Arild Stenvik

Pulp and dentine reactions to experimental tooth intrusion. A histologic study of the initial changes

Abstract This report represents the first part of a study concerned with pulp and dentine reactions during tooth movement, The experimental material consisted of thirty-five intact teeth from children aged 10 to 13 years. These teeth were intruded with forces ranging from 35 to 250 Gm. with fixed appliances under controlled conditions for 4 to 35 days. All these teeth were extracted immediately after the force was removed. A similar number of untreated teeth served as controls. The main pulp changes in the experimental material included vacuolization of the pulp tissue and circulatory disturbances. Teeth with completed apices exhibited more severe changes than teeth with open apices, and the magnitude of the force was also important. In the teeth with incomplete root development, disturbances in the root formation frequently occurred. The resorption observed in dentine was related to the magnitude of the force and the duration of the experiment.

Three-year follow-up of bimaxillary surgery to correct skeletal Class III malocclusion: stability and risk factors for relapse.

INTRODUCTION The purpose of this study was to evaluate long-term skeletal and occlusal stability after bimaxillary surgery to correct skeletal Class III malocclusion. METHODS The sample comprised 81 consecutively treated patients. All subjects had received a combined 1-piece LeFort I and bilateral sagittal split ostotomies with rigid fixation between 1990 and 2003 and were followed for 3 years. Lateral cephalograms were obtained before surgery and at 5 occasions after surgery. RESULTS The mean setback was 6.9 mm in the mandible, and the maxilla was moved forward 3.7 mm. In most patients, the posterior maxilla was impacted. Relapse of maxillary advancement was insignificant (0.1 mm), whereas relapse at B-point was on average 1.7 mm (P <0.010). After 3 years, mean overjet and overbite amounts were 2.0 and 1.9 mm, respectively. Skeletal relapse of the mandible increased significantly with the surgical setback (P <0.001) and the change in the vertical position of the posterior maxilla (P = 0.010) (multivariate regression analysis). CONCLUSIONS Bimaxillary surgery resulted in good occlusal stability. Maxillary advancement was stable, whereas relapse of the mandibular setback varied. Risk factors for horizontal relapse of the mandible were large setback and inferior repositioning of the posterior maxilla.

Three-year stability of open-bite correction by 1-piece maxillary osteotomy.

INTRODUCTION The purpose of this retrospective cephalometric study was to evaluate the long-term vertical stability of anterior open-bite correction by 1-piece Le Fort I osteotomy and rigid fixation. METHODS The sample comprised 40 consecutively treated patients from the files of the Department of Orthodontics, University of Oslo, Norway. All subjects had received a 1-piece Le Fort I osteotomy as the only surgical procedure from 1990 through 1998 and were followed for 3 years according to a protocol for data collection. Lateral cephalograms were obtained before surgery and at 5 occasions after surgery. RESULTS The mean open bite before surgery was 2.6 mm; at the 3-year follow-up, 35 patients had a positive overbite, and the remaining 5 patients had an open bite between 0.2 and 0.9 mm. Impaction of the posterior maxilla >or=2 mm relapsed on average by 31%, and inferior repositioning of the anterior maxilla >or=2 mm relapsed by 62%. Maxillary vertical skeletal changes during the postsurgery period were compensated for by orthodontic dentoalveolar adaptation. Most of the skeletal relapse occurred during the first 6 months after surgery and always in the direction opposite to the surgical movement. The relative contribution of mandibular and maxillary changes in anterior open-bite closure was approximately 3:1. CONCLUSIONS Surgical correction of anterior open bite was generally stable over a 3-year period, and skeletal relapse was counteracted by dentoalveolar compensation.

TISSUE PRESSURE AND HISTOLOGY OF NORMAL AND INFLAMED TOOTH PULPS IN MACAQUE MONKEYS

Abstract Sixty-two registrations of the pulp pressure in 25 teeth were performed by means of a measuring technique which makes possible successive registrations from the same tooth. The results demonstrate that the method is fairly reliable, and corroborate clinical and histologic observations in the same teeth. Pressure values in the monkey pulp averaged 16 mm Hg at the initial registration. However, variations in the pressures were registered which may be due to tissue damage or result from general and regional circulatory variations. A local pulp reaction was induced by the measuring technique. Subsequent registrations were conducted to relate pulp physiology to structural changes associated with the development of an inflammatory process. Inflammation in the pulp appeared to be accompanied by increased pressures amounting to 50–60 mm Hg but, as the process advanced into the radicular pulp leaving necrotic tissue at the registration site, pressures below the initial values were recorded.

Taurodontism and concomitant hypodontia in siblings

Abstract Four Norwegian siblings exhibiting taurodontism, oligodontia, and characteristic facial features of ectodermal dysplasia are discussed. The present material supports observations previously reported in the literature which indicate that taurodontism may be related to general or dental disturbances rather than, or possibly in addition to, being a specialized form of teeth in some prehistoric anthropoids. However, more evidence is needed before decisive conclusions can be reached as to the nature of taurodontism.

The effect of experimental tooth intrusion on pulp and dentine

Abstract A study of sixty teeth from children 10 to 13 years of age reveals that marked changes may occur in the dentine and pulp as a result of tooth intrusion with continuously acting forces. The pulp reactions were most manifest in teeth in which the apical area was complete. Alterations in apical anatomy were found only in teeth in which the root was not complete, while resorption defects were noted in most teeth in the experimental material. The changes were most marked in teeth subjected to large forces, but no definite limit of tolerance can be established on the basis of these investigations. Some of the alterations noted were of a permanent nature, while others were considered to be at least partly resolvable following removal of the intrusive force.

Bedarf und Wunsch nach kieferorthopädischer Behandlung bzw. Wiederbehandlung bei 35jährigen Norwegern

Long-term outcome of orthodontic care systems may be studied by examining malocclusion and treatment need in groups of treated and untreated adults. The objective of the present work was to investigate the professionally defined need as well as the need perceived by the individuals in an attempt to study the outcome of orthodontic services. The material comprised data from 111 individuals collected from a random sample of 35-year-olds from Oslo, Norway. From a clinical examination and measurements on dental study casts, the subjects were classified into either of 4 levels of need according to the Need for Orthodontic Treatment Index (NOTI) used by the Norwegian Health Insurance System. Perceived need for treatment was analyzed from responses to questions about satisfaction with dental appearance and desire for orthodontic treatment presented in a questionnaire. Satisfaction with dental appearance was recorded in 85% and 92% of untreated and previously treated, respectively. Desire for treatment was expressed by 19% of the untreated and 3% of the treated individuals. Occlusal anomalies were present among both the treated and untreated subjects, and the clinical significance of the malocclusion traits observed is discussed.ZusammenfassungAnhand einer Untersuchung der Zahnfehlstellung und des Behandlungsbedarfs bei Gruppen von behandelten und unbehandelten Erwachsenen können die langfristigen Ergebnisse der kieferorthopädischen Therapie erforscht werden. Ziel der vorliegenden Arbeit war es, die Ergebnisse der kieferorthopädischen Behandlungen zu untersuchen, um sowohl den ärztlich definierten als auch den vom einzelnen empfundenen Bedarf zu ermitteln. Das Untersuchungsmaterial umfaßt Daten von 111 unselektierten 35jährigen aus Oslo, Norwegen. Anhand einer klinischen Untersuchung und Analysen von dentalen Studienmodellen wurden die Probanden in eine von vier Bedarfskategorien nach dem norwegischen Indikationssystem („Need for Orthodontic Treatment Index“ [NOTI]), das von der staatlichen Sozialversicherung angewendet wird, eingeteilt. Mittels eines Fragebogens wurde nach der Zufriedenheit mit der eigenen dentofazialen Ästhetik und dem Wunsch, sich einer kieferorthopädischen Behandlung zu unterziehen, gefragt. Danach wurden die Antworten hinsichtlich des vom einzelnen empfundenen Behandlungsbedarfs analysiert. Zufriedenheit mit der eigenen dentofazialen Ästhetik wurde bei 85% der unbehandelten und 92% der früher behandelten Probanden festgestellt, während der Wunsch nach einer Behandlung bei 19% der unbehandelten und 3% der behandelten Probanden bestand. Okklusale Anomalien wurden sowohl bei behandelten als auch bei unbehandelten Probanden festgestellt, und die klinische Signifikanz der Befunde in bezug auf Zahn/Kiefer-Fehlstellungen wird erörtert.SummaryLong-term outcome of orthodontic care systems may be studied by examining malocclusion and treatment need in groups of treated and untreated adults. The objective of the present work was to investigate the professionally defined need as well as the need perceived by the individuals in an attempt to study the outcome of orthodontic services. The material comprised data from 111 individuals collected from a random sample of 35-year-olds from Oslo, Norway. From a clinical examination and measurements on dental study casts, the subjects were classified into either of 4 levels of need according to the Need for Orthodontic Treatment Index (NOTI) used by the Norwegian Health Insurance System. Perceived need for treatment was analyzed from responses to questions about satisfaction with dental appearance and desire for orthodontic treatment presented in a questionnaire. Satisfaction with dental appearance was recorded in 85% and 92% of untreated and previously treated, respectively. Desire for treatment was expressed by 19% of the untreated and 3% of the treated individuals. Occlusal anomalies were present among both the treated and untreated subjects, and the clinical significance of the malocclusion traits observed is discussed.

The prognosis of retained primary molars without successors: infraocclusion, root resorption and restorations in 111 patients

This study aimed to assess infraocclusion, root resorption and restorations and their importance for the prognosis of retained primary mandibular molars lacking successors. The sample comprised 188 persisting primary mandibular second molars in 111 subjects, 48 males and 63 females, with a mean age of 12.6 years. The patients had been referred to an interdisciplinary clinic because of extensive hypodontia, missing 8.4 teeth on average. All persisting primary mandibular molars were included in the study, as no decision had been made as to whether they should be kept or extracted. Panoramic radiographs were used to assess infraocclusion, resorption of the mesial and distal roots and whether restorations were present. Clinically significant infraocclusion was observed in 43.6 per cent of the patients and classified as severe in 18.8 per cent. The mesial and distal root exhibited no resorption in 18.9 and 33.3 per cent, respectively (P = 0.01). Most primary molars had no restorations (78.4 per cent). A significant correlation was found between root resorption and infraocclusion. Age was found to be weakly but significantly correlated with root resorption and infraocclusion. No significant relationship was observed between gender and either infraocclusion or root resorption. In conclusion, infraocclusion was estimated to be a more critical factor for the prognosis of retained primary molars than root resorption.

Microradiography and histology of decalcified human teeth following experimental intrusion; with emphasis on resorption

Abstract Young premolars which had been experimentally subjected to intrusive forces were studied. The microradiographic technique employed was considered to show variations in the mass distribution of organic material, and stained sections were used to show general morphology. The organic matrix was evenly removed during resorption. Two major types of odontoclasts and osteoclasts were distinguished on the basis of their radiodensity and stainability. Increased radiodensity of the predentine from that seen normally and disintegration of the vessel walls caused by circulatory disturbances could also be recognized in the experimental material using the microradiographic technique.

Root length in transplanted premolars

The objectives of the present prospective longitudinal study were to establish the survival and success rates for premolars with partly developed roots transplanted according to a set protocol, and to analyze the effect of varying pre‐surgery root development on final root length. Standardized periapical radiographs of 132 consecutively transplanted premolars were obtained at predetermined intervals over a 4‐year follow‐up period. Survival and success rates were calculated on the basis of presence of teeth and recording of defined radiological variables, respectively. Final root length was compared to normative metric data for root morphology. From the total sample, 54 patients with 68 transplanted premolars suitable for analysis of root growth relative to initial root length were identified, and divided into subsamples according to root length pre‐transplantation. Survival rates were 100% after 1, 2, and 3 years, and 98.6% 4 years post‐transplantation. The success rates were 92.9%, 92.8%, 89%, and 90.5% in subsamples collected 1, 2, 3, and 4 years after transplantation, respectively. The transplants obtained on average 78% of normative root length, and by dichotomizing the transplanted teeth in subsamples with ‘short’ and ‘long’ roots pre‐surgery, similar final root lengths were observed even if ‘short’ roots had the greatest increase. Very early transplantation (roots <7 mm), however, tended to result in short final root length. It is concluded that the success and survival rates were comparable to results obtained in similar studies. Initial root length was a significant predictor of root length increase. Transplanting teeth with short roots is to risk short final root length.