Jakob Valderhaug

Assessment of the periapical and clinical status of crowned teeth over 25 years

OBJECTIVES The purpose of this study was to examine radiographically changes in the periapical status and compare the clinical status of teeth with a vital pulp and root-filled teeth restored with crowns and bridge retainers during 25 years. METHODS During 1967/68, 114 patients received prosthodontic treatment by senior dental students at the Oslo Dental Faculty. In all, 291 teeth with a vital pulp and 106 root-filled teeth were restored with 158 prostheses. All root-filled teeth were restored with a cast dowel and core. The casts were made in a type-3 gold alloy, and cemented with zinc phosphate cement. Forty-six teeth were restored with crowns and 351 teeth with bridge retainers. Radiographs were taken preoperatively, immediately after cementation, and every fifth year. Two independent observers assessed the periapical status on the radiographs according to the PAI-index. At the 25 years examination, 32 patients (28%) with 101 restored teeth (24%) remained in the study. Survival rates of the prostheses and of the restored teeth were estimated using Kaplan-Meyer non-parametric statistics. RESULTS The PAI-score of the periapical status deteriorated in 13 vital and four root-filled teeth. The survival rates of the fixed prostheses were not influenced by the pulp vitality of the restored tooth at the baseline. The survival rates of the restored teeth with a vital pulp and of the root-filled teeth were similar. Clinical failures were recorded on approximately one-third of the restored teeth. The main reason for tooth failure was caries (12%), and for the teeth with a vital pulp also pulpal deterioration (10%). Estimates of the proportions of crowned teeth with a vital pulp that will remain free from signs and symptoms of pulpal deterioration were 98% after five years, 92% after 10 years, 87% after 20 years and 83% after 25 years. CONCLUSIONS The incidence of periapical lesions on radiographs of crowned teeth was low during 25 years observation. Crowned, root-filled teeth with a high quality endodontic treatment and an optimal morphology of the dowel and core have a similar survival rate as crowned teeth with a vital pulp. A high proportion of crowned teeth with a vital pulp will remain free from signs and symptoms of pulpal deterioration over 25 years.

Assessment of an additive index for plaque accumulation on complete maxillary dentures

There appears to be a relation between accumulation of plaque on complete maxillary dentures and denture stomatitis. The present index was introduced to assess the location and amount of plaque in some areas of the fitting surfaces of complete maxillary dentures. Scores were recorded in five defined areas on the denture base. Four ranked scores were used: 0 - no visible plaque, 1-plaque visible only by scraping on the denture base with a blunt instrument, 2-moderate accumulation of visible plaque, and 3-abundance of plaque. By summing up the scores from the five areas, the plaque was recorded on a scale from 0 to 15 points. The inter- and intra-reliability were tested for two examiners using the index on 50 complete maxillary dentures. Expressed in terms of Scotts Pi, inter-examiners agreement was 0.83, and intra-examiner 0.83 and 0.82 for examiners A and B, respectively. A simplification of the index was also presented. In this index the scores 0 and 1 were combined to score 0, -no visible plaque, and score 2 and 3 were combined to score 1, -visible plaque. Using this index, Scotts Pi was calculated to 0.91 for inter-examiner reliability. For the intra-examiners reliability Scotts Pi was calculated to 0.91 for examiner A and 0.89 for examiner B.

Dimensional stability of elastomeric impression materials in custom-made and stock trays

Elastomeric impression materials for fixed prosthodontics are considered most stable when they have an even thickness of 2 to 4 mm. To obtain this, a custom-made impression tray is recommended. The purpose of the present study was to compare the stability of impressions made in custom trays and trays made of chromium-plated brass. The impression materials chosen were polyether and silicone. Two master models of the upper jaw were made of metal. The canines and first molars represented abutment teeth with flat occlusal surfaces. An engraved cross on each surface made it possible to measure in a microscope the distances between the abutment teeth on the models and in the impressions. The accuracy of the method was within +/- 8 micron. Twelve standardized impressions were made with each impression material in the two types of trays. The distances between the abutment teeth were measured immediately on removal of the impression, and after 1 and 24 hours. Although ample amount of impression material (2 to 9 mm) was allowed, the linear dimensional stability of the impressions made in stock trays was not inferior to the stability of impressions made in custom-made trays.

The prevalence of malocclusion in 13- to 15-year-old children in Nairobi, Kenya

Data on occlusal features and the need for orthodontic treatment in Kenya is scanty. This study was carried out to determine the prevalence of malocclusion in children in Nairobi, Kenya. Nine hundred and nineteen children aged 13-15 years (468 male, 451 female) were examined. The registration method used was that described by Björk et al. The prevalence of malocclusion was 72%. The predominant anteroposterior relationship of the dental arches was neutral occlusion (93%). Specific malocclusion traits were highest for crowding (19%), rotations (19%), posterior crossbite (10%), maxillary overjet (10%), and frontal open bite (8%). There was no statistically significant difference in the overall prevalence of malocclusion between males and females, but some occlusal traits were significantly higher in males. Although the findings indicate that the present population is not characterized by a substantial difference in the overall prevalence of malocclusion compared with other communities, some traits differed in prevalence from those reported elsewhere.

A histologic study of experimentally induced periapical inflammation in primary teeth in monkeys

Abstract Periapical inflammation was induced in monkey primary teeth by removing the pulp tissue and leaving the root canals open to the oral cavity for up to 360 days. Fifty-two experimental teeth and a similar number of contralateral control teeth from six monkeys were used. Periapical inflammation developed in 45 teeth, Eighteen of the teeth had abscesses, granulomas and cysts without communication to the oral cavity. Thirty-one fistulae developed from the periapical area of 27 teeth. Pathologic changes in the interradicular areas were seen only in relation to periapical inflammation. Root resorption had, however, taken place in all teeth adjacent to the inflammatory process. When the dentinal tubules ended in a vital periodontal membrane, bacteria were found only in the inner third of the dentinal tubules. In cases where the tubules ended in necrotic periodontal tissues, bacteria could be observed along the entire length of the dentinal tubules. Incorporation of 3 H-thymidine in epithelial cells of the periodontal membrane in connection with periapical inflammation was observed regularly. On the basis of the study, a restrictive attitude towards endodontic treatment of primary teeth with a necrotic pulp is suggested.

A histologic study of experimentally induced radicular cysts

Abstract Periapical cysts were induced in monkeys by leaving the root canals open to the oral environment for periods up to 360 d. Thirty-nine permanent teeth from four monkeys were included in the experiment. Thirteen of the teeth had some vital pulp tissue left in the root canals when the animals were sacrificed. Granulomas and cysts did not develop in these teeth. Granulomas with proliferating epithelium were present in several of the teeth with observation periods from 100 to 199 d. Periapical cysts developed in 11 out of 16 teeth with an observation period of more than 200 d. In small, developing cysts several epithelial patterns were seen with arcades and rings of proliferating epithelium surrounding granulation and necrotic tissue. The large, matured cysts had a circular to ovoid form with a continuous lining of epithelium. Toward the lumen a zone of degenerated cells was observed. Outside the epithelial cells there was a broad zone of loose connective tissue infiltrated with exudate cells. Some distance from the root surface the epithelial lining was thin; closer to the root surface the epithelial lining became thicker, with strands of epithelial cells penetrating into the connective tissue. There was always a close connection between the root surface and the epithelium of the cyst wall.

Periapical inflammation in primary teeth and its effect on the permanent successors

Abstract Periapical inflammation was induced in monkey primary teeth by removing the pulp tissue and leaving the root canals open for varying periods from 20 to 360 days. Fifty-two experimental teeth and a similar number of contralateral control teeth from six monkeys were used. In 16 out of 45 teeth with periapical inflammation the permanent tooth germs had been affected. The dental epithelium had undergone metaplasia to cuboidal or squamous epithelium in areas affected by the inflammation. 3 H-thymidine-labeled cells in the dental epithelium were seen regularly in the area located close to the inflammatory processes. Pathologic changes in the hard tissue formation had taken place in seven, of the permanent tooth germs. Increased root resorption was seen in all primary teeth adjacent to the inflammatory processes. No difference, however, was observed in the eruption pattern between the experimental and the control teeth.

Fluorosis of deciduous teeth and first permanent molars in a rural Kenyan community

The severity and distribution of fluorosis in the deciduous dentition of 76 children in a low-income community near Nairobi were studied. Seventeen children comprised a low-F (fluoride) group (water less than 0.7 ppm F) and 59 a high-F group (water approximately 9 ppm F). The high-F group had scores greater than or equal to 5 in the Thylstrup & Fejerskov classification system for 29% of the deciduous tooth surfaces, compared with 7% in the low-F group. Comparison between the scores of the second deciduous and the first permanent molars showed no significant difference in the high-F group (p greater than 0.001), whereas the deciduous molar was significantly less severely affected in the low-F group (p less than 0.001). The deciduous molars of the two groups differed significantly (p less than 0.002), but not the permanent molars (p greater than 0.10). Early introduction of tea might have been a major contributor to the distributions of fluorosis, particularly in the low-F group.

Oral hygiene practices and periodontal health in primary school children in Nairobi, Kenya.

The purpose of this study was to obtain data on the oral hygiene practices, oral hygiene status, and periodontal health among primary school children in Nairobi. The study group consisted of 513 children, 262 aged 6-8 years and 251 aged 13-15 years. The children were from 6 schools randomly selected among the 154 public primary schools in the city. The clinical examination was performed in a room with natural daylight, using the WHO (1980) criteria. Although most of the children reported brushing habits, 75% of the index tooth surfaces in the younger and 55% in the older age group had visible plaque. In both age groups about 25% of the index sites had gingivitis. Moderate amounts of calculus were recorded among the older children. Only two children had periodontal pockets greater than or equal to 4 mm. There was no statistically significant difference (p greater than 0.05) between males and females recorded with plaque and gingivitis in the younger age group. In the older group, however, a significantly higher proportion of males (p less than 0.05) were recorded with plaque and gingivitis. The oral hygiene practices and oral hygiene status were poorer among children from low than from high socioeconomic status. Provision of dental health education for children in Nairobi is recommended.

A histologic study of experimentally produced intra-oral odontogenic fistulae in monkeys.

Abstract Intra-oral dental fistulae from periapical inflammation were produced in monkeys by removing the pulp tissue and leaving root canals open for periods varying up to 360 d. Thirty-nine permanent teeth from four monkeys were included in this experiment and intra-oral fistulae developed in thirteen of them. In 11, the orifices were on the vestibular side and in two they were on the lingual side. Epithelium was not observed in three of the fistulous tracts, six tracts were partly lined with epithelium, and four had a complete epithelial lining. In cases with exacerbation, the tracts were not lined with epithelium. Connective tissue fibers and cells always separated the alveolar bone from the inflammatory areas.