Leif Tronstad

Systemic Diseases Caused by Oral Infection

Recently, it has been recognized that oral infection, especially periodontitis, may affect the course and pathogenesis of a number of systemic diseases, such as cardiovascular disease, bacterial pneumonia, diabetes mellitus, and low birth weight. The purpose of this review is to evaluate the current status of oral infections, especially periodontitis, as a causal factor for systemic diseases. Three mechanisms or pathways linking oral infections to secondary systemic effects have been proposed: (i) metastatic spread of infection from the oral cavity as a result of transient bacteremia, (ii) metastatic injury from the effects of circulating oral microbial toxins, and (iii) metastatic inflammation caused by immunological injury induced by oral microorganisms. Periodontitis as a major oral infection may affect the hosts susceptibility to systemic disease in three ways: by shared risk factors; subgingival biofilms acting as reservoirs of gram-negative bacteria; and the periodontium acting as a reservoir of inflammatory mediators. Proposed evidence and mechanisms of the above odontogenic systemic diseases are given.

Long-term Results of Endodontic Treatment Performed with a Standardized Technique

The long-term results of endodontic treatment according to Ingles standardized technique performed by undergraduate students in Oslo during 1971 were assessed. An adequate seal was found in 97% of the roots. Overfilling of the canal with excess of material greater than 1 mm was observed in 3% of the roots. The overall success rate was 91% with no statistically significant difference between the results in anterior teeth, premolars, or molars. Roots without periradicular radiolucencies showed better results than roots with radiolucencies (statistically significant). It was concluded that the standardized endodontic technique led to an improvement in the technical standard of the root fillings, and that the technique may be used regularly in all groups of teeth.

Microbiota of periapical lesions refractory to endodontic therapy.

The periapical microbiota of 36 teeth with refractory apical periodontitis was investigated. None of the teeth had responded to conventional endodontic or long-term (> 6 months), calcium-hydroxide treatment. Eight patients had received antibiotics systemically. After anaerobic culture, a total of 148 microbial strains were detected among 67 microbial species. One of the 36 lesions was culture-negative. Approximately half (51.0%) of the bacterial strains were anaerobic. Gram-positive species constituted 79.5% of the flora. Facultative organisms, such as Staphylococcus, Enterococcus, Enterobacter, Pseudomonas, Stenotrophomonas, Sphingomonas, Bacillus, or Candida species were recovered from 27 of the lesions (75%). Sulfur granules were found in 9 lesions (25%). In these granules Actinomyces israelii, A. viscosus, A. naeslundii, and A. meyeri were identified. Other bacterial species, both gram-positive and gram-negative, were detected in the granules as well. Two sulfur granules did not contain Actinomyces. Scanning electron microscopy demonstrated rod- and spirochete-like cells in the granules, and transmission electron microscopy revealed organisms with copious amounts of extracellular material. Outer membrane vesicles were also seen. Some of the granules were calcified. This study demonstrated a wide variety of microorganisms, particularly gram-positive ones, in the periapical lesions of teeth with refractory apical periodontitis.

Morphometric observations on the root canals of human molars

The theoretical possibility of using a standardized endodontic preparation and obturation technique in molars was investigated by measuring the widths of the roots and root canals of 40 teeth. Providing the canals were not too curved, circular-shaped preparations might be made with acceptable frequency only in the apical 1 to 3 mm of the buccal roots of maxillary molars and at the 1-mm level from the apex in the distal roots of mandibular molars. Theoretically, this technique is not generally applicable in molars.

Mandibular premolars with more than one root canal in different race groups

There has been a feeling among our faculty that in black patients the percentage of mandibular premolars with more than one canal is higher than in white patients. Radiographs of the mandibular premolars of 400 black patients and 400 white patients were studied by three endodontists without knowledge of the patients name or race. The criteria for determining the number of roots and root canals were the standard methods of radiographic appraisal. The number of first premolars with more than one canal in black patients was significantly higher than in white patients (32.8% versus 13.7%). In the second premolar the difference between black and white patients failed to reach significance (7.8% versus 2.8%). Significantly more black patients than white patients had at least one premolar with more than one canal (39% versus 15.8%). When first premolars with two separate roots were compared, again a significantly higher number was found in black patients than in white patients (16.2% versus 5.5%). Four of 10 black patients had at least one lower premolar with two or more canals.

Morphometric observations on root canals of human premolars

The theoretical possibility of using a standardized endodontic preparation and obturation technique in premolars was investigated by measuring the widths of the roots and root canals of 80 teeth. Providing the canals were not too curved, circular-shaped preparations might be made with acceptable frequency in the apical 2 to 3 mm of maxillary second premolars and mandibular premolars. Theoretically,this technique is not generally applicable in maxillary first premolars.

Assessment of periradicular microbiota by DNA‐DNA hybridization

Abstract – In the present study the “checkerboard” DNA‐DNA hybridization technique was used to identify bacteria in periapical endodontic lesions of asymptomatic teeth. Thirty‐four patients with root‐filled teeth and apical periodontitis were divided into two groups, each containing 17 patients. In Group 1, a marginal incision was performed during surgery to expose the lesion, and in Group 2, a submarginal incision was applied. The gingiva and mucosa were swabbed with an 0.2% chlorhexidine gluconate solution prior to surgery. Bacterial DNA was identified in all samples from the two groups using 40 different whole genomic probes. The mean number (±SD) of species detected was 33.7±3.3 in Group 1 and 21.3±6.3 in Group 2 (P<0.001). The majority of the probe‐detected bacteria were present in more lesions from Group1 than from Group 2. The differences were most notable for Campylobacter gracilis, Porphyromonas endodontalis, Propionibacterium acnes, Capnocytophaga gingivalis, Fusobacterium nucleatum ssp. nucleatum, Fusobacterium nucleatum ssp. polymorphum, Prevotella intermedia, Treponema denticola, Streptococcus constellatus and Actinomyces naeslundii I. Bacterial species such as Actinobacillus actinomycetemcomitans and Bacteroides forsythus were detected in more than 60% of the lesions from both groups. Also, P. endodontalis was abundant in periapical tissue. The data supported the idea that following a marginal incision, bacteria from the periodontal pocket might reach the underlying tissues by surgeon‐released bacteremia. The study provided solid evidence that bacteria invade the periapical tissue of asymptomatic teeth with apical periodontitis. The detection of much more bacteria with the “checkerboard” DNA‐DNA hybridization method than has previously been recovered by anaerobic culture indicated that the endodontic (and periodontal) microfloras should be redefined using molecular methods.

Morphometric observations on root canals of human anterior teeth

The theoretical possibility of using a standardized endodontic preparation and obturation technique in anterior teeth was investigated by measuring the widths of the roots and root canals of 100 teeth. Providing the canals were not too curved, circular-shaped preparations might be made with acceptable frequency in the apical 5 mm of maxillary central incisors and canines, and in the apical 3mm of mandibular canines. A circular canal might be prepared in maxillary lateral incisors and mandibular incisors only at the 1-mm level from th apex.

Pulpal changes in replanted and autotransplanted immature teeth of dogs

The purpose of the present investigation was to study pulpal changes in replanted and autotransplanted immature teeth 4, 10, 30, and 180 days after the operation. At the end of the observation periods, angiography was performed and the dogs were killed. The teeth were sectioned at 4μm in a buccolingual direction and stained with hematoxylin and eosin, or with the van Gieson or the Brown and Brenn methods. However, repair occurred through ingrowth of a well vascularized, cellrich connective tissue that reached the pulp horn after approximately 30 days. In the majority of the teeth observed after 180 days, the soft tissue of the pulp was markedly reduced in cells and blood vessels. Cell-containing atubular hard tissue occupied most of the original pulp cavity. In a few teeth, the original pulp tissue seemed to have survived. In these teeth, the pulp exhibited a normal appearance with an intact odontoblastic layer.

Experimentally induced pulpitis

Abstract Cavities were prepared in forty-five teeth from four monkeys. Soft carious human dentine was placed in fifteen cavities, which were then filled with amalgam. Guttapercha temporary fillings were placed in seventeen teeth, and thirteen cavities were left unfilled. After about 8 days the animals were killed and the teeth were examined histologically. The insertion of carious dentine and amalgam resulted in a localized, severe pulp reaction, whereas gutta-percha gave a slight to moderate reaction. Both of these methods of inducing pulpitis were considered to be suitable for further studies related to pulpal healing. The pulp responses to open cavities varied considerably.