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Incisal Edge (incisal + edge)
Selected AbstractsMicrocephalia with mandibular and dental dysplasia in adult Zmpste24-deficient miceJOURNAL OF ANATOMY, Issue 5 2008F. De Carlos Abstract ZMPSTE24 (also called FACE-1) is a zinc-metalloprotease involved in the post-translational processing of prelamin A to mature lamin A, a major component of the nuclear envelope. Mutations in the ZMPSTE24 gene or in that encoding its substrate prelamin A (LMNA) result in a series of human inherited diseases known collectively as laminopathies and showing regional or systemic manifestations (i.e. the Hutchinson,Gilford progeria syndrome). Typically, patients suffering some laminopathies show craniofacial or mandible anomalies, aberrant dentition or facial features characteristic of aged persons. To analyse whether Zmpste24,/, mice reproduce the cranial phenotype observed in humans due to mutations in ZMPSTE24 or LMNA, we conducted a craniometric study based on micro-computer tomography (µCT) images. Furthermore, using simple radiology, µCT, µCT-densitometry and scanning electron microscopy, we analysed the mandible and the teeth from Zmpste24,/, mice. Finally, the structure of the lower incisor was investigated using an H&E technique. The results demonstrate that Zmpste24,/, mice are microcephalic and show mandibular and dental dysplasia affecting only the mandible teeth. In all cases, the lower incisor of mice lacking Zmpste24 was smaller than in control animals, showed cylindrical morphology and a transverse fissure at the incisal edge, and the pulpal cavity was severely reduced. Structurally, the dental layers were normally arranged but cellular layers were disorganized. The inferior molars showed a reduced cusp size. Taken together, these data strongly suggest that Zmpste24,/, mice represent a good model to analyse the craniofacial and teeth malformations characteristic of lamin-related pathologies, and might contribute to a better understanding of the molecular events underlying these diseases. [source] Direct versus Indirect Veneer Restorations for Intrinsic Dental StainsJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2006Article first published online: 25 APR 200 abstract Objective:, The purpose of this study was to examine the effectiveness of indirect and direct veneer restorations, particularly with regard to longevity and patient satisfaction. Materials and Methods:, This study evaluated the literature on randomized clinical trials comparing direct and indirect veneers on anterior teeth. The search strategy involved Medline and other databases and was followed by contacting authors to determine whether any additional published or unpublished studies were available. Relevant studies were assessed for factors such as quality of randomization, outcome assessment, and completeness of recall evaluation. Data from the studies were extracted by three independent reviewers using special forms. Authors were contacted for clarification and missing data. Study details such as dates, demographics of the sample, and outcomes were recorded. Results:, The electronic searches identified 29 clinical trials and 1 systematic review. Six of those were screened as potentially relevant to the review, but following a more detailed screening, only one study (Meijering and colleagues, 1998) met all of the inclusion criteria. In the 2-year recall of that study, the overall survival rates were 94% for porcelain, 90% for indirect composite, and 74% for direct composite veneers. The survival rate was higher when the incisal edge was reduced. Patient satisfaction rates were 93% for porcelain, 82% for indirect composite, and 67% for direct composite. Conclusion:, Very little reliable evidence compares the effectiveness of indirect versus indirect veneers. For an individual patient, the choice between the two options should take into account patient preference and the clinician's experience. [source] An in vitro assessment of the strength of porcelain veneers dependent on tooth preparationJOURNAL OF ORAL REHABILITATION, Issue 12 2000P. Hahn The treatment of teeth using veneer restorations combines aesthetic and functional improvements with a low destructive technique. Different kinds of tooth preparation techniques are described in the literature for this kind of restoration. This in vitro study aimed to examine the influence of the incisal preparation on the loadability of teeth restored with porcelain laminate veneers. Thirty-six selected mandibular incisors were randomly assigned to three groups with 12 teeth per group. In the first group, only the facial surface was prepared. In the second group, the preparation included a rounded incisal edge and a distinct chamfer lingually. The third group served as an unprepared control. Empress® veneers were then fabricated and cemented with a low viscous luting composite material. After 120 days storage in Ringer's solution, the specimens were loaded incisally to the point of failure. Statistical analysis of the results showed significant differences between the series (P=0·0103). Group 2 (with preparation of the incisal edge) exhibited the lowest fracture resistance (466±99 N) (N, mean forces). When prepared only facially, the teeth restored with Empress® veneers reached the strength of unprepared teeth. Compared with the biting force described for incisors in the literature, the in vitro loadability reached in this investigation seems to jusitify the clinical use of both preparation designs tested. [source] Dental erosion in Cuban children associated with excessive consumption of orangesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2000Walter Künzel Marked erosion at the mesial edges of upper front teeth was observed during an examination of Cuban children. The preferential erosion of mesial edges produced characteristic V-shaped defects on upper central incisors, and the aim of the present study, carried out on 12-yr-old children (N=1010) in 10 communities in the Province of Havana was to establish the frequency of dental erosion and explain its occurrence. The symmetrical erosion of teeth 11 and 21 (excluding crown injuries and attrition) were clinically classified into four grades: 0.5=objectionable; 1=abnormal mesial shortening of incisal edges; 2=V-shaped defect of cutting edges; 3=exposure of dentine and extension of the erosive defect to the lateral incisors. In four of the communities, children did not show or rarely showed incisal erosion. In the other six communities, the frequency was surprisingly high (16.6,40.9%). Overall, 17.4% of children exhibited erosion, and the occurrence was significantly higher in girls (20.7%) than in boys (15.0%). The typical V-shaped pattern of erosion seems to be a consequence of the manner in which citrus fruits are eaten. There was also a positive correlation between the frequency of dental erosion and the proximity of citrus plantations, which presumably related to the extent of (daily) orange consumption. [source] Digital Analysis of Experimental Human Bitemarks: Application of Two New MethodsJOURNAL OF FORENSIC SCIENCES, Issue 6 2006Nazar Al-Talabani B.D.S., Ph.D. ABSTRACT: Bitemark determination in forensic odontology is commonly performed by comparing the morphology of the dentition of the suspect with life-sized photographs of injury on the victim's skin using transparent overlays or computers. The purpose of this study is to investigate the suitability of two new different methods for identification of bitemarks by digital analysis. A sample of 50 volunteers was asked to make experimental bitemarks on the arms of each other. Stone study casts were prepared from upper and lower dental arches of each volunteer. The bitemarks and the study casts were photographed; the photos were entered into the computer and Adobe Photoshop software program was applied to analyze the results. Two methods (2D polyline and Painting) of identification were used. In the 2D polyline method, fixed points were chosen on the tips of the canines and a straight line was drawn between the two fixed points in the arch (intercanine line). Straight lines passing between the incisal edges of the incisors were drawn vertically on the intercanine line; the lines and angles created were calculated. In the painting method, identification was based on canine-to-canine distance, tooth width and the thickness, and rotational value of each tooth. The results showed that both methods were applicable. However, the 2D polyline method was more convenient to use and gave prompt computer-read results, whereas the painting method depended on the visual reading of the operator. [source] | ||||||||||