The objective of this investigation was to examine the dentofacial features of a group of patients with hypodontia, in particular assessing whether cephalometric analysis confirmed the clinical assumption of a reduced lower face height, and to determine the relationship of these facial features with different numbers of missing teeth. It took the form of a cephalometric study, undertaken in a dedicated Dental Hospital clinic for patients with hypodontia. The study group comprised 59 patients seen on the Hypodontia Clinic: 32 females, 27 males, mean age 13.1+/-3.1 years (range 6-23 years). The average number of missing teeth was 7 (SD 5), ranging from 1 to 21. The mean SNA, SNB, and MMA angles were within normal limits, but there was a statistically significant reduction in the MMA when more than one tooth type was missing (P = 0.007) and the ANB angle decreased as the number of missing tooth types increased (P = 0.034). The mean values for the whole sample were within the normal range and did not demonstrate any feature specific to the group, but patients with more severe hypodontia showed tendencies to a Class III skeletal relationship and a reduced maxillary-mandibular planes angle.

Computer-assisted learning (CAL) is a relatively new method of teaching. Few evaluations have been made which compare the new CAL methods with conventional teaching. This study used a text-based CAL package designed to teach orthodontic assessment and basic principles of treatment planning. It assessed the knowledge gain of 49 dental undergraduate students when taught orthodontic assessment and treatment planning by either CAL or conventional tutorial. Both groups made significant gains in knowledge. However, students who were taught by the conventional tutorial made a significantly greater gain than those taught by CAL.

A significant number of patients exhibit white spots of enamel decalcification after orthodontic treatment, despite the use of preventive regimes. The hydrochloric acid-pumice micro-abrasion technique offers a method for improving the appearance of these lesions where they are cosmetically unacceptable. The clinical procedure is described and the effects of the technique upon the dental structures are discussed.

Summary. Three cases are described illustrating problems of root resorption related to orthodontic treatment. In the first case the short roots of many of the teeth made it inappropriate to carry out orthodontic treatment. In the second case there were no signs of root resorption initially, but, following retraction of maxillary incisors with a removable appliance, root resorption was noted affecting molar and premolar teeth, but not the maxillary incisors. In the third case several teeth had short roots, and further shortening of roots occurred during fixed appliance therapy. These cases illustrate the unpredictable nature of root resorption. Resumé. Problèmes posés par les résorptions de racine en relation avec les traitements orthodontiques: rapport de trois cas Ces trois cas illustrent les problèmes de résorption de racines en relation avec les traitements orthodontiques. Dans le premier cas, les racines courtes de plusieurs dents rendaient le traitement orthodontique inapproprié. Dans le deuxième cas, il n'y avait pas de signe de résorption des racines mais après traction des incisives maxillaires avec un appareil amovible, une résorption des racines des molaires et prémolaires est apparue mais pas de celles des incisives maxillaires. Dans le troisième cas, plusieurs dents avaient des racines courtes et par la suite une résorption des racines est apparue pendant le traitement par plaque amovible. Ces trois cas illustruent le caractère imprévisible des résorptions radiculaires. Zusammenfassung. Probleme von Wurzelresorptionen im Bezug der Planung einer orthodontische Behandlung: ein Bericht von 3 Fällen Drei Fälle von Wurzelresorptionen werden beschrieben in Zusammenhang zu einer orthodontische Behandlung. Im ersten Fall, mit kurzen Wurzein vieler Zähner, war eine orthodontische Behandlung nicht angebracht. Im zweiten Fall wurde zu Beginn kein Wurzelresorptionen festgestellt aber in der Folge der Retraktion der Frontzähne, mit einer abnehmbren Apparatur, wurden Resorptionen an der Molaren und Prämolaren gefunden aber nicht an den Frontzähne. Im dritten Fall hatten einige Zähne kurze Wurzein und während der Behandlung mit einer fixen Apparatur erfolgten weitere Kürzungen. Resumen. Problemas de reabsorción radicular relacionados con el plan de tratamiento ortodóntico: reporte de tres casos Se describen tres casos ilustrando reabsorción radicular relacionadas con tratamiento ortodóntico. En el primer caso, las raíces cortas de muchos de los dientes hizo que el tratamiento ortodóntico no fuera posible. En el segundo caso no hubo signos de reabsorción radicular inicialmente, pero despues de la retracción de los incisivos maxilares con aparatos removibles, se notó reabsorción radicular afectando los molares y premolares, pero no a los incisivos. En el tercer caso, varios dientes presentaron raíces cortas y más acortamiento radicular occurrió durante el tratamiento con aparatologia fija. Estos casos muestran la naturaleza impredecible de la reabsorción radicular.