal caries lesions, a high number of teeth with caries lesions of any type, presence of teeth with attachment loss > or = 7 mm, presence of mobile teeth, and a low percentage of sites with subgingival calculus deposits. At the subject level, caries variables and periodontal disease variables seemed equally important predictors of the incidence of tooth loss over 10 years, but at the tooth level caries was a predominant cause of tooth loss in all age groups.

Adult↗

PubMed2006

Effects of smoking and drinking habits on the incidence of periodontal disease and tooth loss among Japanese males: a 4-yr longitudinal study.

OBJECTIVE: We investigated the risk of periodontal disease and tooth loss, associated with habits of smoking and alcohol consumption, in a longitudinal study. SUBJECTS AND METHODS: The subjects were 1332 Japanese males, 30-59 yr of age, who were free from periodontal disease at the baseline check-up, and who underwent a second check-up 4 yr later. Periodontal disease was diagnosed using the community periodontal index score, based on the clinical probing of pocket depth (> or = 4 mm). Smoking and alcohol consumption patterns were evaluated using a self-administered questionnaire. RESULTS: A dose-response relationship was observed between the amount of smoking and the incidence of periodontal disease in each age group. The overall odds ratios (95% confidence intervals), adjusted for age and alcohol, were 1.51 (0.95-2.22), 1.58 (1.13-2.22) and 2.81 (1.96-4.03), among smokers consuming 1-19, 20 or 21 or more cigarettes per day, respectively, with a significant linear trend (p < 0.0001). A similar association was found between smoking and tooth loss, except for the 50-59-yr-old age group. The adjusted odds ratios were 1.26 (0.60-2.64), 2.01 (1.21-2.32) and 2.06 (1.23-3.48), respectively. A significant linear trend between smoking and tooth loss was also observed (p = 0.01). Ex-smokers showed no significant difference compared with nonsmokers. We also found a significant linear trend between alcohol consumption and tooth loss among 30-39-yr-old subjects, while no relationship was observed between alcohol consumption and periodontal disease. CONCLUSION: Cigarette smoking was found to be an independent risk factor for periodontal disease and tooth loss. Alcohol consumption was a limited risk factor for tooth loss in the younger age group, but was unrelated to periodontal disease. To prevent periodontal disease and tooth loss, health practitioners need to encourage people to stop smoking or not to start.

Adult↗

PubMed2007

Evaluation of the knowledge of tooth avulsion of school professionals from Adamantina, São Paulo, Brazil.

Tooth avulsion is common in children, and emergency management in these cases is critical. This management can be made, not only by a dentist but by people who are present where the accident occurs. Consequently, knowledge of tooth avulsion is fundamental for school professionals working with children. The purpose of the present study was to evaluate the knowledge of tooth avulsion of school professionals from Adamantina, São Paulo, Brazil. For that purpose a questionnaire, including questions regarding emergency procedures for tooth avulsion, was answered by 117 teachers. The results demonstrated that 75.2% of school professionals knew the importance of emergency management and 60.6% would look for a dentist for treatment of the cases; 18.8% would reimplant the tooth and 7.6% would keep it in milk. This study showed the lack of knowledge of teachers on tooth avulsion; educational campaigns are necessary to improve the emergency management of tooth avulsion.

Adult↗

PubMed2002

Comparison of two methods of estimating 48-month tooth loss incidence.

OBJECTIVES: This paper quantifies validity of self-reported tooth loss, compares incidence using two methods (semiannual self-report, biannual clinical examination), and compares conclusions about risk factors for tooth loss using these two methods. METHODS: The Florida Dental Care Study included persons who at baseline had at least one tooth. In-person interviews and clinical examinations were conducted at baseline, 24 months, and 48 months, with semiannual telephone interviews in between. RESULTS: Agreement between self-reported and clinically derived tooth loss was high, although some statistically significant differences by certain baseline characteristics were evident. On a nominal scale (some tooth loss, none), kappa was 0.88 and percent concordance was 94 percent. On a ratio scale, Spearman's correlation was 0.90. Using self-report, the incidence estimate would have been 34 percent, as compared to 36 percent based on clinical examination. In a single bivariate (loss by self-report, loss by clinical examination) multiple logistic regression, conclusions about statistical significance and magnitude of seven risk factors for tooth loss did not differ. CONCLUSIONS: Validity of self-reported incidence was excellent. The self-reported method allowed for semiannual estimates and was less resource intensive. Substantive conclusions about tooth loss using either method were similar, although validity did differ between persons with certain baseline characteristics.

Analysis of Variance↗

PubMed2004

Life-style correlates of tooth loss in an adult Midwestern population.

OBJECTIVES: To describe life-style correlates of tooth loss in a representative rural American population. METHODS: Information on tooth loss as well as past medical history and life-style factors was obtained in a well-defined cohort of 2,764 persons 53-96 years of age in Beaver Dam, WI (1998-2000). RESULTS: There were 1,992 (68.2%) persons missing some and 447 (15.3%) missing all of their teeth. In univariable analyses, age, cigarette smoking, heavy drinking, education, multivitamin use, and diabetes status were associated with tooth loss. Tooth loss was associated with poorer self-rated health and with difficulty eating solid food and inability to enjoy some food. In multivariable models age, education, smoking, heavy drinking, and diabetes were significantly associated with tooth loss. CONCLUSIONS: Tooth loss is common in older persons and is associated with many risk factors including education, smoking, and heavy drinking. It is possible that modifying these may influence risk of tooth loss.

Adult↗

PubMed2004

Immunolocalization of Alk8 during replacement tooth development in zebrafish.

The novel type I transforming growth factor-beta (TGF-beta) family member receptor Alk8 was previously identified in a degenerate RT-PCR screen for zebrafish type I and II TGF-beta family member receptors. Functional analyses revealed that Alk8 acts through Bmp signaling pathways in early embryonic dorsoventral patterning, in neural crest cell specification, and in patterning and differentiation of neural crest cell-derived pharyngeal arch cartilages. In addition, Alk8 forms active signaling complexes with TGF-beta1 and the TGF-beta RII receptor, suggesting that Alk8 mediates cross talk between Bmp and TGF-beta subfamily members. In this study, immunohistochemical analysis was performed on zebrafish aged 2 days postfertilization to 1 year, revealing immunolocalization of Alk8 to tissues of the tooth-bearing ceratobranchial 5 (cb5) arch including dental epithelial and mesenchymal tooth tissues of developing primary and replacement teeth, mucous-producing crypt epithelium, keratinized bite plate, and developing taste buds. These results suggest roles for Alk8 in patterning tooth-bearing pharyngeal epithelium, in the initiation of tooth development, in odontoblast and ameloblast differentiation, and in osteoblast maturation. The ability for zebrafish to continuously form teeth throughout their lives allows for the comparison of Alk8 expression in both primary and replacement tooth development, revealing identical Alk8 expression profiles. This study advances our current understanding of the functions of Alk8, particularly with respect to primary and replacement tooth formation, reveals additional roles for Alk8 in dental epithelial patterning and in odontoblast, ameloblast and osteoblast differentiation, and demonstrates the utility of the zebrafish as a model for primary and replacement tooth development.

Activin Receptors, Type I↗

PubMed2001

Influences of ovariectomy on experimental tooth movement in the rat.

Estrogen withdrawal, which is important in the pathogenesis of post-menopausal osteoporosis, accelerates bone metabolism with a negative calcium balance. Therefore, it is hypothesized that estrogen deficiency could affect the rate of experimental tooth movement and alveolar bone remodeling. Six-week-old rats received a bilateral ovariectomy (OVX) or sham operation. Fourteen days later, rats were subjected to lateral tooth movement in the upper molar with nickel-titanium wire of 10 g of force. OVX significantly increased the rate of experimental tooth movement from 12 days after experimental tooth movement (p < 0.001). Eighteen days after the start of tooth movement, bone histomorphometry demonstrated that OVX significantly elevated the osteoblast surface, osteoclast surface, and number of osteoclasts (p < 0.05) in the alveolar bone. These findings indicated that estrogen deficiency caused significantly rapid orthodontic tooth movement, and that the acceleration of tooth movement could be due to the further activation of alveolar bone turnover.

Alveolar Bone Loss↗

PubMed1993

Acute toxicological effects of ingested tooth whiteners in female rats.

Tooth whiteners are considered as cosmetic agents to be used for bleaching teeth. Since tooth whitener may be swallowed during the whitening procedure, studies were conducted to determine whether ingestion of tooth whitener containing carbamide peroxide resulted in toxic effects. Adult female rats were used, and vaginal smears were examined daily to determine whether the animals were ovulating. Following an overnight fast, a single bolus of a commercial tooth whitener (5 g of tooth whitener/kg fasting body weight) was administered by gavage. Control rats received de-ionized water. After 2 h, mean respirations per min of animals receiving the tooth whitener Quik Start (contains 35% carbamide peroxide) decreased from 169 to 55, and body temperature decreased from 38.4 to 34 degrees C. Other distress signs included: labored breathing, loss of righting reflex, partial eye closure, bloody urine, and incontinence. Three of 22 animals (3/22) died within 48 h, of gastric hemorrhaging. Eight/10 rats stopped ovulating. At necropsy 2 weeks post-dosing, 10/19 animals had grossly bloated stomachs, and mucosal necrosis was observed histologically in 3. Animals receiving White & Brite or Nu-Smile (containing 10 or 15% carbamide peroxide, respectively) exhibited similar but milder symptoms. The data indicate that ingestion of large doses of commercial preparations of tooth whiteners may be acutely toxic, sometimes fatal, to female laboratory rats.

Animals↗

PubMed1997

Evaluating the validity of probing attachment loss as a surrogate for tooth mortality in a clinical trial on the elderly.

Most periodontal trials are based on the assumption that the superior treatment, as judged by short-term intangible changes in probing attachment levels (the surrogate), is also the treatment most likely to affect tooth mortality. This assumption is valid if: (1) the surrogate is informative about tooth mortality, and (2) the surrogate captures a substantial proportion of the treatment effect on tooth mortality (e.g., > 50% or 75%). The goal of this study was to evaluate whether both conditions were satisfied in a randomized controlled trial (RCT) of elders at high risk for dental diseases. The results suggested that the first condition for a valid surrogate was satisfied: Both one- and two-year changes in probing attachment level were informative about tooth mortality risk. A 1-mm loss measured over a one-year period was associated with a 56% increased tooth mortality risk (relative risk = 1.56; 95% confidence interval, 1.08 to 2.26; p = 0.017); a 1-mm loss measured over a two-year period was associated with a 102% increased risk for tooth mortality (relative risk = 2.02; 95% confidence interval, 1.26 to 3.25; p = 0.004). The second condition necessary for a valid surrogate could not be confirmed in the present trial. With 95% confidence, it was concluded that one-year changes in probing attachment level measurements did not capture a significant proportion of the treatment effect (point estimate, 6%; 95% confidence interval;-38% to 53%). No useful statements could be made regarding the proportion of treatment effect captured by two-year changes, due to the width of the confidence interval (point estimate, 18%; 95% confidence interval;-151% to 140%). It is concluded that (1) the evidence surrounding the one-year change in probing attachment level indicates that it can be ruled out as being anything more than a weak surrogate marker for tooth mortality, and (2) further research is required to study the validity of two-year change in probing attachment level as a surrogate marker. Due to characteristics of the population and the treatments investigated, the generalizability of these findings to other RCTs is questionable.

Aged↗

PubMed1998

Forty-five-year tooth survival probabilities among men in Oslo, Norway.

Changes in tooth survival probabilities over a person's lifetime have remained largely unexplored. The goal of this study was to evaluate changes in the 45-year tooth survival probabilities in a cohort of 565 Norwegian males who were examined in 1969 as young adults, and followed up into mid-life (examination years and sample sizes (n): 1971 (n = 381), 1973 (n = 292), 1975 (n = 245), 1981 (n = 228), 1988 (n = 202), and 1995 (n = 223). The results indicated that the tooth survival probabilities varied considerably both (i) among teeth within individuals, and (ii) over time. The 45-year survival probabilities for the 28 teeth fell into the following ranges: larger than 95% for incisors and cuspids; between 84% and 92% for premolars; and between 59% and 96% for molars. Over the first 4 post-eruptive decades, the tooth mortality risks (excluding orthodontic extractions) were: 1st decade, 2.0% (from 1.7 to 2.4%); 2nd decade, 0.2% (from 0.1 to 0.4%); 3rd decade, 0.6% (from 0.4 to 0.8%); and 4th decade, 1.1% (from 0.8 to 1.5%). The tooth mortality risks in the 2nd, 3rd, and 4th decades were probably somewhat underestimated (due to dropout bias), suggesting that the true underlying tooth mortality hazard function may have been V-shaped. The conclusions were that the tooth mortality hazard during the first 4 post-eruptive decades was bathtub-shaped and that it varied considerably among teeth within individuals.

Adolescent↗