Scanning electron microscopy of cavity margins finished with ultra-speed instruments.

The quality of the margins of the box portions of Class II cavities finished with rotating instruments at ultraspeed was assessed. In a closed row of teeth, an adequate finish was obtained at the embrasure margin where the burs rotated toward the tooth surface and into the cavity. The finish of the opposite embrasure margin and of the gingival margin was imperfect, regardless of the instrument used.

Resistance to fracture of endodontically treated premolars restored with glass ionomer cement or acid etch composite resin.

MOD cavity preparations in 64 endodontically treated premolars were restored using four different methods. Copper rings were filled with commercial hard-setting cement and the teeth were placed into the cement up to the level of the cementoenamel junction. The teeth were grouped according to restorative method, mounted in an Instrom T.T. machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. The resistance to fracture of the teeth was the same when they were restored with glass ionomer cement as a base over which an amalgam or composite resin was placed or with acid-etched resin. When the entire cavities were filled with glass ionomer cement the resistance to fracture of the teeth decreased significantly compared with the acid etch resin technique.

The use of transparent teeth in the teaching of preclinical endodontics.

Demineralized teeth, which were cleared and hardened in xylene, were used in the teaching of preclinical endodontics. The teeth appeared well suited for the purpose. Of 39 students attending the course, 30 students thought that the use of transparent teeth had facilitated the learning of endodontic techniques.

Darkfield microscopic spirochete count in the differentiation of endodontic and periodontal abscesses.

A previous experimental study indicated that a darkfield microscopic spirochete count of 0 to 10% was indicative of a lesion entirely of endodontic origin and a count between 30 and 58% suggested a purely periodontal lesion. Two clinical cases are described where the differentiation of an endodontic lesion from a periodontal lesion was difficult and the traditional diagnostic indicators either could not be used or gave conflicting results. In these cases the percentage of spirochetes in the exudates of the lesions was used as an aid to diagnosis with successful treatment results.

The use of dental services among Norwegian adults in 1973.

The dental treatment pattern and its determinants were surveyed in 1973 by interviews with a sample comprising 1,632 persons drawn to cover the total Norwegian population aged 15 and above. In all, 58% of the interviewees stated having visited a dentist during the year prior to the interview. In contrast, 16% had not consulted a dentist for at least 5 years. Fifty-five percent of the sample reported having received fillings at the last dental visit and 15% reported having received some periodontal and/or preventive treatment. Regular (at least annual) treatment attendance was claimed by 52% of the sample. However, some respondents had seemingly embellished their treatment behavior, and a relatively valid estimate for the current proportion of regular treatment attenders was considered to be 40% of the adult population in Norway. Sex and geographic region were found to be the most influential predictors of the recent treatment pattern, whereas school dental treatment had a major influence in youth. Dental conditions including the wearing of dentures was the reason most often given for not seeing a dentist on a regular basis.