This longitudinal study of randomly selected Norwegian students and academicians has shown that 50% of the 17-year olds have lost no periodontal support, and the other 50% exhibited slight localized loss of attachment primarily on buccal surfaces of first molars and first bicuspids of both jaws. At 21 all students show one or more of these lesions as well as loss of attachment on interproximal surfaces. At 30 years of age the mean cumulative loss is still less than 1 mm. As they approach 40 years of age the mean individual loss of attachment is slightly above 1.5 mm or 10% of the total periodontal support, and the mean annual rate of attachment loss is 0.08 for interproximal surfaces and 0.1 mm for buccal surfaces. No case of juvenile periodontitis (periodontosis) or adult aggressive periodontitis were seen in this population. Seventy percent of the 15-year-old Sri Lankans have no or very little loss of periodontal support. However, approximately 30% exhibit localized lesions measuring between 2 and 9 mm and more than 1% have one or more root surfaces with 10 mm loss of attachment or more. In this age group the lesions occur at the interproximal and buccal aspects of lower central incisors and in first molars of both jaws. At 30 years of age the mean loss of attachment is 3.11 mm and approximately 25% of the tea laborers have lesions extending 10 mm or more below the cemento-enamel junction. As the Sri Lankan approaches 40 years of age the mean loss of attachment is 4.50 mm and the mean rate of progress of the lesion is 0.20 mm per year for buccal surfaces and 0.30 mm for interproximal surfaces. This study suggests that without interference the periodontal lesion progresses at a relatively even pace and that the progress is continuous.

Adolescent↗

PubMed1978

Dental education in the United States. Part III. The recommendations.

Explore the source record for details and available documents.

Education, Dental↗

PubMed1977

Microscopic evaluation of clinical measurements of connective tissue attachment levels.

The purpose of this study was to determine how accurately periodontal probes measure connective tissue attachment levels in beagle dogs with (1) clinically healthy gingivae, (2) experimental gingivitis, and (3) periodontitis. In the healthy and experimental gingivitis specimens the probes were inserted with a standardized force of 25 ponds. In periodontitis specimens the probes were inserted with a gentle, but nonstandardized force. After insertion, 120 plastic periodontal probes (40 in each group) were held in place by fusing them to the teeth. Blocks of periodontal tissue with the probes in situ were subsequently processed and serially sectioned. Histometric measurements were made from the sections in order to compare the level of connective tissue attachment to the level of probe penetration. In healthy specimens the probes consistently failed to reach the apical termination of the junctional epithelium (x = -0.39 mm). In the experimental gingivitis group most probes came closer to the apical termination of the junctional epithelium, but on the average still fell short by x = -0.10 mm. In periodontitis specimens the probes consistently went past the most apical cells of the junctional epithelium (x = +0.24 mm). A significant relationship between the degree of inflammation and level of probe penetration was found. No relationship was observed between histological and clinical sulcus depths. It is concluded that in beagle dogs (1) periodontal probes do not precisely measure connective tissue attachment levels, (2) inflammation has a significant influence on the degree of probe penetration, and (3) histological and clinical sulcus depths differ significantly.

Animals↗

PubMed1976

Retardation of epithelial migration in new attachment attempts in intrabony defects in monkeys.

New attachment procedures were performed in 80 three-wall intrabony defects produced adjacent to incisors and canines in monkeys. Following a reverse bevel incision, mucoperiosteal flaps were raised on the buccal and lingual aspect of 40 intrabony defects. All soft tissue was removed from the defects and following transplantation of autogenous bone grafts, the tissue flaps were replaced and sutured. On the buccal and lingual aspect of another 40 intrabony defects a split flap procedure was performed. Granulation tissue was removed from the defects and following transplantation of autogenous bone grafts, the defects were covered with free palatal grafts. The animals were sacrificed to yield observation periods from 0 to 42 days. After decalcification of the specimens and embedding in paraffin, 8-mum serial sections were cut and stained. The epithelium on the full thickness flap seemed almost unaffected by the surgical procedure and had migrated between 0.2 mm and 2.0 mm along the root surface during the first week of healing. The epithelium on the transplants degenerated almost completely within the first week after surgery and epithelial migration along the root surface was not observed until after 10-12 days. These results indicate that the migration of epithelium during the postoperative phase of new attachment attempts can be retarded by covering the defects with free palatal grafts instead of full thickness flaps.

Animals↗

PubMed1976

The occlusal fissure of unerupted third molars as an experimental caries model in man.

The aim of the present investigation was to establish an experimental model for the study of fissure caries development under conditions as similar as possible to the in vivo situation. Twenty-one blocks (2 X 2 X 3 mm) constituting part of the occlusal fissure were made from unerupted human third molars, and implanted for 60 or 90 d in mandibular molars of students. One milliliter of a 50% sucrose solution was applied to the fissures twice a day. After removal, sections were examined microradiographically in polarized light and in the electron microscope. As a control, the morphology and enamel structure of fissures from 10 unerupted third molars were studied. After 90 d a subsurface, radiolucent caries-like lesion was observed in two specimens only. When examined in air in polarized light, however, all sections exhibited caries-like lesions symmetrically located around the fissures. The 60-d material showed similar lesions, but not as frequently as the 90-d specimens. In the experimental material processed for electron microscopy revealed that the fissure plaque mainly consisted of cocci and small rods. Most often the bacteria were separated from the enamel surface by a pellicle.

Dental Caries↗

PubMed1976