Tooth-supported telescopic prostheses in compromised dentitions: a clinical report.

This article describes indications for treatment with telescopic restorations on patients with periodontally and endodontically compromised dentitions that require splinting, with special emphasis on treatment that restores the entire dental arch. Stabilization of compromised teeth with fixed splinted restorations is usually inadvisable because of the risk factors involved, such as eventual localized abutment failure. Detachable telescopic prostheses may be preferred as a near equivalent or substitute because they can be detached and repaired without reconstruction of the entire restoration. Retentive and splinting properties of detachable telescopic restorations can be as effective as FPDs. Inner telescopic copings can be cemented as individual crowns to facilitate the procedure. Telescopic restorations can be retrieved by the patient for cleaning and easy access to the entire marginal periodontal circumference of the abutments. This promotes effective home care and oral hygiene. In addition, principles of design and indications, as well as technical and clinical factors, were discussed.

The closure of the gingival crevice following gingival retraction for impression making.

Scant attention has been paid to the effectiveness of chemomechanical displacement of the gingiva prior to impression making for fixed partial dentures. The closure of the gingival crevice following removal of medicated retraction cord was observed using a miniature video camera. Sulcular widths were measured at time intervals at the midbuccal and transitional line angle areas. The closure rate of the transitional line angle area was significantly faster than that of the mid-buccal area during the first 90 s. An average sulcular width of 0.2 mm was reached at the transitional line angle after less than 30 s.

The effect of displacement time on gingival crevice width.

The authors investigated the length of time medicated displacement cord should remain in the gingival crevice prior to impression making. A silk cord (Deknatel) was placed into the sulcus and was not removed during the study. Medicated cords (Hemodent on Ultrapak #1) were placed into the gingival sulcus for 2, 4, 6, and 8 minutes. Following cord removal, closure of the sulcus was recorded at intervals using a miniature video camera. Crevicular widths were measured at the midbuccal and transitional line angle areas. At both the midbuccal and transitional line angle areas, gingival crevices displaced for 2 minutes were significantly smaller at 20 seconds (P < .05) than crevices following displacement for 4, 6, and 8 minutes. No significant difference in crevicular width was found at any time period after cord removal for crevices displaced for 4, 6, and 8 minutes. At the transitional line angle, crevicular widths were significantly smaller than at the midbuccal at 20 seconds for all times and remained so up to 180 seconds. To achieve a crevicular width of 0.2 mm, cord should remain in the gingival crevice for an optimum time of 4 minutes prior to impression making when using the materials evaluated in this study.

Modalities of treatment for the combination syndrome.

A series of destructive changes occurring in the jaws of patients wearing a complete maxillary denture opposed by a mandibular distal extension removable partial denture have been described as the combination syndrome. However, the syndrome does not occur in all patients. Those patients who have not developed signs of the combination syndrome and whose mandibular anterior teeth are well preserved and not overerupted may be treated conservatively with a mandibular removable partial denture. A properly designed removable partial denture that distributes occlusal stresses over hard and soft tissues minimizes the risk of developing the combination syndrome. Nevertheless, the overdenture seems to provide a more predictable prognosis, especially for patients who already have the combination syndrome or whose mandibular anterior teeth are structurally or periodontally compromised or overerupted. The treatment modality is determined by the apparent potential of the patient to develop the combination syndrome and by the condition of the remaining mandibular anterior teeth.

Root-retained overdentures: Part II--Managing trauma between edentulous ridges and opposing dentition.

Overdentures designed to prevent direct occlusal trauma to the residual ridge may either forestall or reduce residual ridge resorption. Overdentures may also be used to improve abnormal maxillomandibular relations, thereby enhancing both function and esthetics.

Root-retained overdentures: Part I--Biomechanical and clinical aspects.

Despite recent developments in dental implantology, the conservative approach to root preservation is still valid. In view of increased root caries rate in the elderly and lax oral hygiene habits of most overdenture wearers, placing protective copings on root abutments, when economically feasible, is the preferred method of treatment. Retention of overdentures is increased by including stud attachments in the abutments. Incorporation of cast metal frameworks is recommended to prevent base fractures.

Occlusal considerations for partially or completely edentulous skeletal Class II patients. Part II: Treatment concepts.

Four basic concepts must be considered when developing the prosthetic occlusion for skeletal class II patients: (1) Centric relation must be used as a reference position to relate the mandible to the maxillae; (2) the posterior denture teeth must be positioned close to their former positions; (3) freedom of movement must be created in eccentric movements; and (4) multiple occlusal contacts must be provided in centric and eccentric positions. We have described a method that incorporates these basic concepts and provides a harmonious occlusal arrangement for both edentulous and partially edentulous class II patients.

Occlusal considerations for partially or completely edentulous skeletal class II patients. Part I: Background information.

Although approximately 15% of the population may be classified as having the skeletal class II relationship, this group of patients is far from homogeneous. Two prototypes were used to delineate various problems in the prosthodontic occlusion that dentists may encounter with these patients. A satisfactory occlusion is difficult to achieve because of skeletal discrepancies, limited space for occlusal contact, steep guidance factors, and the necessity for multiple eccentric occlusal contacts because of the significant range of mandibular motion.

Scanning electron microscopy studies on the origin and structure of matrix vesicles in epiphyseal cartilage from young rats.

Epiphyseal plates of young rats were examined by scanning electron microscopy to study the distribution, morphology and origin or the matrix vesicles (calcifying globules) and the results were compared with the findings on transmission electron microscopy. The matrix vesicles, 0.1 micrometer in diameter, were found to cover the intercolumnar septa and to increase gradually in number from the zone of proliferation to the zone of provisional calcification. In the intercolumnar septa of hypertrophic and calcifying cartilage, the vesicles aggregated to form calcospherites, i.e. mineralized globules about 1 micrometer in diameter. Chondrocytes showed numerous cell processes that were longer and more abundant in the more mature cells. In the zone of maturation many processes had enlarged tips with small globular projections ("bulges"), about 0.1 micrometer in diameter, which resembled the matrix vesicles covering chondrocytic lacunae. In the zones of hypertrophy and provisional calcification, many of these bulges aggregated to form larger, spherical structures. It is suggested that matrix vesicles in cartilage originate by budding from cell processess, and that in the zone of provisional calcification they aggregate to form the calcospherites, which are the loci of initial calcification of cartilage.