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At least 991 records · Page 55Linked to original sources
PubMed2003

Prevalence of traumatic crown fractures to permanent incisors in a childhood population: Móstoles, Spain.

- The aim of this study was to ascertain the prevalence of traumatic crown fractures in a childhood population and identify the risk factors associated with the same. A cross-sectional study was conducted, covering 470 schoolchildren and surveying socio-demographic variables, overweight, overbite, number of teeth, cause, setting, season, type of injury and restoration. We measured prevalence, performed univariate and multivariate analyses of risk factors for crown fracture, and calculated the Odds Ratio (OR) and its 95% confidence intervals (95% CI). Prevalence of traumatic crown fractures to permanent incisors was 17.4% (95% CI: 14-20.8). Falls were the most frequent cause of dental trauma (43.9%). Boys and children with overbite registered a 2.13- and 1.81-fold higher risk of crown fractures, respectively. Owing to high prevalence, crown fractures in schoolchildren aged 10 years constitute a public health problem. Being male and having overbite are risk factors for crown fracture. Healthcare promotion and education at health centres is called for to prevent such injuries.

Analysis of Variance↗
PubMed2003

Regression equations for determining mesiodistal crown diameters of canines and premolars.

In this study, regression equations (prediction equations) were established for the purpose of accurately predicting the widths of the crowns of unerupted canines (C) and premolars (P1 and P2) on the basis of the measured mesiodistal diameter (MDD) and vestibulooral diameter (VOD) of the crowns of the erupted central and lateral incisors (I1, I2) and first permanent molars (M1). On the plaster casts of 120 subjects (60 boys and 60 girls), MDD and VOD of the crowns of I1, I2, C, both P1 and P2, and M1 on both sides in both jaws were measured twice, with a time distance between measurements. Gradual regression equations were derived on the basis of the measurement results, by which the sums of the widths of crowns of C, P1, and P2 can be predicted using three to five predictors. The coefficients of multiple correlations regarding the sex and the jaw varied from 0.79 to 0.85.

Adolescent↗
PubMed1997

Pulp survival and hard tissue formation subsequent to dental trauma. A clinical and histological study of uncomplicated crown fractures and luxation injuries.

Traumatic injuries in children and adolescents are a common problem, and the prevalence of such injuries has increased over the last 10-20 years. The purpose of the present investigation was to evaluate long-term results following uncomplicated crown fractures and luxations involving subsequent pulp canal obliteration. A total of 198 patients with 488 injured permanent teeth were available for clinical examination (15 year follow-up), of which 102 also answered a questionnaire and were interviewed before oral examination. Further, 82 permanent incisors presenting with pulp canal obliteration (PCO) were followed for a period of 7 to 22 yr. (mean 16 yr.). The histological evaluation of luxation injuries was performed on 123 primary teeth from 98 patients. In the experimental study (crown fractures), 64 monkey permanent maxillary and mandibular central incisors and canines were subjected to different treatment alternatives at the time of fracture. The findings in the follow-up study showed very little pulpal response to crown fracture and subsequent restorative procedures as long as there was no concomitant periodontal injury. Approximately every fourth resin composite restoration was rated unacceptable at the clinical examination. The interview showed that half of the individuals were dissatisfied with the color and/or anatomic form of the composite restoration. PCO was found in all luxation categories, and according to the survival curve, the 20-year pulp survival rate diagnosed with X-ray was 84%. Although the risk for pulp necrosis (PN) increased with time, routine endodontic intervention of teeth with ongoing PCO of the root canal did not seem justified. The histological study showed that changes in dentin were represented by occlusion of the dentinal tubules and deposition of tertiary dentin. The tertiary dentin were classified as either dentin-like, bone-like or fibrotic. In the experimental study, few changes were observed in the pulp 3 months after crown fractures, irrespective of treatment alternative.

Adolescent↗
PubMed1997

A scanning electron microscopy study of disturbances in the developing rat molar induced by cyclophosphamide.

Scanning electron microscopy was used to study the effect of cyclophosphamide (Cy) on molar development in 18 Sprague-Dawley rats from 15 to 48 days of age after birth. Doses of 30 mg/kg body weight of Cy dissolved in 1 ml 0.9% NaCl were given to the rats at 10 and 13 days of age. Eighteen control rats had injections of 1 ml 0.9% NaCl at the same ages. The most obvious changes in the experimental teeth were found in the developing roots of the first and second molars and in both the crown and roots of the third molar. The roots of the first and second molars were short and showed apical closure in the experimental rats. In addition to the disturbances in crown and root formation, the third molars were also significantly reduced in total size as compared with the third molars in the control rats.

Alopecia↗
PubMed2002

Correlation between mandibular central incisor proclination and gingival recession during fixed appliance therapy.

The purpose of this study was to determine whether proclination of mandibular central incisors during fixed appliance therapy results in gingival recession. Complete records of 67 patients (39 female and 28 male patients; mean age, 16.4 years; age range, 10-45 years) were used in this retrospective case-control study. Using pretreatment and posttreatment lateral cephalograms, the change in mandibular central incisor inclination was measured to divide the patients into an experimental group (proclination) and a control group (no proclination). Changes in clinical crown length were determined from pretreatment and posttreatment study models, and changes in gingival recession were determined from intraoral slides. Eight of the 67 patients exhibited a measurable increase in gingival recession of at least 0.5 mm, and 27 patients had an increase in clinical crown length of at least 0.5 mm. Statistical analyses showed no correlation between mandibular central incisor proclination and gingival recession or clinical crown length. A t-test analysis showed no statistically significant difference in gingival recession or change in clinical crown length between patients whose mandibular central incisors were proclined and those whose incisors were not proclined. Multiple regression analysis demonstrated that age, sex, race, treatment duration, extraction, treatment type, Angle classification, and proclination were not related to gingival recession or change in clinical crown length of mandibular central incisors. We conclude that the degree of proclination of mandibular central incisors during fixed appliance therapy was not correlated to gingival recession in this sample.

Adolescent↗
PubMed2006

Cessation of Fgf10 signaling, resulting in a defective dental epithelial stem cell compartment, leads to the transition from crown to root formation.

Mouse, rat and human molars begin to form root after the completion of crown formation. In these teeth, fibroblast growth factor (Fgf) 10 disappears in the transitional stage from crown formation to root. By contrast, rodent incisors and vole molars demonstrate continuous growth, owing to the formation and maintenance of a stem cell compartment by the constant expression of Fgf10. To clarify the relationship between root formation and disappearance of Fgf10, we carried out two experiments for the loss and gain of Fgf10 function. First, we examined postnatal growth in the incisors of Fgf10-deficient mice, which have the defect of a dental epithelial stem cell compartment referred to as ;apical bud', after implantation under the kidney capsule. The growth at the labial side in the mutant mice mimics the development of limited-growth teeth. 5'-Bromo-2'-deoxyuridine (BrdU) labeling and cytokeratin (CK) 14 and Notch2 immunostaining suggested that the inhibition of inner enamel epithelium growth and the more-active proliferation of the outer enamel epithelium and/or stellate reticulum result in Hertwig's epithelial root sheath formation. Second, we examined the effects of Fgf10 overexpression in the transitional stage of molar germs, which led to the formation of apical bud involving in the inhibition of HERS formation. Taken together, these results suggest that the disappearance of Fgf10 signaling leads to the transition from crown to root formation, owing to the loss of a dental epithelial stem cell compartment.

Animals↗
PubMed1997

Mesiodistal crown diameters of the primary and permanent teeth in southern Chinese--a longitudinal study.

The mesiodistal crown diameters of the primary and permanent teeth were measured on serial casts of 112 Hong Kong Southern Chinese (61 males and 51 females) taken at 5.68 and 12.31 years of age. None of the teeth showed significant sex difference in bilateral asymmetry, and significant bilateral asymmetry was found only for the upper primary second molars. The asymmetries were small and the sizes of the antimeres were averaged. Posterior teeth were generally less variable than anterior teeth in both dentitions in Chinese, which is contrary to other reports, but the anterior tooth of each morphological class was, in general, less variable than the posterior member. Male teeth were larger than those of females except for the lower central and lateral incisors in both dentitions, but the difference was not statistically significant. None of the primary teeth nor three of the permanent teeth were found to have significant sex differences in size. Percentage sexual dimorphism ranged from 0.06 to 1.97 per cent for the primary teeth and from 0.36 to 5.27 per cent for the permanent teeth. In the primary dentition, molars were the most dimorphic teeth in both arches, while upper incisors and lower canine were the least dimorphic teeth in their own arch. Among the permanent teeth, the canines were the most dimorphic and the incisors were among the least dimorphic teeth in both arches. Tooth sizes in both dentitions were, in general, larger than those of the Caucasians, comparable with Northern Chinese, but smaller than those of Australian Aboriginals.

Asian People↗
PubMed2005

Factors associated with mandibular third molar eruption and impaction.

A retrospective study, using panoramic radiographs, was conducted on 152 Taiwanese (72 males and 80 females) to investigate mandibular third molar eruption and impaction. The following measurements were made: inclinations and mesiodistal crown widths of the mandibular molars, vertical and horizontal spaces between the distal surface of the second molar and the anterior surface of the ramus, lengths and widths of the mandibular ramus and body, the ramus inclination, the mandibular plane angle, and the mandibular gonial angle. Differences between non-impaction and impaction groups were studied, and the variables were analyzed with multivariate discriminatory analysis. Significant differences between the two groups were found; variables describing spaces between the anterior of the ramus and the distal of the mandibular second molar and tooth size appeared to be the primary contributors to the differences observed.

Adult↗
PubMed2000

Human remains from Blombos Cave, South Africa: (1997-1998 excavations).

The Middle Stone Age (MSA) layers at Blombos Cave contain abundant bifacial Still Bay points, formal and ad hoc bone artefacts, and an intentionally incised bone piece. These artefacts add weight to arguments that some aspects of modern human behavior developed earlier in sub-Saharan Africa than elsewhere. Four human teeth were recovered from the MSA strata at Blombos during the 1997-1998 excavations. Two are heavily worn deciduous teeth, and two are incomplete permanent premolar crowns. The Blombos di(1)is comparatively large in relation to modern African homologues, falling within the lower part of the observed Neandertal range. The dm(1)and P(3)are comparable to modern teeth and smaller than most Neandertal crowns. The premolars preserve horizontal circum-cervical striae that suggest palliative toothpick use. The di(1)evinces labial scratches that resemble neither the "cutmarks" that have been observed on Neandertal incisors, nor the striae that have been recorded on modern human teeth.

Animals↗
PubMed2002

Consequences of crown fractures with pulpal exposure: histopathological evaluation in dogs.

When a crown fracture involving pulpal exposure is produced, the therapeutic treatment to be applied depends to a great extent on the general histopathological condition of the exposed pulp. Hence, the objective of this study was to evaluate histopathological and bacteriological changes occurring in dental tissue and periradicular tissue of crown-fractured teeth with pulpal exposure. Twenty-four anterior teeth (central and lateral incisors) from the maxillary teeth of four young, adult Mongrel dogs were used. At 48 and 72 h after performing the crown fractures, the animals were sacrificed and the results evaluated. Both observation periods revealed the existence of an area of superficial inflammation with the formation of hyperplastic tissue towards the external surface. Intense neutrophilic infiltrate was observed below it. Mean depth of inflammation was greater at 48 h (4633.33 microm) than at 72 h (3933.33 microm), perhaps coinciding with the bigger pulp chamber opening (x1332.14 microm at 48 h vs. x479.52 microm at 72 h). Upon approaching the cervical portion, the inflammation became less. Bacterial contamination was constant in all the cases evaluated, worsening the histopathological findings with exposure time. This study demonstrates that when a crown fracture with pulpal exposure is produced, the success in treating it depends partly on how quickly therapeutic treatment is administered.

Animals↗
PubMed2001

Morphological characteristics of the deciduous teeth.

The morphology of the deciduous teeth was investigated. The mean mesiodistal crown dimensions of the deciduous canine, first and second molars and the mean buccolingual crown dimensions of the deciduous second molars in both dental arches of boys were significantly larger than that of girls. The upper deciduous first molar of girls was slender buccolingually and the lower deciduous second molar of boys was slender mesiodistally.

Child, Preschool↗
PubMed1996

Glandular odontogenic cyst with hyaline bodies: an unusual dentigerous presentation.

We present an unusual case of glandular odontogenic cyst (GOC) enclosing the crown of an impacted canine that developed in the anterior mandible in a 54-year-old woman. Microscopically, it contained numerous glandular structures and hyaline bodies in the epithelial lining. The present rare case is sufficiently distinctive to be considered a dentigerous variant of GOC.

Cuspid↗
PubMed2004

Collagen cross-linking and ultimate tensile strength in dentin.

Several studies have indicated differences in bond strength of dental materials to crown and root dentin. To investigate the potential differences in matrix properties between these locations, we analyzed upper root and crown dentin in human third molars for ultimate tensile strength and collagen biochemistry. In both locations, tensile strength tested perpendicular to the direction of dentinal tubules (undemineralized crown = 140.4 +/- 48.6/root = 95.9 +/- 26.1; demineralized crown = 16.6 +/- 6.3/root = 29.0 +/- 12.4) was greater than that tested parallel to the tubular direction (undemineralized crown = 73.1 +/- 21.2/root = 63.2 +/- 22.6; demineralized crown = 9.0 +/- 3.9/root = 16.2 +/- 8.0). The demineralized specimens showed significantly greater tensile strength in root than in crown. Although the collagen content was comparable in both locations, two major collagen cross-links, dehydrodihydroxylysinonorleucine/its ketoamine and pyridinoline, were significantly higher in the root (by ~ 30 and ~ 55%, respectively) when compared with those in the crown. These results indicate that the profile of collagen cross-linking varies as a function of anatomical location in dentin and that the difference may partly explain the site-specific tensile strength.

Adolescent↗
PubMed2000

Clinical crown length changes from age 12-19 years: a longitudinal study.

OBJECTIVE: The objective of this study was to investigate the relationship between age, gender and clinical crown length using a longitudinal study design. METHOD: Four hundred and fifty-six sets of study models initially obtained for a large prospective longitudinal cohort study of orthodontic needs were examined. Each set of models corresponded to subjects at three different ages: 11-12, 14-15 and 18-19years old. The clinical crown height of the maxillary right central incisor (11), maxillary right canine (13), maxillary left lateral incisor (22) and mandibular left central incisor (31) was measured from gingival crest to the incisal edge using digital calipers. RESULTS: Analysis revealed a significant (p<0.0001) age effect on crown length for all four teeth investigated. A significant gender effect was found in relation to the maxillary right canine, maxillary right central incisor and maxillary left lateral incisor. Pairwise comparisons of the means for each age group for the maxillary right canine, maxillary right central incisor and maxillary left lateral incisor revealed significant (p<0. 0001) increases in clinical crown length between each assessment period. CONCLUSION: The findings of the present study indicate that, the process of passive eruption, resulting in increased clinical crown length appears to continue throughout the teenage years. This finding is considered to be of importance to the clinician making treatment decisions for teenagers and young adults requiring treatment in the anterior segments of the mouth.

Adolescent↗
PubMed2002

External cervical resorption associated with localized gingival overgrowth.

AIM: To describe the presentation and management of an unusual lesion of external cervical resorption. SUMMARY: The salient features of this unusual presentation of the external cervical resorption with localized gingival overgrowth, and the resorption located almost wholly on the labial aspect of a maxillary incisor crown are described. Extensive loss of enamel had occurred. The management and possible aetiology of the resorptive lesion are discussed. KEY LEARNING POINTS: Localized gingival overgrowth can be associated with external cervical resorption.The cervical resorption does not necessarily indicate pulp canal infection and the need for root-canal treatment.

Adult↗
PubMed2000

Missing upper lateral incisors: orthodontic considerations in young patients.

Missing lateral incisors are usually discovered by age 9 when general orthodontic treatment needs are becoming apparent. Whether to close, open or maintain a space for a missing lateral incisor is an orthodontic decision that needs to fit within a total plan of dental management. Factors to consider include:- Skeletal base relationship, severity of crowding, overjet, overbite, position into which the canine erupts, crown sizes, crown shapes, crown colours, gingival contours, gingival display on smiling, patient and parent attitude toward options, availability of appropriate prosthetic services, time delay before effecting "final" prosthetic treatment, space and bone required for implant fixtures and financial and biological costs.

Anodontia↗
PubMedDate not supplied

Early arrested development and coronal resorption of an impacted maxillary canine: report of case.

Coronal resorption of maxillary canines is a possible complication of long standing impaction. Degeneration of the enamel epithelium allows the connective tissues to come into direct contact with enamel. Irregular replacement of the pericoronal tissues and resorbed enamel by bone characterizes the histological picture. Inflammatory changes are rare. Resorption of enamel is slow and usually symptomless so that reported cases have usually been incidental radiographic findings in older patients. This report presents the early arrested development, ankylosis and resorption of the crown of a maxillary canine in a child 7.7-years-old. Arrest of crown development occurred between three and four-years-of-age. Radiographically the crown of the canine was incompletely formed and showed irregular resorption. Serial radiographs taken over a five-year period showed movement of the canine superiorly in relation to the hard palate which was taken as radiographic evidence for ankylosis of the resorbing maxillary canine in a growing child.

Ankylosis↗