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At least 163 records · Page 9Linked to original sources
PubMed1990

[Comparative studies of the prognosis of supporting areas].

After measuring average supporting zones in the deciduous and permanent dentition the "leeway space" is determined. The prognostic value of three methods is compared with the average supporting zones in the eugnathic permanent dentition. Separate measurements for the upper and lower jaw in the male and female were done. Correlations between early erupted teeth were considered in the prognosis of the size of the supporting zones. Prognostic values differ, they could be smaller, of equal size or larger compared with the average supporting zones. Average discrepancies range from 0 mm to 1.04 mm. Individual differences are larger amounting up to 3.24 mm. The average differences, but not the individual ones are probably only relevant in important clinical areas.

Adolescent↗
PubMed1993

[3-dimensional computed tomographic imaging of the dentate alveolar ridge. A radiological-histological comparison].

Human bone segments of the toothed jaw with ten upper and ten lower teeth were scanned by high resolution computer tomography in continuous parallel axial and coronal slices (Somaton plus, Siemens). In both directions scanning was performed to 1 mm and 2 mm thicknesses and at 1 mm and 2 mm intervals. The jaw segments were dissected analogously in 1 mm thick slices. Contact films of the corresponding bone segments were exposed and then histological thin sections prepared. The statistical comparison between the CT exposures, the contact films, and the histological sections revealed an average absolute deviation of 0.3 to 0.5 mm with the axial CT exposures and a deviation of 0.3 to 1.6 mm with the coronal sections. It was possible to interpret in a quantitatively detailed manner the teeth and surrounding bone compacta up to a 0.5 mm minimum bone thickness. Computer-enhanced secondary reconstructions made possible an additional qualitative interpretation of the bone upper surface and the freely definable planes. Continuous parallel axial CT slices enable an interference-free, proportionally accurate representation of the apical base, the periodontal bone structure, and the radice-root topography.

Adult↗
PubMed1989

[Recent comparative statistical correlation studies on predicting the space requirement of the cuspid and bicuspid region using multiple regression comparisons].

The purpose of the investigation was to develop multiple regression equations to calculate the space requirements in the canine and premolar regions. The investigation was based on study models from a group of 63 (36 males and 27 females) patients with an ideal Angle class I occlusion. The mesiodistal width of unerupted incisors and the buccolingual and mesiodistal width of first molars were used as independent variables. A test group of 64 study models (32 males and 32 females) from orthodontically treated patients was used to represent the malocclusions typically present in an orthodontic clinic or practice. The space requirement can be predicted from three variables in both upper and lower jaws. The inclusion of more variables does not significantly improve the prediction. The correlation coefficient for the buccolingual width of the first lower molar was significantly higher than that for the mesiodistal width. The combination of 22, 32 and 36 (buccolingual) achieved the highest correlation coefficient in both groups. Further, if at the time of analyses, one of the canines or premolars (33, 34 or 24) has erupted their width may be included as an additional independent variable. The correlation and regression coefficients for males and females showed no significant difference.

Bicuspid↗
PubMed1994

[A dental arch index related to tooth size and facial breadth].

Taking as its starting point the often postulated criticism of Pont's Index, the intent of the study was to develop a diagnostic procedure which took into consideration the objection that the Pont Index doesn't take the shape of the patient's skull into consideration. On the basis of the data obtained from the models and anthropological measurements of 50 adult subjects with fairly eugnathic dentition, the first step was to follow Pont and study which skull size exhibited the highest correlation to the posterior dental arch. Of all the relevant sizes the zygomatic arch width exhibited the highest correlation. Reference values for the posterior dental arch width, which were obtained with the help of regression analysis, which took into consideration both the total upper incisor width and zygomatic arch width as variables, were then established. These reference values were conclusively shown to have the best prognostic value. From this it can be concluded that a comprehensive orthodontic diagnosis should include an improved assessment of dental arch width.

Adult↗
PubMed2005

Determining skeletal parameters in angle classes II, division 1 and II, division 2.

AIM: Aim of the study was to find out whether significant differences in skeletal morphology exist between Angle Class II, Division 1 and II, Division 2. MATERIAL AND METHOD: Fifty-nine patients without previous orthodontic treatment showing Class II occlusion and distobasal jaw relation were evaluated by cephalometric analysis. RESULTS: Significant differences existed in skeletal morphology between patients with Angle Class II, Division 1 and II, Division 2, with only minor gender-specific differences: angleML/NSL in Class II, Division 2 males (p < 0.01) and females (p < 0.05) was smaller compared to Class II, Division 1 patients. angleML/NL was also noticeably smaller in Class II, Division 2 males (p < 0.001) and females (p < 0.01) compared to Class II, Division 1 patients. Patients with Class II, Division 2 had a smaller gonial angle (angleArGoMe), with the difference being significant only in males (p < 0.05).

Adolescent↗
PubMed1998

Otodental syndrome, oculo-facio-cardio-dental (OFCD) syndrome, and lobodontia: dental disorders of interest to the pediatric radiologist.

Three unusual dental anomalies are presented which should be of interest to the pediatric radiologist: otodental syndrome - an autosomal dominant syndrome of bizarre, greatly enlarged teeth with bulbous crowns (globodontia) that spares the incisors, in combination with sensorineural hearing loss; oculo-facio-cardio-dental syndrome - an X-linked dominant syndrome that is lethal in males, characterized by congenital cataracts, unusual facies, atrial septal defect (ASD), ventricular septal defect (VSD), and canine teeth that cease to grow only when they cut off their own blood supply by growing through the orbit and lower border of mandible; and lobodontia - a dominant disorder characterized by teeth whose crowns resemble those of a wolf.

Abnormalities, Multiple↗
PubMed2006

3-D imaging and quantitative comparison of human dentitions and simulated bite marks.

This study presents a technique developed for 3-D imaging and quantitative comparison of human dentitions and simulated bite marks. A sample of 42 study models and the corresponding bites, made by the same subjects in acrylic dental wax, were digitised by laser scanning. This technique allows image comparison of a 3-D dentition with a 3-D bite mark, eliminating distortion due to perspective as experienced in conventional photography. Cartesian co-ordinates of a series of landmarks were used to describe the dentitions and bite marks, and a matrix was created to compare all possible combinations of matches and non-matches using cross-validation techniques. An algorithm, which estimated the probability of a dentition matching its corresponding bite mark, was developed. A receiver operating characteristic graph illustrated the relationship between values for specificity and sensitivity. This graph also showed for this sample that 15% of non-matches could not be distinguished from the true match, translating to a 15% probability of falsely convicting an innocent person.

Australia↗
PubMed2002

Patterns of third molar impaction in a group of volunteers in Turkey.

The aim of this study was to investigate the different variables in mesio-vertically positioned impacted or erupted third molars in a group of volunteers in Turkey to determine the angular changes and levels of eruption radiographically using standardised panoramic radiographs. There were 213 volunteers with impacted and erupted third molars included in this study, most of whom were dental students. Standardised panoramic radiographs were taken from all the volunteers. The radiographic parameters included angulation of tooth, level of eruption, development of root, mesiodistal crown width, retromolar space, and gonial angle. Statistical analysis was done using the t-test for independent groups. It was found that the mesiodistal angulation of third molars was significantly greater while the retromolar space of third molars was significantly smaller in the impacted group (P<0.05). There was also a significant difference in retromolar space/third molar crown width ratio (P<0.05).

Adolescent↗
PubMed2002

Assessment of root curvature and distance using computed tomography.

The safety and efficacy of subgingival root surface instrumentation may be enhanced by optimized adaptation between instrument and treated surface. Thus, detailed knowledge of root geometry may allow advances in instrument design. The aim of this study was therefore to measure root radii of various tooth types as well as distances between tooth roots using computed tomography. Two hundred sixteen teeth in eight patients were studied, with cross sections of teeth at the level of the cemento-enamel junction (CEJ) being regarded as ellipses. The maximum radii of ellipses were calculated and averaged for each tooth surface within various tooth groups. In addition, the spacing between roots at CEJ level and 5 mm below the CEJ was measured. Mean radii varied from 1.09+/-0.50 mm (lower incisor, lingual) to 13.7+/-0.96 mm (upper molar, mesial). Radii of 1 mm to 6 mm were most frequently found at buccal, palatal, and lingual surfaces, whereas the majority of radii were between 2 mm and 11 mm at mesial and distal sites. Root distance varied between 1.04+/-0.49 mm (lower incisors, CEJ level) and 2.81+/-1.70 mm (lower molars, 5 mm below CEJ). The curvature of an instrument for root surface instrumentation should correspond to a radius of at least 11 mm to achieve maximum adaptation to the treated surface, and the width of the working end should be less than 1 mm to allow sufficient interdental instrumentation.

Adult↗
PubMed2006

Volumetry of human molars with flat panel-based volume CT in vitro.

The flat panel-based volume computed tomography (fpVCT) is a new CT device applicable for experimental, three-dimensional evaluation of teeth at a resolution of about 150 microm in the high contrast region. The aim of this study was to investigate whether fpVCT was suitable for quantification of the volumes of dental hard tissues and the root canal system to establish a new method for morphological studies. Fifty-two extracted third molars (maxillary: 31, mandibular: 21) were examined with a prototype of an fpVCT using a volumetry algorithm at different levels according to the radiographic density of enamel and dentine. Volumetry of the root canal system was performed after "region growing segmentation": starting from a voxel in the centre of the root canal, this algorithm searches voxels of same density in the surrounding. The volumetry of the root canal system was stopped by the investigator at the apical constriction. Results showed that dentine, enamel and root canal system could be well distinguished in three-dimensional images. Volumetry yielded the following data (cm(3), mean+/-SD): dentine 0.438+/-0.111, enamel 0.227+/-0.051, root canal system 0.052+/-0.017 and total volume 0.753+/-0.159. In conclusion, the fpVCT is appropriate for non-destructive volumetry of large numbers of teeth in experimental laboratory studies.

Absorptiometry, Photon↗
PubMed2006

Electronic root canal length measurement before and after experimentally induced pulpitis and apical periodontitis in dogs.

The aim of the study was to examine the influence of the state of the pulp and apical periodontium on the results of electronic root canal length measurement (ERCLM) with a resistance measuring device in dogs. Pulpitis and apical periodontitis were induced by pulp exposure and contamination by the oral flora in the premolar teeth of six mongrel dogs, comprising four experimental groups (36 root canals). In a control group, measured lengths of teeth with uninfected pulps were performed on the first experimental day (44 root canals). In all animals the ERCLMs were performed on teeth with healthy pulps, and at the end of the experimental period (20, 35, 50 and 65 days) following pulp exposure. The point of measuring canal lengths was the anatomical obstacle above the apical delta. Electronically measured lengths (EML) were compared between each other and with the root canal length established by tactile-sense measurement verified radiographically. The EMLs were less accurate in teeth with healthy pulps and teeth with pulpitis in the third experimental group (dif=2.27 x 2.65 mm(2); t test, p<0.05), while they were most precise after 65 days in teeth with completely necrotic pulp and established chronic apical periodontitis (dif=0.54 x 1.36 mm(2); t test, p>0.05). These results suggest that the state of the pulp and periapical tissue may have an influence on the ERCLM.

Animals↗