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The traditional method of evaluating student tooth preparations in preclinical courses has relied on the judgment of experienced clinicians primarily utilizing visual inspection. At times, certain aids such as reduction matrices or reduction instruments of known dimension are used to assist the evaluator in determining the grade. Despite the skill and experience of the evaluator, there is still a signiicant element of uncertainty and inconsistency in these methods. Students may perceive this inconsistency as a form of subjective, arbitrary, and empirical evaluation, which often results in students' focusing more on the grade than the actual learning or developing skills necessary to accomplish the preparation properly. Perceptions of favoritism, discrimination, and unfairness (whether verbalized or not) may interfere with the learning process. This study reports the use of a new experimental scanning and evaluation software program (E4D Compare) that can consistently and reliably scan a student's tooth preparation and compare it to a known (faculty-determined) standardized preparation. An actual numerical evaluation is generated by the E4D Compare software, thereby making subjective judgments by the faculty unnecessary. In this study, the computer-generated result was found to be more precise than the hand-graded method.

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Summary The paper describes pathological findings in 45 cases of atrial fibrillation and discusses the possible nature of this arrhythmia in the horse. Résumé Cet article décrit les constatations pathologiques faites dans 45 cas de fibrillation auriculaire chez le Cheval et discute de la nature possible de cette arythmie. Zusammenfassung Die Arbeit beschreibt pathologische Befunde bei 45 Fällen von Vorhof‐Flattern und diskutiert das Wesen dieser Arrhythmie beim Pferd. Sumario El Trabajo describe los hallazcos clinicos en 45 casos de fibrilacion atrial y se discute la posible naturaleza de esta arritmia en el caballo.

SUMMARY The paper describes the gross heart findings in 1,557 horses. Approximately 25 per cent had cardiac lesions, of which most were valvular. There was a marked predominance of left heart involvement and the aortic valve was the valve most frequently affected. Suggested explanations for these findings are briefly discussed. RÉSUMÉ L'article décrit les observations cardiaques macroscopiques faites chez 1557 chevaux. Pour 25 pour cent environ, ces coeurs montrèrent des lésions dont la plupart affectaient les valvules. Le coeur gauche parut être le plus souvent concerné et la valvule aortique parut être le plus fréquemment atteinte. On donne des explications à ces constatations. ZUSAMMENFASSUNG Die bei 1557 Pferden makroskopisch nachgewiesenen Herzveränderungen werden beschrieben. In ungefähr 25 % der Fälle konnten Läsionen gefunden werden, die zum grössten Teil die Klappen betrafen. Das linke Herz erwies sich als viel häufiger erkrankt als das rechte und unter den Klappen war die Aortenklappe häufiger verändert als die anderen. Mögliche Erklärungen für diese Resultate werden kurz besprochen. SUMARIO El papel describe el total de resultades encontrados en 1557 caballos. Aproxomadamente el 25 % tenía lesiones cardiacas de la cuales la mayoría era valvular. Había gran predominancia sobre el corazón izquierdo, la válvula aórtica era la válvula más frecuentemente afectada. Se citan explicaciones sobre estos descubrimientos, son brevemente expuestos.

Summary The paper describes five cases of atrial fibrillation detected after racing. In four of them, the arrhythmia disappeared spontaneously within 24 h and they were regarded as paroxysmal in type. In the fifth case, which won its race, the arrhythmia persisted for at least 45 h after racing. It was therefore regarded as an example of persistent atrial fibrillation. It was then treated with quinidine sulphate which restored sinus rhythm. It would seem that paroxysmal atrial fibrillation may be a cause of sudden decrease in racing performance.

Summary Following the derivation of resultant cardiac dipole moments from the integration of body surface potentials throughout the cardiac cycle in three horses previously reported, this paper describes observations on the same animals to determine the siting of bipolar leads in the three body axes to produce vectorcardiograms similar to those from the dipole moment studies. The results were compared with those using Einthoven's system. The experimental leads gave more accurate portrayal of the cardiac electric field than the conventional Einthoven's triangle which particularly in the horizontal plane was not representative of the cardiac electric forces. Résumé Cet article décrit l'emplacement des dérivations bipolaires suivant trois axes qui permettent d'obtenir des vectocardiogrammes comparables à ceux obtenus précédemment (étude de la résultante des moments du dipole cardiaque lors de la révolution cardiaque à partir du champ électrique superficiel). Les résultats sont comparés à ceux obtenus par la méthode d'Einthoven. Les dérivations expérimentales donnent une image plus précise du champ électrique du coeur que ne le font celles dessinant le triangle d'Einthoven. Ce dernier, notamment dans le plan horizontal, n'est point chez le Cheval représentatif des forces électriques du coeur. Zusammenfassung In einem früheren Bericht wurde die Bestimmung kardialer Dipolmomente beschrieben, die auf Grund der Integration von Körperoberflächen‐Potentialen während des ganzen kardialen Zyklus bei 3 Pferden gewonnen werden konnten; der vorliegende Artikel beschreibt nun die Beobachtungen an den gleichen Pferden, die gemacht worden sind, um die Placierung bipolarer Ableitungen in den 3 Körperachsen zu bestimmen. Mit ihrer Hilfe können Vektorkardiogramme gewonnen werden, die mit denjenigen der Dipolmoment‐Untersuchungen vergleichbar sind. Die Resultate werden mit Befunden verglichen, die mit Einthoven's Ableitungen erhalten wurden. Die experimentellen Ableitungen haben eine genauere Analyse des kardialen elektrischen Feldes erlaubt als das konventionelle Einthoven'sche Dreieck, das besonders in der horizontalen Ebene nicht repräsentativ ist für die elektrischen, kardialen Kräfte.

Summary Two‐dimensional echocardiography (2DE) was performed on 22 unsedated Thoroughbred and part Thoroughbred horses weighing between 411 and 650 kg to establish normal reference values for 2DE measurements. Animals stood during examinations performed with a 3.5 MHz mechanical sector transducer using various transducer positions and tomographic planes. Right ventricular diameter (RVD), ventricular septal thickness (VSTh), aortic diameter (AoD), area of the chordal lumen of the left ventricle (CTA), left ventricular diameter (LVD) and left atrial diameter (LAD) were determined at ventricular end‐diastole (Ed) and/or end‐systole (Es). Fractional shortening (FS) of the left ventricle and end‐systolic left atrial to aortic ratio (LADEs: AoD‐Es) also were calculated. Echocardiographic data were related to body weight by linear regression analysis. Intra‐observer variability was checked in five horses by measuring each parameter during each of 10 consecutive cardiac cycles. The 2DE data were compared with M‐mode values in published reports. In the 18 horses whose weight did not exceed 551 kg, repeatable recordings of good quality were obtained, and 2DE measurements could be made using intra‐cardiac reference points. Increasing body weight proved to impose substantial limitations on measurements taken with the available machine and transducer. This problem might be overcome by using probes of lower frequency or equipment with higher quality image display at greater depth. The following parameters correlated significantly to body weight: VSTh‐Es (r = 0.69; P<0.01). AoD‐Es (r = 0.64; P<0.01) and CTA‐Es (r = 0.84; P<0.001). However, technical limitations prevented determination of the relationship between bodyweight and CTA‐Ed and LVD‐Ed. For each parameter, good reproducibility of values was found because the mean coefficient of variation (CV) varied between 2.6 and 7.2. In this study, 2DE provided reliable qualitative and quantitative assessment of cardiac anatomy and function, but its limitations also must be considered and it should be used in conjunction with other clinical procedures.