During orthodontic treatment of 29 patients with a Class II malocclusion, the remaining overjet was corrected surgically by intraoral mandibular distraction osteogenesis. The patients were divided in two groups. Group A was treated orthodontically in a two-phase approach, using functional and fixed appliances. Group B was treated in a one-phase approach with only fixed appliances. Before treatment the differences in age, gender and severity of the malocclusion between the groups, were not statistically significant. After distraction-osteogenesis, all orthodontic treatments could be finished successfully. The mean treatment time was for group A 44.2 and for group B 28.6 months. The difference was statistically significant (p < 0,001). The mean orthodontic treatment time after distraction osteogenesis was 9.1 months. The mean cost for the orthodontic treatment was not statistically significant different between the groups.

There are different methods to produce digital head films and all have advantages and disadvantages. With a digital head film and a computer programme for digital cephalometry an analysis can be performed easily. All existing computer programmes for digital cephalometry use reference values to compare with the patient’s values. However, the magnification factors of the two data sets, which are compared, must be known and correction to the same magnification must be possible within the programme. Furthermore, the reference values should be age, gender, and population related. Many commercially available programmes do not fulfil these criteria. A welldesigned programme for digital cephalometry should have the possibility to calculate age and gender-related reference values based on values of the target population. Furthermore it should have the possibility to analyse several longitudinal head films at the same time and to present the data graphically. A national survey among Dutch orthodontists by the end of 2000 demonstrated that 35% of Dutch orthodontists used digital cephalometry in their office. The most commonly used analysis was the Steiner-Tweed analysis, which was performed by nearly 60% of the orthodontists.

The removal of gutta-percha and sealer from endodontically treated root canals may prompt the use of organic solvents. In the present article a number of possible solvents are described and, based upon the literature, their efficacy is assessed. Some solvents, amongst which chloroform, xylene and halothane are almost equally efficient, although all leave a debris of gutta-percha and sealer in the root canals behind. Only chloroform solves AH26 and most probably AH-plus, but very slowly. Eucalyptol and turpentine oil are slow dissolvers. Orange oil and limonene are promising. The data on other solvents, if candidates at all, are scarce. The choice of a solvent is co-determined by factors such as toxicity and sensitisation, which will be described in a second publication.

For patients with complaints of either hyposalivation or hypersalivation, or saliva with altered properties, the secretory flow rate can be determined in an easy way to study whether abnormalities are detectable. It is most simple to measure the flow rate of whole saliva. After collection of saliva the oral fluid can be analyzed on rheological properties, such as viscosity and elasticity and also on pH and its chemical composition. Oral fluid is the combined fluid in the oral cavity mainly composed of glandular salivas, and in addition crevicular fluid and serum exsudate. For collection of oral fluid it is of crucial importance to standardize the conditions. The diverse collection methods and their application for patient research with oral complaints are described.

A guest editorial of the International Journal of Prosthodontics was written about ‘distance learning’. The author described a postgraduate course for a degree of Master of Clinical Dentistry, fully digitally organised and using internet for the communications between professionals and teachers. It has the advantage that the professional does not have to travel and can continue his practice, and that the clinical work can be undertaken in his own practice. In the Netherlands, only internal courses are given, but courses based on distance learning can be taken into consideration.

In this article, a patient is presented who was treated by a maxillo-mandibular advancement osteotomy, in order to increase the volume of the oropharynx as a final treatment of the obstructive sleep apnea syndrome. This syndrome is a common affliction, characterized by excessive daytime sleepiness and unintentionally falling asleep. It can be diagnosed by patient history and polysomnography. Nasal-continuous positive airway pressure is the golden standard of treatment. However, in mild to moderate cases of the syndrome, treatment with a mandibular reposition appliance is also an option. The extraoral device of the first treatment option as well as the intraoral appliance of the second treatment option are demanding patients’ compliance. Therefore, research into other treatments is necessary. The initial results of the advancement osteotomy among six patients were very good and in accordance with other literature reports. These results justify further research to clarify the importance of this treatment option of the obstructive sleep apnea syndrome.

The Dutch Society for Dentists is a scientific organization on behalf of and for the benefit of Dutch dentists. The society promotes dental research and it’s appliance in daily practice. In this article a short review of the organization and it’s website is presented.