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Two lingual root structures are occasionally found on human permanent maxillary molars. One of these is the normal lingual root, which is always present, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis (RML)) or distolingually (radix distolingualis (RDL)). The available literature refers only to the existence and location of RML and RDL Very small materials have, quite simply, hitherto precluded a more detailed description of these roots. The large collection of extracted teeth at the School of Dentistry in Copenhagen now includes a non-random subcollection of 145 permanent maxillary molars, the root complex of which contains 2 lingual root structures. Based on this material it was possible to undertake a modern, systematic analysis of the macromorphological variation of RMLs and RDLs. In this study, which was mainly non-metric, criteria for the identification of RML and RDL were established. The analysis also showed that the lingual supernumerary roots were only rarely found on the first molar, but with increasing frequency on the second and third molars. Both separate and non-separate RML and RDL were observed. In the material, degrees of separation greater than 0.9 were registered, degrees of divergence up to approximately 45 degrees, an apical bend of approximately 90 degrees, and extreme apical slenderness. Even though the supernumerary roots described here do not occur very often, knowing about them is nevertheless clinically relevant in for example endodontic and surgical contexts. [ABSTRACT FROM AUTHOR]

This report is the conclusion of the international consensus committee on renal transit time (subcommittee of the International Scientific Committee of Radionuclides in Nephrourology) and provides recommendations on measurement, normal values, and analysis of clinical utility. Transit time is the time that a tracer remains within the kidney or within a part of the kidney (eg, parenchymal transit time). It can be obtained from a dynamic renogram and a vascular input acquired in standardized conditions by a deconvolution process. Alternatively to transit time measurement, simpler indices were proposed, such as time of maximum, normalized residual activity or renal output efficiency. Transit time has been mainly used in urinary obstruction, renal artery stenosis, or renovascular hypertension and renal transplant. Despite a large amount of published data on obstruction, only the value of normal transit is established. The value of delayed transit remains controversial, probably due to lack of a gold standard for obstruction. Transit time measurements are useful to diagnose renovascular hypertension, as are some of the simpler indices. The committee recommends further collaborative trials.

Aim: The aim of this study was to design a general nuclear medicine method for fast, accurate and direct determination of the clearance of a radioactive indicator provided that all uptake compartments of the radioactive indicator could be included in the field of view of the gamma camera., Methods: The data material for clearance calculation in the gamma camera method (GCM) comprises: (1) a transmission map of a part of the body using a water filled flood field phantom with a uniform distribution of the radioisotope, (2) the background corrected activity curves in the anterior and posterior views over all uptake compartments following the injection of the radioactive indicator, and (3) the activity of the radioactive indicator in at least two blood samples drawn during the examination. With a view to determining glomerular filtration rate (GFR) in 99mTc-DTPA renography the gamma camera method was tested in a group of 26 adult subjects in whom GFR was determined simultaneously using the simplified multiple samples method (MSM) with plasma samples drawn 3-5 h following the injection of 51Cr-EDTA., Results: For values of GFR above 30 ml.min(-1) the regression line of GFR in the MSM versus GFR in the GCM was not significantly different from the line of identity. The reliability of the GCM alone was about 14%, 11% and 6% for GFR values of 30, 60 and 120 ml.min(-1) and, therefore, the reliability of the GCM and the simplified MSM for prediction of GFR was almost the same., Conclusion: Since the recording of the renal count rates in the anterior and posterior views permits an accurate determination of the split renal function, the GCM yields reliable estimates also of the single kidney GFR.

The School of Dentistry in Copenhagen possesses a collection of 96 human permanent maxillary molars (M sup) with a root complex, the macromorphology of which includes a facially located supernumerary root known as radix paramolaris (RP) and/or a distally located supernumerary root called radix distomolaris (RD). Systematic analysis of these teeth enabled the authors to establish precise criteria for the identification of RP and RD on M sup; 91.5% out of a total of 70 RP identified occurred on M3 sup, 7.2% on M2 sup, and 1.4% on M1 sup. The corresponding percentages for 29 RD identified were: 96.5% on M3 sup, 3.4% on M2 sup, and 0.0% on M1 sup; 50.0% of the 70 RP were separate in relation to the 2 facial root components and 31.5% non-separate; in 18.6% of the RP observed, it was impossible to establish whether or not they were separate. Corresponding frequencies for the 29 RD in relation to the distofacial and lingual root components were 41.3% separate and 37.9% non-separate; 20.7% of the roots could not be categorized. The following clinically relevant macromorphological variables regarding RP and RD were also observed: degree of separation in relation to the respective neighboring root components, degree of divergence in relation to the same macrostructures, apical bend, apical gracility, and pattern of fusion.

The aim of this study was to register the root canal number, root canal position, and root canal cross-section in human two-rooted, permanent maxillary second molars. One hundred and fifty-nine such teeth extracted in Denmark were cross-sectioned at the mid-root level and apically in accordance with precise guidelines. The observations were made in a stereomicroscope, corresponding to the above-mentioned section levels. At mid-root there were two canals present in 11% of the teeth examined; the canals were located mesially and distofacially, mesiofacially and distally, or facially and lingually. Three canals positioned mesiofacially, distofacially, and lingually were observed in 89% of the teeth. At the same level 62% of the canal cross-sections were noncircular, some being, for instance, C-shaped, whereas 38% of the cross-sections were circular. Apically, two canals were found, representing 19% of the teeth, with the canal position as at mid-root; 81% of the teeth were three-canaled with the same canal position as at mid-root. At the apical level 60% of the canal cross-sections were noncircular, whereas 40% of the cross-sections were circular.

The Ekman-Westborg-Julin Syndrome is reveiwed and a new case reported.

The authors present a method for differentiating between human mandibular premolars: P1 inf and P2 inf. The material with which the method was developed consisted of 260 stone casts. On these, both premolars were present and were intact on at least one side. The study models represented 131 girls and 129 boys, mean age 14.6 yr. In a comprehensive pilot project, a whole range of macromorphologic criteria was tested that, in various combinations, could be expected to be usable for differentiation between P1 inf and P2 inf. On the basis of the pilot study, the total variation was reduced to four criteria-combinations, called types, which, in summary, can be characterized as the following: type 1: flattening of the mesiolingual part of the crown, no lingual lobe; type 2: at least one lingual lobe; type 3: lingual part of the crown symmetrically curved, no lingual lobe; type 4: other characteristics. After definition of the types, their occurrence on P1 inf and P2 inf was definitively registered. Observations were made with a stereomicroscope; 131 premolar pairs from the right side and 129 from the left were registered. Statistical tests showed that there was no significant difference in the distribution of types between variants from the right and left sides, or between girls and boys. These data were therefore pooled for P1 inf and P2 inf, respectively. A subsequent test revealed, as expected, a highly significant difference in the distribution of the four types among 1. and 2. premolar.(ABSTRACT TRUNCATED AT 250 WORDS)

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth extracted in Denmark. The collection currently contains 104 one-rooted, permanent maxillary second molars. The root complex on these teeth was sectioned at the junction between the coronal and the apical halves, i.e. mid-root, and at the junction between the middle and the apical thirds, i.e. apically. Using a stereomicroscope we then registered, mid-root and apically, the following variables: canal number, canal position, and canal cross-section. Mid-root there was 1 centrally located root canal in 25.96% of the teeth examined; 2 canals were observed either mesially and distofacially, mesiofacially and distally, or facially and lingually in 34.62%; 3 canals positioned mesiofacially, distofacially, and lingually were found in 39.42%. At the same level 63.51% of the canal cross-sections were non-circular, whereas 36.49% of the canals had a circular cross-section image. The non-circular canal cross-sections could more specifically be characterized as C-shaped, Y-shaped, hourglass-shaped or the root canal had a greater faciolingual than mesiodistal extension or, respectively, a greater mesiodistal than faciolingual extension. Apically there was 1 centrally located root canal in 35.58%; 2 canals were observed with a position either mesially and distofacially, mesiofacially and distally, or facially and lingually in 37.49%; 3 canals located mesiofacially, distofacially, and lingually were found in 26.92%. At the apical level, 64.32% of the root canal cross-sections were non-circular, whereas 35.68% of the canals showed a circular cross-section. The results presented here are aimed at: clinical dentists, endodontists, and dental morphologists.

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth which have been extracted in Denmark. The collection presently includes 203 permanent mandibular molars with a root complex containing a facially-located supernumerary root. This macrostructure is named radix paramolaris (RP). By analyzing the large number of specimens available it was possible to establish uniform and precise criteria for the identification of RP on M1 inf, M2 inf, and M3 inf. The analyses included both separate and non-separate RP. The representation of the RP variants according to tooth type was mapped. Furthermore, the following clinically relevant variables with respect to RP were registered: degree of separation, divergence, apical bend, apical gracility, and fusion. Because of the nature of the material, the study was mostly qualitative and non-metric. The results are aimed primarily at clinical dentists, dental morphologists, and dental anthropologists.

Based on serially cut 200-microns-thick sections from 21 human mandibular third molars, a quantitative characterization was made of the morphology in the mesial and distal interlobal groove. Two parameters were used: depth of interlobal groove and structure angle. The interlobal groove depth varied between 0.13 and 0.55, taken in relation to the maximum crown height. The structure angle varied between 2 degrees and 170 degrees. If the structure angle was less than or equal to 25 degrees, the interlobal groove was classified as a fissure; if the angle was greater than 25 degrees, the interlobal groove was classified as a groove. Only in 18% of the sections did the interlobal groove manifest itself as a fissure. The study demonstrates that it was possible unambiguously to describe the two-dimensional profile of interlobal grooves by groove depth and structure angle.

The Royal Dental College, Copenhagen, houses an extensive collection of human teeth, extracted in Denmark. At present, the collection includes 398 permanent mandibular molars with a root complex containing a lingually-located supernumerary root. This macrostructure is called radix entomolaris (RE). By analyzing the large number of available specimens it was possible to establish uniform and precise criteria for the identification of RE on M1 inf, M2 inf, and M3 inf. The analyses included separate as well as non-separate RE. The representation of the RE variants according to tooth types was mapped. Furthermore, the following relevant clinical variables with respect to RE were registered: degree of separation, divergence, apical bend, apical gracility, and fusion. Because of the nature of the material, the investigation was mostly qualitative and non-metric. The results should be of interest to clinical dentists, dental morphologists, and dental anthropologists.

The principal aim of this investigation was to verify an expected, probable correlation between certain variables, which are initially represented in the macrostructure of the root complex corresponding to the cemento-dentin junction, and certain variables that subsequently manifest themselves in the root canal system. A material consisting of 76 one-rooted, permanent mandibular second molars (M2 inf) was used. The specimens were cut at the mid-root level and all observations were made on the coronal root segment using a stereomicroscope. Relevant variables of the root complex were observed. The total macromorphologic variation of the root complex could be subdivided and classified in well-defined, distinguishable types. In accordance with the single root complex type an expected, logically deduced configuration of the root canal system was established. The relevant variables of the canal system were then recorded. Finally, the root complex morphology, as well as the expected and actually observed canal configuration, were compared type by type. In 76.3% of the teeth a good concordance could be shown between the expected and the actual canal configuration, whereas in 23.7% of the specimens there was a divergence. In 42.1% of the investigated teeth, 1 centrally localized main canal with varying cross section images, among them a C-shaped image, was found. In 30.3%, 2 main canals were found, which were often localized mesially and distally. In 23.7%, 3 main canals were observed: 1 mesiofacial, 1 mesiolingual and 1 distal. In the remaining 3.9%, 1 non-independent supernumerary canal was seen in a distolingual position.

Application of Stewart-Hamilton's formula to the activity-time curve recorded over a left ventricular region of interest following an intravenous bolus injection of a radioactive indicator in gamma camera hepatography has resulted in a new method for determination of the clearance rate constant of the indicator (i.e. the ratio of the clearance to the plasma volume). In a group of 19 normal subjects the clearance rate constant was 0.116 +/- 0.036 min-1 (means +/- 1 S.D.) with 99mTc-diethyl-IDA (SOLCO HIDA) and 0.184 +/- 0.037 min-1 (means +/- 1 S.D.) with 99mTc-diethyl-iodo-IDA (SOLCO IODIDA) in 15 normal subjects. The clearance rate constant is assumed to represent mainly hepatic clearance of the radioactive indicator and to a much smaller extent renal clearance. The literature shows diverging results as to the clearance of 99mTc-diethyl-IDA and the reasons for this are discussed. The correlations between the clearance rate constant of 99mTc-diethyl-IDA and a number of laboratory variables with relation to liver function were moderate to non-existent in a group of 16 subjects with abnormal values of at least one of these variables. The rate constant for clearance as described in the paper represents a non-invasive method for rapid evaluation of the uptake capacity of the liver and, in particular, with regard to the polygonal cells of the liver parenchyma when IDA derivatives are employed. The clinical usefulness of the clearance rate constant is probably superior to the group of routine laboratory variables which also describe other functions than liver uptake.