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At least 577 records · Page 32Linked to original sources
PubMed1998

Unbiased stereological methods used for the quantitative evaluation of guided bone regeneration.

The present study describes the use of unbiased stereological methods for the quantitative evaluation of the amount of regenerated bone. Using the principle of guided bone regeneration the amount of regenerated bone after placement of degradable or non-degradable membranes covering defects in rabbit calvaria was compared. Forty rabbits were divided into 5 groups. A titanium microplate was placed over the defect to prevent collapse of the membrane. The non-degradable expanded polytetrafluoroethylene membrane and the degradable Polyglactin 910 material were both placed unicortically and bicortically. Undecalcified sections were prepared for stereologic evaluation after an observation period of 8 weeks. Complete bone healing of the defects was not observed in any of the specimens. Unbiased stereologic estimates revealed 48% bone regeneration in defects covered by 2 ePTFE membranes, and 12% in defects covered by 2 Polyglactin 910 membranes. Defects covered by 1 ePTFE or 1 Polyglactin 910 membranes revealed 10% or 18% bone regeneration, respectively. The control group regenerated 14%. The major difference of the estimates was caused by real difference between specimens, i.e. biologic variation, whereas only minimal variance was added by the stereologic estimation procedure.

Animals↗
PubMed1998

Measurements of bone and frame-work deformations induced by misfit of implant superstructures. A pilot study in rabbits.

This in vivo study used a 3-D photogrammetric technique to measure distortion of 3 unit implant frame-works and bone surrounding osseointegrated implants after securing misfitting superstructures to the implants. Four adult loop-eared rabbits were provided with 3 implants each in the proximal part of 1 tibia each. After a healing period of 8 weeks, a titanium frame-work was connected with a misfit to the central implant. Three-dimensional photographs were taken before and after securing the central screw, which induced a calculated mean preload of 246 N. Measurements and comparisons of the topography of the frame-works and surrounding bone before and after tightening the central screw indicated a complex and inconsistent deformation pattern. Generally, it could be observed that the top edge of the central cylinder showed vertical movement towards the bone of about 150 microns, always in combination with a rotation of the entire super-structure. The head of the central implant seemed to show a corresponding displacement towards the frame-work of about 50 to 200 microns. Bone deformation was found to be basically localized between the implants, where compressions of about half a millimetre were observed. This concentration of bone deformation as a result of misfit may be one contributing factor to initial marginal bone loss, occasionally observed after insertion of implant supported prostheses.

Animals↗
PubMed2002

Morphospatial analysis of soft-tissue profile in patients with Class II Division 1 malocclusion treated using twin block appliances: geometric morphometrics.

OBJECTIVES: To study soft-tissue profile changes in patients treated with twin block appliances (TBA) for the correction of Class II division 1 malocclusion. The null hypothesis is that soft-tissue profiles do not show any significant improvements associated with TBA treatment. DESIGN: Longitudinal, retrospective. SETTING AND SAMPLE POPULATION: Scotland, UK, using lateral cephalographs of 46 consecutive, prepubertal children (aged 9-11 years) and 55 adolescents (aged 12-14 years) obtained from an orthodontic practice. EXPERIMENTAL VARIABLE: The prepubertal children underwent = 13 months of TBA treatment, while the adolescents underwent = 22 months of treatment. OUTCOME MEASURES: Configurations of 13 digitized homologous landmarks of pre- and post-treatment soft-tissue facial profiles were compared using cephalometry, Euclidean distance matrix analysis (EDMA) and thin plate spline (TPS) analysis. RESULTS: Cephalometry showed that height increases associated with the TBA were in the labiomental areas, and the most significant height decreases were seen in the lip regions. The results of EDMA also indicated significant changes (P < 0.05). The distance between the lips decreased by >5%, with increases in length in the labiomental region. The TPS analysis showed the soft-tissues of the mandibular complex being displaced anteroinferiorly, with anterior displacement of the landmarks of the lip region. These changes showed that the lips were brought into closer proximity with each other, permitting a functional oral seal. Moreover, the labiomental groove became less pronounced, reflecting the underlying dento-alveolar correction. CONCLUSION: Demonstrable improvements in soft-tissue facial profile may be associated with TBA treatment.

Adolescent↗
PubMed1997

Reproducibility of optic nerve head topographic measurements with the glaucoma-scope.

PURPOSE: Glaucoma is an optic neuropathy in which optic nerve changes are important in diagnosis and progression, because the visual field may remain normal even while the optic nerve is undergoing significant damage. Accurate methods to objectively document the appearance of the optic nerve are necessary. In order for an optic disc imaging system to be clinically useful for detecting change, its reproducibility must be established. METHODS: We measured the reproducibility of duplicate measurements in 59 eyes of 31 consecutive patients, grouped into glaucoma subjects (n = 29) and eyes with glaucoma (n = 30), with the 3.10 OIS Glaucoma-Scope. In order to simulate two visits on one day, sets of three optic disc images were obtained first, followed by a repeat set, and the best disc images of each (chosen by the computer) were compared. RESULTS: The coefficients of variation of duplicate measurements for glaucoma suspects and patients with glaucoma were respectively: vertical cup/disc (c/d) ratio, 6.3% and 3.47%; horizontal c/d ratio, 4.61% and 2.97%; c/d area, 3.29% and 1.37%; cup area, 1.82% and 1.72%; mean position (MP) disc, 13.3% and 10.42%; MP total, 10.1% and 13.2%. For three eyes the examination was not possible (opacification of posterior capsule, miosis). CONCLUSION: These results suggest that the 3.10 version of the OIS Glaucoma-Scope allows reproducible measurements in living eyes.

Adult↗
PubMed1986

Stereophotogrammetry for measuring rates of cutaneous healing: a comparison with conventional techniques.

A portable stereocamera linked to a computer has been developed capable of taking photographs in the clinical situation. The accuracy and precision of this system has been measured and compared with direct tracing and simple photography, the two systems currently in use for this type of work. It was found to have a precision of better than 2% and to be accurate to within 1% for edge length and area in models of chronic leg ulcers whose dimensions were known exactly. These results are between five and ten times better than direct tracing and simple photography measured under similar circumstances. When used on patients' ulcers, stereophotogrammetry was found to have a precision of 2% for edge length and 3.4% for area, again between five and ten times more accurate than the other two systems. The accuracy with which an epithelial edge can be identified with the naked eye, a possible limiting factor in any visual measuring system, was measured on fixed preparations of healing wounds on pigs. The mean error was found to be 240 micron with a confidence limit of 440 micron. Finally, the rate of healing of chronic leg ulcers was measured in a clinical trial on patients. Only stereophotogrammetry had errors consistently smaller than the changes being measured in the clinical trial, making it the only system which can validly be used to study rates of healing in this model. It is also able to measure volume to within 5% and is unique in being able to do this noninvasively.

Clinical Trials as Topic↗
PubMed1995

Method for quantifying facial asymmetry in three dimensions using stereophotogrammetry.

A three-dimensional method to quantify facial asymmetry is introduced. Stereophotogrammetry was applied to determine three-dimensional (3-D) coordinates for eight pairs of surface landmarks of 106 individuals, including 16 with an operated complete unilateral cleft lip and palate. Facial asymmetry was quantified from four different reference planes that were defined perpendicular to and bisecting lines between pairs of bilateral landmarks related to the eyes, nose and mouth. Significant differences (P < 0.01) between these four planes were determined using multivariate analyses of variance (MANOVA). It is concluded that the best reference plane to select in studies of facial asymmetry is formed by the one which is perpendicular to and bisects the line that connects the landmarks Exocanthion. Reproducibility and validity of the method is demonstrated.

Child↗
PubMed1996

A comparison of three-dimensional and two-dimensional analyses of facial motion.

The purpose of this study was to compare the amplitude of facial motion obtained using three-dimensional (3-D) and two-dimensional (2-D) methods. The amplitude of motion of fifteen facial landmarks during five maximal animations (smile, lip-purse, grimace, eye closure, and cheek-puff) was quantified in 3-D and 2-D using a video-based system. Results showed that the 3-D amplitudes were significantly larger than the 2-D amplitudes, especially for landmarks on the lower face during the smile animation. In the latter instance, the 2-D amplitudes underestimated the 3-D amplitudes by as much as 43%. The difference between 3-D and 2-D amplitudes was greater for 2-D amplitudes obtained from one camera rather than from multiple cameras. The results suggest that a 2-D analysis may not be adequate to assess facial motion during maximal animations, and that a 3-D analysis may be more appropriate for detecting clinical differences in facial function.

Adult↗
PubMed1996

Reliability of a three-dimensional method for measuring facial animation: a case report.

Reliable methods of quantifying functional impairment of the craniofacial region are sorely lacking. The purpose of this study was to test the reliability of a three-dimensional method for assessing the functional repertoire of the face. Subjects were instructed to perform repeated sequences of five maximal facial animations. Facial motions were captured by three 60-Hz video cameras, and three-dimensional maximum motion amplitudes were calculated. Student's t-test and Pearson product-moment correlation coefficients were used to test for significant differences between repetitions. The results show moderate to excellent reliability of the amplitude of motion for the landmarks over all animations. For each specific animation, certain landmarks demonstrated excellent reliability of motion.

Adult↗
PubMed2006

Sagittal spinal posture in relation to craniofacial morphology.

OBJECTIVE: The aim of this study is to determine correlations between the parameters of body posture in the sagittal profile and sagittal jaw position by obtaining objective and valid three-dimensional measurements of the dorsal profile by means of rasterstereography. MATERIALS AND METHODS: Fifty-three adults with Class II or III malocclusions were examined, and six angular parameters were determined. For the sagittal analysis of body posture, the Fleche Cervicale and Lombaire as well as trunk inclination were evaluated. RESULTS: Statistically significant correlations (P < .05) were found between Facial Axis and Fleche Cervicale, Mandibular Plane angle and Fleche Cervicale, and Facial Depth and the Fleche Cervicale. CONCLUSIONS: It can be concluded that the mandible seems to have a greater effect on body posture than other craniofacial parameters. As a clinical result of this study, patients with severe malocclusions should be examined interdisciplinarily before orthognathic surgery is performed to minimize postural influence on the altered jaw relationship after surgery.

Adult↗
PubMed2006

Relationship between thoracic, lordotic, and pelvic inclination and craniofacial morphology in adults.

OBJECTIVE: To analyze the correlation ratios between the spinal posture (thoracic, lordotic, and pelvic inclination) and the craniofacial morphology. MATERIALS AND METHODS: The sample consisted of 53 healthy adults (32 women, 21 men; mean age 24.6 years). Six angular skeletal measurements (facial axis, mandibular plane angle, inner gonial angle, lower facial height, facial depth, and maxilla position) were determined based on the analysis of lateral head cephalographs. Rasterstereography was used for a precise reconstruction of the back sagittal profile. From the profile parameters, the upper thoracic inclination, the thoracic angle, the lordotic angle, and the pelvic inclination were determined. The correlations to the craniofacial morphology were calculated by means of the Pearson and Mann-Whitney U-test. RESULTS: Significant correlations could be obtained with respect to the facial axis and the lordotic angle, the facial axis and the pelvic inclination, the inner gonial angle and the lordotic angle, the inner gonial angle and the pelvic inclination, the mandibular plane angle and the lordotic angle, the mandibular plane angle and the pelvic inclination, as well as the facial depth and the pelvic inclination. CONCLUSIONS: In the case of postural disorders of the back shape, an interdisciplinary treatment approach seems to be of clinical value. Further prospective studies are necessary to prove how changes in craniofacial parameters can affect the postural balance of an individual.

Adult↗
PubMed1998

Smoking and vascular density of healthy marginal gingiva.

The influence of smoking on the vascular characteristics in periodontally healthy individuals was studied over a period of 11 wk. Fourteen healthy female dental students, 7 smokers and 7 nonsmokers, aged 25 to 38 yr, volunteered for the experiment. Photodocumentation was performed on four occasions with the aid of a stereophotographic method. The characteristics of gingival vessels were evaluated according to a semi-quantitative vascular index. It was found that the vascular density was not statistically significantly different in smokers and nonsmokers. Furthermore, the vascular density remained stable in both smokers and nonsmokers. The results suggest that the vascular density of the marginal gingiva is uninfluenced by moderate smoking once healthy gingival conditions prevail.

Adult↗