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When a root and the overlying anatomic crown are removed as a unit, this procedure is referred to as a hemisection. Hemisection of a maxillary or mandibular molar is often a means of retaining teeth needed for restorative abutments or occlusal support. This treatment can yield predictable results using proper diagnostic, endodontic, surgical, and prosthetic techniques.

Root resective periodontal therapy is a procedure used to retain teeth needed for restorative abutments or occlusal support. Contraindications of root resective therapy include fused roots and inadequate bony support around remaining roots. When these situations exist, extraction is necessary. But in the appropriate cases, a patient with a periodontal condition resulting in alveolar bone loss in the furcation region is amenable to treatment with a predictable result using a combination of resective periodontal surgical therapy and subsequent timely prosthetic rehabilitation.

Numerous types of exercise equipment have flown on manned space flights to evaluate and maintain crew members' physical condition while on orbit. Vibrations associated with the use of some exercise equipment cause concern among microgravity scientists who are usually looking for a quiescent environment in which to run their experiments. We discuss the impact of aerobic (bicycle ergometer, treadmill) and non-aerobic (resistance devices) exercise on the microgravity environment of the Space Shuttle Orbiters and the Mir Space Station. In general, characteristic vibration disturbances due to ergometer exercise show the pedalling frequency at 2.5 to 3 Hz and the crew members' body rocking side-to-side at about half the pedalling frequency. For treadmill exercise, the footfall frequency on the treadmill platform can be clearly seen in the 1 to 2 Hz range, along with upper harmonics. The use of resistance exercise devices does not typically cause vibrations. Several vibration isolation systems used on the Orbiters and planned for the International Space Station are introduced. Finally, the responses of specific experiments to exercise vibrations are outlined.

An attractive smile has always been the focal point of a person's attention to improving esthetic appearance and thus self-esteem. It is the contrasts of shape, color, line, and texture that enable us to differentiate one tooth from another, the teeth from the gums, and the smile from the face To understand why a smile with dentition in harmony is considered beautiful, clinical examples are presented to illustrate how to apply visual perception to the dental environment. These simple principles of visualization and treatment can be successfully applied to enhance the smile of any patient.

The subgingival microflora associated with dental implants has been shown to be similar to that associated with natural teeth. Like the natural tooth, a dental implant may be susceptible to a plaque-induced gingivitis which may progress to peri-implantitis. A similarity exists between the microbial flora around failing implants and organisms classically associated with periodontal disease. The same anaerobic gram-negative organisms are found in periodontitis and peri-implantitis. The periodontium must be in a healthy state before the placement of dental implants and constantly monitored while implants are in function for early detection of potential periodontal and/or prosthodontic problems. The relationship between the microbial flora around dental implants and peri-implantitis is discussed and recommendations are presented to improve the efficacy of dental implants.

Two unique techniques that use irreversible hydrocolloid and an Omnivac matrix have been presented. The first technique is used to evaluate the adequacy and uniformity of the tooth preparation. The second technique is used to create a TIPR for the patient while the PIPR is being fabricated. The TIPR-PIPR system can be used to facilitate proper diagnosis, planning, and treatment; and it results in improved patient comfort, dentist efficiency, and increased control over the final restoration.