284 Reviews and abstracts Am. J. Orthod. Dentofac. Orthop. March 1991

prosthodontics. Too often I found myself failing to un- derstand the author's arguments for advocated proce- dures, and too often I questioned his reliance on the cited literature; again the references appeared inac- curate.

Because neuromuscular anatomy has become one of the scientific foundations of clinical dentistry, it seems reasonable to predict that neuromuscular phys- iology eventually can serve the same purpose, but not on the basis of this book:Finally, I shall omit a detailed critique of the/presented diagnostic and therapeutic in- strumentation but will only remind the potential reader that the particular electronic devices have in many in- stances failed to pass simple performance tests; that is, they have failed to yield proper output signals in re- sponse to standardized input signals.

L. V. Christensen

Glass Ionomer and Resin-Based Fissure Sealants: A Clinical Study Ingegerd Mej~re and Ivar A. Mjbr Scand. J. Dent. Res. 1990;98:345-50

The aim of this study was to compare the retention rate of a glass ionomer cement formulated for fissure sealing with two resin-based sealants. Two hundred eight occlusal fissures of permanent molars and pre- molars were sealed with either Fuji III, Delton, or Con- cise WS sealant by four dentists. Clinical assessments and a replica scoring technique were used to register the performance of the sealants at baseline, after 6 to 12 months, and then yearly up to 5 years. As judged clinically, 647 % of the glass ionomer sealants were lost within 6 to 12 months and 84% after 30 to 36 months. Although total loss was recorded clinically for the ma- jority of the glass ionomer sealants, some retained seal- ant was observed in the tooth replicas in 93% of them. The clinical evaluation of the resin-based sealants showed an average complete retention rate of 90% after 41/2 to 5 years. The corresponding figure with the replica technique was 58%. Caries was recorded in 5% of the resin-based and in none of the glass ionomer-sealed surfaces.

The authors caution that any conclusion about a possible long-term caries-preventive effect cannot be drawn from the present results, but it is possible that the retention of small amounts of glass ionomer sealant may be sufficient to prevent caries in the entire pit and fissure system of a tooth.

Alex Jacobson

A Study of Computerized Measuring System of Occlusal Area and Occlusal Pressure Distribution Akihiko Nakasima, Motoshi Ichinose, Yasuhide Takahama, and Masaki Nagata J. Jpn. Orthod. Soc. 1990;49(1):37-46

A new computerized device to visualize pressure distribution on the occluded dentition was developed. The device enables the dentist to evaluate "occlusion" quantitatively from the structural and functional stand- points. The sensor bite plate consists of pressure- conductive rubber (PCR) sandwiched between two sub- strates printed with thin conductive stripes. The stripes form an X-Y grid of a maximum of 4096 sensing points as electrodes. Each amount of resistance on the point where bite force is added is transformed into a pressure value memorized by the microcomputer. A software system displays the pressure level with four different colors on the CRT screen as a scattergram. The infor- mation can be printed and saved.

As a method of functional examination, the mea- surement errors fell in a permissible range. The authors believe it to be an effective way of diagnosing, treating, and analyzing occlusion.

Alex Jacobson

Unilateral, Isometric Bite Force in 8 to 68-Year-Old Women and Men Related to Occlusal Factors Merete Bakke, Betty Holm, Birgit Leth Jensen, Lars Michler, and Eigild M611er Scand. J. Dent. Res. 1990;98:149-58

Unilateral bite force was studied in 63 women and 59 men, 8 to 68 years of age. The subjects had a min- imum of 24 teeth and no symptoms or signs of disorders of the craniomandibular system. Bite force was stronger in men (n522) than in women (n441). It increased with age until 25 years (p < 0.00<31). The level decreased significantly after this age in women, whereas it only tended to decrease in men and not until after the age of 45 years. Body height was positively associated with force. However, the strongest correlation (r 0.43-0.49, p < 0.01) with adult bite force was occlusal contact. The normal bite-force values with important determin- ing factors provide reference data for screening of el- evator muscle strength in routine examination of cra- niomandibular function.

Alex Jacobson