Fusion and gemination of permanent teeth are developmental anomalies of the dental hard tissues which may require endodontic and surgical treatment for functional, orthodontic or aesthetic reasons. Following a review of the dental literature on tooth fusion and gemination, a case of fusion of a maxillary central incisor and a supernumerary tooth and its endodontic and surgical treatment is presented.
Background and Purpose-The vasomotor response can be tested by means of transcranial Doppler sonography. If a constant vessel diameter is assumed, the flow velocity changes will reflect blood flow volume changes. This hypothesis is difficult to verify. Simultaneous assessment of intracranial flow velocity and extracranial flow volume changes may solve this problem. Methods-We tested vasomotor response in 32 volunteers (age, 42Ϯ18 years) with 5% CO 2 . Acetazolamide (1 g) was tested in 15 volunteers (age, 28Ϯ8 years). To evaluate drug-dependent flow changes in the external carotid artery territory, acetazolamide was administered in 7 patients with unilateral occlusion of the internal carotid artery without evidence of collateralization through the ophthalmic artery (age, 67Ϯ12 years). Simultaneous recording included measurements of flow volume in the common carotid arteries (M-mode color duplex system) and flow velocity in the middle cerebral arteries. Results-With CO 2 and acetazolamide, intracranial flow velocity increased by 31% and 39%, respectively, with a simultaneous increase of common carotid artery flow volume of 47% and 50%, respectively. No change in extracranial flow volume was observed in patients with an occluded internal carotid artery. Conclusions-These data show not only the expected increase of flow velocity in the middle cerebral artery but also suggest an increase in cross-sectional vessel diameter of 6% and 4% with CO 2 and acetazolamide, respectively. It remains unresolved whether this observation is due to a direct effect of the drug on the vessel walls or is simply pressure dependent. (Stroke. 1999;30:76-80.)
The aim of this study was to evaluate several parameters for automated root canal preparation with the Excalibur handpiece compared with hand instrumentation. The parameters investigated were straightening of curved canals, cleaning ability, working safety (loss of working length, instrument separation, perforation), cross sectional diameter before and after enlargement, and working time. Sixty curved root canals were prepared using the Excalibur handpiece and 30 curved canals with conventional hand instruments to ISO-size 35. The Excalibur left significantly less debris and smear layer on the root canal walls, but hand preparation resulted in fewer unprepared regions. Root canal curvature was well maintained by either technique; the degree of straightening depended on original root canal curvature rather than on the preparation technique. The Excalibur removed significantly more dentin. In the coronal part of the root canal, hand instruments produced significantly more round and oval cross sections; in the middle and apical part no differences could be detected. Working time was shorter for hand preparation, but the difference was not significant. Manual instrumentation proved to be safe; no instrument fracture, perforation or loss of working length could be observed, whereas automated preparation resulted in one perforation and two cases of loss of working length.
The intracranial effects of acetazolamide on flow velocities can be monitored noninvasively by transcranial Doppler (TCD) sonography. Extracranial volume flow changes can now reliably be measured with color duplex M-mode systems. The authors tested the volumetric effects of acetazolamide in patients with high-grade unilateral carotid disease to quantify the amount of flow changes. Patients in group 1 had a high-grade > 70% internal carotid artery (ICA) stenosis, without collateral flow through the ophthalmic artery (OA). Patients with occluded ICA were included in group 2 (patent OA collateralization) or group 3 (no OA collateralization) (n = 6 per group). In group 1, common carotid artery (CCA) volume flow in the stenotic (normal contralateral) side increased from 271 (388) ml/min by 52 (54%) with 1 g aceta-zolamide intravenously. Simultaneously, middle cerebral artery (MCA) flow velocities increased from 54 (56) cm/s by 47 (53%). In group 2, extracranial volume flow increased from 166 (444) ml/min by 19 (52)%. MCA flow velocities increased from 43 (65) cm/s by 13 (30)%. In group 3, volume flow increased from 159 (467) ml/min by 2 (46)%. Intracranial flow velocities rose from 49 (54) cm/s by 27 (41)%. Volume flow data showed the expected decline in patients with high-grade ICA stenosis and even more pronounced in patients with occlusion of the vessel. Cerebral reserve capacity was less sufficient in patients with a patent OA, despite an additional supply of 30 ml/min, indicating a hemodynamically critical situation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.