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At least 415 records · Page 23Linked to original sources

PubMed2001

Apoptosis in regressive deciduous tooth germs of Suncus murinus evaluated by the the TUNEL method and electron microscopy.

Apoptosis in regressive primary (deciduous) dental primordia was examined in the embryos of Suncus murinus, which is a monophyodont. The primary tooth germs of S. murinus are temporarily formed and disappear during the embryonic period before they are calcified. Most primary tooth germs reach the bell stage and degenerate by embryonic day 22 (E22). Light microscopy on haematoxylin-eosin-stained sections revealed that intensely labelled granular substances are frequently present in the epithelial portion (enamel organs) of the deciduous tooth germs during the period from E18 to E20. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labelling method, computer-assisted three-dimensional reconstructions, and electron microscopy confirmed that these variable-sized granular substances are similar to apoptotic cells or bodies. Apoptotic structures were mainly found in the primary tooth germ located on the buccal surface of the secondary (successional) tooth germ. These results lead to the conclusion that apoptosis is closely associated with the involution and disappearance of the deciduous tooth germ in S. murinus. A primary tooth germ was observed on the buccal side of all the corresponding successional tooth germs, although the buccal surface of the secondary tooth germ of third upper molar teeth developed only to epithelial thickening without mesenchymal condensation. The findings, therefore, suggest that apoptosis is responsible for disappearance of the primary dental primordia during tooth development in S. murinus.

Animals↗

PubMed2002

Tooth loss in the very old: 13-15-year incidence among elderly Iowans.

OBJECTIVES: Very few studies have reported tooth loss incidence over a period of 10 years or more, and fewer have reported tooth loss occurrence in subjects aged 80 and older, so that the long-term pattern of tooth loss in the very old is largely unknown. This study assessed 13-15-year tooth loss incidence among a cohort of Iowans, aged 65 and older at baseline. METHODS: Oral examinations were conducted on 520 subjects beginning in 1983, and periodically until 1988, with another round of examinations conducted on surviving members of the initial cohort during 1996-98. RESULTS: Of the 73 remaining subjects, 45 subjects lost a total of 153 teeth during the period (mean=2.1 teeth lost), with a maximum of 17 teeth lost. Molars were the most commonly lost teeth, while canines and maxillary incisors were the least commonly lost. Bivariate analyses found that tooth loss was associated with untreated decay at baseline and level of periodontal attachment loss at earlier examinations. Logistic regression identified only greater severity of attachment loss as a significant risk factor for tooth loss (Adjusted odds ratio=2.4, P=0.006). The impact of tooth loss on subjects' lives was assessed using OHIP and other questions. The occurrence of tooth loss over the study period had little impact, but the number of remaining teeth significantly impacted subjects' ability to eat or chew food, swallow, or their willingness to smile. CONCLUSIONS: These results suggest that tooth loss continues in the very old, that periodontal attachment loss is associated with tooth loss in this age group, and that loss of teeth over one's lifetime does affect certain quality-of-life measures.

Aged↗

PubMed2002

Maximum clenching force of patients with moderate loss of posterior tooth support: a pilot study.

STATEMENT OF PROBLEM: Patients who have lost moderate posterior tooth support may also lose clenching force as a result of sensitivity to increased loading to the remaining teeth and possibly a loss of muscle strength, because clenching forces are limited to avoid stress to the remaining teeth. Few studies have correlated moderate posterior tooth loss with maximum clenching force. PURPOSE: The purpose of this pilot study was to test the hypothesis that moderate loss of posterior tooth support will have a significant effect on maximum clenching force. MATERIAL AND METHODS: The maximum clenching force of 44 adults, ages 28 to 76 (mean 46), with posterior tooth loss was compared with the maximum clenching force of a control group of 20 healthy full dentition adults, ages 18 to 55 (mean 30), by use of a bilateral strain-gauged transducer. The transducer consisted of 2 stainless steel plates separated by a steel sphere that balanced occlusal forces between right and left sides. Acrylic resin pads were fabricated for each patient to protect the cusps of the teeth. The overall accuracy was found to be within 2.3% of full scale over a range of 0 to 4000 N (0 to 900 lbs). The calibration reliability of the system was checked frequently by use of a dead weight of 222 N (50 lbs). Clenching forces were supported by first and second molars and second premolars when possible. The instrumentation, methods, and operator were the same for both groups. A 2-tailed Student t test (alpha=0.01) and a pooled estimate of the mean were used to determine possible statistical significance. To test for possible correlations between clenching force and lost tooth support and between clenching force and age, a linear regression correlation coefficient R was calculated. RESULTS: For the 44 subjects with posterior tooth loss, the mean clenching force was 462 N (104 lbs), with a range of 98 to 1031 N (22 to 232 lbs). This compares with a mean of 720 N (162 lbs) with a range of 244 to 1243 N (55 to 280 lbs) for the full-dentition subjects. A 2-tailed t test showed that the average difference of 258 N (58 lbs) between the 2 groups was significant (P< or =.01). There was only a moderate negative association between clenching strength and loss of mandibular tooth support (R = -0.35). Clenching force was not well correlated with age as indicated by low R values (R = 0.21, missing tooth group and R = -0.03, full dentition group). CONCLUSION: Within the limitations of this study the maximum clenching force was less (P< or =.01), by 258 N (58 lbs) on average, in subjects with moderate loss of posterior tooth support. Loss of maximum clenching force was associated with a modest negative correlation to the number of missing teeth in the mandibular arch (R = -0.35). The range of clenching force was surprisingly large for both the missing tooth (98 to 1031 N) and full dentition (244 to 1243 N) groups.

Adolescent↗

PubMed1998

Activin is an essential early mesenchymal signal in tooth development that is required for patterning of the murine dentition.

Development of the mammalian tooth has been intensively studied as a model system for epithelial/mesenchymal interactions during organogenesis, and progress has been made in identifying key molecules involved in this signaling. We show that activin betaA is expressed in presumptive tooth-germ mesenchyme and is thus a candidate for a signaling molecule in tooth development. Analysis of tooth development in activin betaA mutant embryos shows that incisor and mandibular molar teeth fail to develop beyond the bud stage. Activin betaA is thus an essential component of tooth development. Development of maxillary molars, however, is unaffected in the mutants. Using tissue recombination experiments we show that activin is required in the mesenchyme prior to bud formation and that although activin signaling from mesenchyme to epithelium takes place, mutant epithelium retains its ability to support tooth development. Implantation of beads soaked in activin A, into developing mandibles, is able to completely rescue tooth development from E11.5, but not E12.5 or E13.5, confirming that activin is an early, essential mesenchyme signal required before tooth bud formation. Normal development of maxillary molars in the absence of activin shows a position specific role for this pathway in development of dentition. Functional redundancy with activin B or other TGFbeta family members that bind to activin receptors cannot explain development of maxillary molars in the mutants since the activin-signaling pathway appears not to be active in these tooth germs. The early requirement for activin signaling in the mesenchyme in incisor and mandibular molar tooth germs must be carried-out in maxillary molar mesenchyme by other independent signaling pathways.

Activins↗

PubMed2006

Outcome of implant therapy in patients with previous tooth loss due to periodontitis.

BACKGROUND: It is frequently debated whether implant treatment in individuals with previous tooth loss due to periodontitis is characterized by an increased incidence of implant loss and peri-implantitis. OBJECTIVE: The objective of the present systematic review was to assess whether individuals with previous tooth loss due to periodontitis have an increased risk of loss of suprastructures, loss of implants, peri-implantitis, and peri-implant marginal bone loss as compared with individuals with previous tooth loss due to reasons other than periodontitis. SEARCH STRATEGY: Studies considered for inclusion were searched in MEDLINE (PubMed) and relevant journals were hand searched. Moreover, reference lists of articles selected for full-text screening as well as previously published reviews relevant for the present systematic review were searched. The search was performed by one reviewer and was restricted to human studies published from January 1, 1980 to January 1, 2006. No language restrictions were applied. SELECTION CRITERIA: Prospective and retrospective cohort studies with at least a 5-year follow-up comparing the outcome of implant treatment in individuals with periodontitis-associated and non-periodontitis-associated tooth loss, respectively, were included. The outcome measures were survival of suprastructures, survival of implants, occurrence of peri-implantitis, and peri-implant marginal bone loss. The 5- and 10-year time points were evaluated. DATA COLLECTION AND ANALYSIS: Screening of eligible studies, methodological quality assessment, and data extraction were conducted in duplicate and independently by two of the authors. The authors were contacted for missing information. Results were expressed as random effect models using weighted mean differences for continuous outcomes and relative risk for dichotomous outcomes with 95% confidence intervals (CIs). MAIN RESULTS: Two studies with a 5- and 10-year follow-up, respectively, were identified including a total of 33 patients with tooth loss due to periodontitis and 70 patients with non-periodontitis-associated tooth loss. There was no significant difference in the survival of the suprastructures after 5 years. Furthermore, there were no significant differences in the survival of the implants after 5 and 10 years. However, there were significantly more patients affected by peri-implantitis in the group with periodontitis-associated tooth loss during the 10-year follow-up period, risk ratio (RR) 9 (95% CI 3.94-20.57). Moreover, significantly increased peri-implant marginal bone loss was observed in patients with periodontitis-associated tooth loss after 5 years, mean difference 0.5 mm (95% CI 0.06-0.94). CONCLUSIONS: The survival of the suprastructures and the implants was not significantly different in individuals with periodontitis-associated and non-periodontitis-associated tooth loss. However, significantly increased incidence of peri-implantitis and significantly increased peri-implant marginal bone loss were revealed in individuals with periodontitis-associated tooth loss. The small sample size and the methodological quality assessment of the two studies suggest that the results should be interpreted with caution. Consequently, further long-term studies focusing particularly on the outcome of implant treatment in young adults with aggressive periodontitis are needed before final conclusions can be drawn about the outcome of implant treatment in patients with a history of periodontitis.

Alveolar Bone Loss↗

PubMed1996

Tooth thickness at the furcation entrance of lower molars.

Better understanding of the furcation anatomy may serve to decrease the risk of pulpal injury during rotary odontoplasty, a procedure often used in conjunction with guided tissue regeneration. The purpose of this study was to determine (i) the tooth thickness about the furcation entrance of lower molars, and (ii) whether there is a relationship between tooth thickness and patient age. 40 mandibular 1st molars (M1) (mean age = 36.2; range 10-65 years) and 40 mandibular 2nd molars (M2) (mean age = 37.9; range 14-70 years) were collected. Age, gender and furcation involvement (if any) were noted for each tooth at the time of extraction. Teeth were sectioned in half, buccal-lingual, at the furcation entrance with a rotary diamond blade. A standardized linear reference scale was placed on each experimental section and an 8 x 10 in. photograph generated. The distance from the floor of the pulp chamber to 5 predetermined sites on the root surface was calculated. The data were expressed as (a) the mean of each site and (b) the mean of each tooth (the average of the 5 points of each tooth). Analysis of covariance failed to show a relationship between thickness measurements and gender or furcation involvement. Thus, the data was subjected to simple regression analysis to determine the relationship of age with tooth and cementum thickness. This study revealed that by site, the mean measurements ranged from 2.7-3.0 mm for both M1 and M2. The single least/greatest measurements of the 5 sites were for M1: 1.6/4.7 mm and for M2: 1.8/4.2 mm. By tooth, the average distance from the pulp to the root surface was 2.83 mm (+/- 0.49) for M1 and 2.88 mm (+/- 0.44) for M2. Regression analysis of tooth thickness with age was significant for M1 only. The maximum slope of the 5 sites was approximately 0.3 mm/10 years. No relationship was found between cementum thickness and age for either tooth group. The results of this study indicate that the majority of times the pulp is 1.6-4.2 mm from the root surface in the vicinity of the furcation entrance of lower 1st and 2nd molars. Although tooth thickness in this area may increase with age, the amount is not enough to forego judicious odontoplasty on older patients.

Adolescent↗

PubMed2004

Predictors of tooth loss in two US adult populations.

OBJECTIVES: This study determines tooth loss rate over a 10-year period and identifies predictors of tooth loss in two separate US adult longitudinal study populations. METHODS: Subjects from the Baltimore Longitudinal Study of Aging (BLSA), consisting of 47 men and 47 women, ages ranging from 30 to 69 years, were compared to subjects from the VA Dental Longitudinal Study (VADLS) in Boston, MA, consisting of 481 men in the same age range. Baseline and follow-up examinations were performed on each cohort over a 10-year period. Using multivariate regression models, significant predictors of tooth loss were identified. RESULTS: A mean rate of tooth loss of 1.5 teeth lost per 10 years was noted in the VADLS cohort compared to 0.6 teeth lost per 10 years in the BLSA (P < .001). Combining subjects from both populations, significant predictors of tooth loss were baseline values of: percent of teeth with restorations, mean probing pocket depth score, age, tobacco use, alcohol consumption, number of teeth present, and male sex. However, the set of significant predictor variables differed between the two populations and sexes. In BLSA men, number of teeth present, percent of teeth with restorations, mean probing pocket depth score, and alcohol consumption, but not age, were significant, while in BLSA women, only age was a significant predictor. CONCLUSIONS: Over a 10-year period, the incidence of tooth loss, the rates of tooth loss, and the predictors of tooth loss were found to vary by population and by sex. These results illustrate the limits of generalizing tooth loss findings across different study cohorts and indicate that there may exist important differences in risk factors for tooth loss among US adult populations.

Adult↗

PubMed1997

The genetic control of early tooth development.

Most vertebrate organs begin their initial formation by a common, developmentally conserved pattern of inductive tissue interactions between two tissues. The developing tooth germ is a prototype for such inductive tissue interactions and provides a powerful experimental system for elucidation of the genetic pathways involved in organogenesis. Members of the Msx homeobox gene family are expressed at sites of epithelial-mesenchymal interaction during embryogenesis, including the tooth. The important role that Msx genes play in tooth development is exemplified by mice lacking Msx gene function. Msxl-deficient mice exhibit an arrest in tooth development at the bud stage, while Msx2-deficient mice exhibit late defects in tooth development. The co-expression of Msx, Bmp, Lefl, and Activin beta A genes and the coincidence of tooth phenotypes in the various knockout mice suggest that these genes reside within a common genetic pathway. Results summarized here indicate that Msxl is required for the transmission of Bmp4 expression from dental epithelium to mesenchyme and also for Lefl expression. In addition, we consider the role of other signaling molecules in the epithelial-mesenchymal interactions leading to tooth formation, the role that transcription factors such as Msx play in the propagation of inductive signals, and the role of extracellular matrix. Last, as a unifying mechanism to explain the disparate tooth phenotypes in Msxl- and Msx2-deficient mice, we propose that later steps in tooth morphogenesis molecularly resemble those in early tooth development.

Ameloblasts↗

PubMed1995

Development and physiological degradation of tooth buds and development of rudiment of baleen plate in southern minke whale, Balaenoptera acutorostrata.

The development and degradation of temporary tooth buds and the development of rudiment of baleen plate were observed by gross-anatomical and histological examinations in twenty-four fetuses of the southern minke whale, Balaenoptera acutorostrata. The primary patterns of development of tooth buds were similar to those of deciduous tooth buds in the terrestrial species. Degradation of tooth buds was observed in the fetuses more than 615 mm body length (BL) and might proceed throughout the dental surface of the tooth buds. That degradation pattern was a little different from that of deciduous tooth buds in terrestrial species, which has a limited degradation area at the root of the tooth buds. In the fetuses with 135 and 153 mm BL, the upper jaw had a larger number of tooth buds than the lower jaw, although the number of buds varied in different individuals. Formation of rudiment of baleen plate was observed with degraded tooth buds in the fetus of 903 mm BL and it may be induced by the degradation of tooth buds.

Animals↗

PubMed2006

Different roles of Runx2 during early neural crest-derived bone and tooth development.

UNLABELLED: We compared gene expression profiles between Runx2 null mutant mice and their wildtype littermates. Most Runx2-dependent genes in bones were different from those in teeth, implying that the target genes of Runx2 are tissue-dependent. In vitro experiments determined that Runx2 is a part of the FGF and BMP signaling pathways in tooth and bone development, respectively. INTRODUCTION: Runx2 (Cbfa1) is expressed in the neural crest-derived mesenchyme of developing bone and tooth. Runx2 homozygous null mice lack bone through a failure in osteoblast differentiation and have arrested tooth development at the late bud stage. The aim of this study was to discover and compare the identities and the roles of Runx2 target genes in bone and tooth development. MATERIALS AND METHODS: Wildtype and Runx2-/- tissue was collected from mouse embryos, and gene expression was compared by Affymetrix microarray analysis and radioactive in situ hybridization of embryonic tissue sections (E12-E14). Induction of target genes by growth factors in bone and tooth tissue was studied using in vitro experiments, including a novel method involving hanging-drop cultures and RT-PCR. RESULTS: Thirteen bone and four tooth genes were identified that are Runx2-dependent. The identities of these genes do not significantly overlap between bone and tooth, indicating tissue specificity of several genes regulated by Runx2. Genes downregulated in bone development in Runx2 null mutants were Bambi, Bmp4, Bono1, Dkk1, Fgf receptor1, Gli1, Lef1, Patched, Prostaglandin F receptor1, Tcf1, Tgfbeta1, Wnt10a, and Wnt10b. Several of these genes were induced by BMPs in bone tissue in a Runx2-independent manner. Genes downregulated in tooth development were Dkk1, Dusp6, Enpp1, and Igfbp3. These genes were all induced by fibroblast growth factors (FGFs) in dental tissue. FGF-induction of Dkk1 was completely dependent on Runx2 function. CONCLUSIONS: The contrasting identities and distinctive mechanisms that stimulate the expression of Runx2-dependent genes in bone and tooth development imply that the developmental roles of Runx2 in these separate tissues are different. In tooth development, Dkk1 may be a direct transcriptional target of Runx2. Bone genes were stimulated by BMP4 before the formation of the ossification center, suggesting that BMPs may mediate the early epithelial-mesenchymal interactions involved in bone formation.

Animals↗

PubMedDate not supplied

[Experimental model of tooth mobility in the human "in vivo"].

The aim of the present study was to investigate experimentally the mechanical properties of tooth deflection under external loading. These properties have a significant impact on tooth movement during orthodontic treatment. The stresses and strains caused by tooth movement influence bone remodelling, which is the basis of orthodontic treatment. The movement of a tooth as a direct reaction to the forces acting on it is termed "initial" movement. It is nonlinear and has a clearly time-dependent component. While the initial tooth movement represents the totality of the reaction mechanisms of all the tissues of the tooth unit, it is determined primarily by the mechanical properties of the periodontal ligament (PDL). The PDL is the softest tissue of the tooth unit and is therefore subject to the largest deformations when forces act on the crown of the tooth. The objective of orthodontic treatment is to achieve as precise and rapid tooth movement as possible, without provoking such undesired effects as bone and root resorption. To enable the implementation of an optimal orthodontic force system that meets these requirements, a thorough knowledge of the biomechanics of tooth movement is a must.

Biomechanical Phenomena↗

PubMed1999

Prognosis versus actual outcome. IV. The effectiveness of clinical parameters and IL-1 genotype in accurately predicting prognoses and tooth survival.

BACKGROUND: Recently, a genetic marker (IL-1 genotype) that identifies individuals at higher risk for developing severe periodontal disease was discovered. A subgroup of the population reported on earlier was evaluated to determine if knowledge of the patient's IL-1 genotype would improve accuracy in assignment of prognoses and prediction of tooth loss. METHODS: This subgroup consisted of 42 patients (1,044 teeth) in maintenance care for 14 years; 16 tested IL-1 genotype-positive (IL-1GP). Nine were smokers, and 30 had a history of smoking, with an average of 29.44 pack years. A multiple Cox regression model and Kaplan-Meier survival plots were fit to the subset of patients to evaluate tooth loss. RESULTS: Both IL-1GP and heavy smoking were significantly related to tooth loss. A positive IL-1 genotype increased the risk of tooth loss by 2.7 times, and heavy smoking by 2.9 times. The combined effect of IL-1GP and heavy smoking increased the risk of tooth loss by 7.7 times. The value of clinical parameters traditionally used to assign prognosis was found to be dependent on IL-genotype and smoking status. In the model that included IL-1 genotype and heavy smoking, none of the clinical parameters added significantly to the model for tooth loss while mobility, probing depth, crown-to-root ratio, and percent bone loss added significantly to the model, which included IL-1 genotype in non-smokers. IL-1GP patients and patients who smoked heavily demonstrated a much worse tooth survival rate when compared to IL-1 genotype-negative patients and non-smokers, respectively. CONCLUSIONS: Knowledge of the patient's IL-1 genotype and smoking status will improve the clinician's ability to accurately assign prognosis and predict tooth survival. Clinical implications are as follows. Investigators were unable to judge which patients would be IL-GP or negative based on their clinical presentation or family history of tooth loss due to periodontal disease. Since periodontal diseases are multifactorial, knowledge of the patient's genotype is more important in predicting future risk than explaining past disease. Knowledge of IL-1 genotype status would be important in developing a treatment plan and predicting tooth survival for a new patient who smokes and presents with periodontal disease, especially if restorative care is needed. Knowledge of a maintenance patient's IL-1 status would help target therapy for non-responding areas; one would be less likely to take a "wait and see approach" with IL-1GP patients. IL-1 positive non-smokers can be successfully treated and maintained over long periods of time.

Adult↗

PubMedDate not supplied

Bonding efficacy of single-step self-etch systems to sound primary and permanent tooth dentin.

Currently, there is little information regarding the bonding efficacy of single-step self-etch systems to primary tooth dentin. This study examined the microtensile bond strength of single-step self-etch systems (Clearfil tri-S Bond and One-Up Bond F Plus) to sound primary and permanent tooth dentin. Adhesives were applied to flat samples of primary and permanent tooth dentin, and resin composites were bonded according to the manufacturers' instructions. After 24 hours of storage in distilled water at 37 degrees C, hour glass-shaped specimens were produced. They were subjected to microtensile testing at a crosshead speed of 1.0 mm/minute. The results were analyzed using 2-way analysis of variance (ANOVA) followed by the Tukey HSD post-hoc test (alpha=0.05). Field-emission scanning electron microscopy (FE-SEM) observations of the adhesive-treated dentin surfaces and the resin/dentin interface were also conducted. The bond strengths of primary tooth dentin were significantly lower than that of permanent tooth dentin for both self-etch systems: 44.7 +/- 10.4 versus 54.3 +/- 9.0 MPa for Clearfil tri-S Bond and 40.6 +/- 9.9 versus 50.0 +/- 8.7 MPa for One-Up Bond F Plus (p<0.001). There was no statistically significant interaction between the type of adhesive system and the dentin substrate (p=0.957). Although there was no statistically significant difference in the mean values among the different adhesive systems (p=0.094), there was a statistically significant difference in mean values among the different dentin substrates (p<0.001), which were lower for primary tooth dentin than for permanent tooth dentin. The failure modes were also independent of the type of dentin but dependent on the adhesive systems, an equal distribution among the 3 types of failure for Clearfil tri-S Bond and cohesive failures in adhesives for One-Up Bond F Plus. FE-SEM observations of dentin to which adhesive had been applied revealed that the smear layer had been removed and the collagen fibers exposed. Though the bond strengths to primary tooth dentin were lower than to permanent tooth dentin, excellent adaptation of the single-step self-etch systems to both dentin substrates was observed by FE-SEM. Further studies are required to determine the long-term clinical performance of these adhesive systems when applied to primary tooth dentin.

Adhesives↗

PubMed1999

Developing permanent tooth length as an estimate of age.

Developing teeth are widely used to predict age in archaeology and forensic science. Regression equations of tooth length for age is a direct method, however, data for permanent teeth is incomplete. The aims of this study were: (a) to calculate regression equations predicting age from tooth length of all permanent teeth from birth to maturity, and (b) to evaluate the difference between radiographic and actual tooth length. The sample studied (N = 76, age range 0 to 19 years) was the Spitalfields juveniles of recorded age-at-death. Tooth length was measured from incisal tip to developing edge of crown or root of 354 dissected teeth. Data for upper and lower teeth were combined except for the lateral incisor. The least squares regression method was used to analyze the data for each tooth type; age being regressed against tooth length for prediction. For most tooth types, growth followed an S-shaped (polynomial) curve with initial fast growth and a further growth spurt around the time of mid root formation. No difference was found between radiographic and true tooth length. These regression equations provide an easy method of predicting age from any developing permanent tooth by measuring tooth length from isolated teeth or from unmagnified, undistorted radiographs.

Adolescent↗

PubMed2004

Prevalence of intrinsic tooth discolouration among 11-16 year-old Nigerians.

600 children aged 12 to 16 years were examined in the Surulere Local Government Area of Lagos State, Nigeria to determine the prevalence and types of intrinsic tooth discoloration. 306 boys and 294 girls were selected from six schools (3 primary and 3 secondary schools) by stratified random sampling. The teeth of the children were examined in a wet state for intrinsic stains, however, no attempt was made at aetiologic diagnosis of enamel hypoplasia and enamel opacities, diagnosis were based on clinical presentations. A 37.7% (226) prevalence of intrinsic tooth discolouration was recorded among the subjects. 36.0% (110) of the boys and 39.5% (116) of the girls had intrinsic tooth discolourations. The differences in prevalence of intrinsic tooth discolouration among the sexes and among the social classes were not statistically significant (p = 0.375 and p = 0.272). There was, however, a statistical difference in prevalence of intrinsic tooth discolouration among the age categories (p = 0.0013), with the older adolescents showing a higher prevalence of stains. This is linked to the greater possibility of presenting with acquired intrinsic tooth discolouration as one gets older. The commonest types of intrinsic tooth discoloration were enamel opacities (23.0%), tetracycline staining (9.2%) and enamel hypoplasia (7.3%). Other intrinsic tooth discolourations were those due to dental caries (4.3%), pulp necrosis/ haemorrhage (0.8%), toothwear (0.3%), and discoloured restorations (0.3%). A very low level of utilisation of dental services was noted, with 91.5% (549) of the subjects reporting that they had never visited a dentist. The common intrinsic tooth discolorations seen in the study are those usually associated with childhood malnutrition, preventable childhood diseases and the irrational use of drugs (tetracyclines). There is a need to intensify child immunization efforts in the community as well as health education and promotion activities geared toward proper nutrition and the rational use of drugs. The establishment of school meals in primary and secondary schools in the LGA will go a long way in improving nutrition and prevent the tooth discolouration types associated with poor nutrition. Dental services may be made more available, accessible and affordable for the children by the establishment of a school oral healthcare programme.

Adolescent↗

PubMedDate not supplied

Accuracy and precision of a system for assessing severity of tooth wear.

PURPOSE: The purpose of this study was to introduce a computer-assisted quantitative tooth wear-analyzing system and test its accuracy and precision. MATERIALS AND METHODS: An image of a horizontally projected dental arch was captured, and the facet area of each tooth was calculated using a digital image analyzer. For normalization, the facet area of the individual tooth was divided by the total area of the corresponding tooth; this result was the tooth wear score. The accuracy and precision of this method were determined through the intraclass correlation coefficient using 10 dental casts. Tooth wear on the dental casts of 50 subjects was actually measured. RESULTS: The accuracy of the tooth wear score determined by a newly trained examiner was greater than 0.85 of the intraclass correlation coefficient; this was tested against the score determined by consensus of three experienced examiners. The reproducibility within a 1-week interval was also greater than 0.85. With regard to the tooth wear score from 50 sets of dental casts, the distribution of tooth wear was generally consistent with data reported in the literature. CONCLUSION: The results suggest that the newly trained examiner can exhibit adequate accuracy and precision after appropriate training in identifying tooth wear facets. Recorded data from 50 subjects added face validity to this new system.

Adult↗

PubMed1989

[Changes in the microvascular pattern of the periodontal ligament in an experimental tooth extrusion].

Forty eight adult cats were employed to investigate the serial changes of vascular patterns of the periodontal ligament on tooth extrusion. The right upper canines have been successively extruded (initial load 40 gr) with a open coil spring. The experimental periods were set on 1, 2, 3, 4 and 6 weeks respectively. On each experimental period, the microvascular casts of the periodontal ligament and alveolar bone around the experimental tooth were prepared for the scanning electron microscopy, utilizing the acrylic plastic injection method (Taniguchi and Ohta, et al. 1952 and 1955). And the serial sections of the surrounding tissues of the experimental tooth were made. In order to elucidate the mode of the tooth movement, the load of applied force and the distance of extrusion were measured. Results obtained were as follows: 1. The experimental tooth was extruded rapidly during first two weeks. The speed reduced gradually afterwards. 2. The new vascularization was seen around the apex first, then widely spread in the periodontal ligament. And the remarkable trabecula-shaped bone formation were observed around the venous networks of the root apex after two week period. 3. The tissue reactions after the tooth extrusion delayed in comparison with the movement of the tooth. 4. Although the tissue reactions of the root apex of the extruded tooth were originally similar to the one in the transverse tooth movement, slight differences were found in timing of the tissue change and shape of the capillary network. The findings of the tissue change showed that the light force was indicated in extrusion of the tooth. And the range of action of the force applied should be limited in orthodontic clinic.

Alveolar Process↗

PubMed2002

No developmental failure of cultured tooth germs from osteopetrotic (op/op) mice.

BACKGROUND: Incisor tooth germs of osteopetrotic (op/op) mice are known to fail to erupt, but form odontomas in their root apices instead, due to invasion of alveolar bone trabeculae into the tooth germs. The purpose of this study is to determine if the tooth developmental failures in op/op mice are intrinsic or secondarily arise as a result of the defective bone metabolism due to lack of macrophage colony-stimulating factor (M-CSF). METHODS: We isolated mandibular first molar tooth germs from normal and op/op mice and cultured them under conditions with or without bone tissues which had been formed around tooth germs. RESULTS: Tooth germs from normal mice, cultured for a week, showed almost the same developmental features as those of mice with the corresponding age. They were surrounded with dental follicular tissues and were never invaded by bone trabeculae. On the other hand, op/op tooth germs cultured in the presence of bone components were invaded by alveolar bone trabeculae around tooth germs in the same manner as shown in vivo. When cultured without bone, they developed without any interruptions. CONCLUSIONS: These findings indicated that op/op tooth germs had potential for normal development and that their abnormal development was a secondary phenomenon caused by lack of bone remodeling in the early phase of odontogenesis.

Animals↗