Ingvar Ericsson

Orthodontic forces and recurrence of periodontal disease. An experimental study in the dog.

Abstract The purpose of the present investigation was to assess the effect of orthodontic forces, which move teeth in a horizontal-mesial direction only, on remarkably reduced but healthy periodontal tissues. The experiments were carried out in five beagle dogs. Throughout the study, the animals were fed a soft diet which permitted dental plaque accumulation. At the start of the study (that is, on Day 0) the lower third premolars (3P; P3) were extracted and a phase of experimental periodontal breakdown was initiated by placing cotton floss ligatures around the neck of the teeth. After 210 days of plaque formation, and with the plaque collector in situ, the diseased periodontal tissues were surgically eliminated. During the surgical procedure a notch was prepared in the root surface at the level of the marginal termination of the alveolar bone. The notch later served as the reference point for measurements made in histologic sections. After 60 days of healing with plaque control (that is, on Day 270), orthodontic appliances, producing forces in order to move the lower fourth premolars (4P; P4) bodily in a mesial direction, were inserted. From Day 270 to Day 370, the test teeth (4P) were allowed to accumulate plaque while the control teeth (P4) were brushed daily. The dogs were killed on Day 370. Following death, tissue sections comprising 4P, 1M and P4, M1 were produced and subjected to microscopic analysis. The present investigation demonstrates that orthodontic forces moving individual teeth bodily are not capable of causing gingival inflammation in tooth regions where the periodontal support is remarkably reduced but non-inflammatory. The study also illustrates that the most important factor in the initiation, progression, and recurrence of periodontal disease is the microbial plaque present within the gingival pockets.The purpose of the present investigation was to assess the effect of orthodontic forces, which move teeth in a horizontal-mesial direction only, on remarkably reduced but healthy periodontal tissues. The experiments were carried out in five beagle dogs. Throughout the study, the animals were fed a soft diet which permitted dental plaque accumulation. At the start of the study (that is, on Day 0) the lower third premolars (3P; P3) were extracted and a phase of experimental periodontal breakdown was initiated by placing cotton floss ligatures around the neck of the teeth. After 210 days of plaque formation, and with the plaque collector in situ, the diseased periodontal tissues were surgically eliminated. During the surgical procedure a notch was prepared in the root surface at the level of the marginal termination of the alveolar bone. The notch later served as the reference point for measurements made in histologic sections. After 60 days of healing with plaque control (that is, on Day 270), orthodontic appliances, producing forces in order to move the lower fourth premolars (4P; P4) bodily in a mesial direction, were inserted. From Day 270 to Day 370, the test teeth (4P) were allowed to accumulate plaque while the control teeth (P4) were brushed daily. The dogs were killed on Day 370. Following death, tissue sections comprising 4P, 1M and P4, M1 were produced and subjected to microscopic analysis. The present investigation demonstrates that orthodontic forces moving individual teeth bodily are not capable of causing gingival inflammation in tooth regions where the periodontal support is remarkably reduced but non-inflammatory. The study also illustrates that the most important factor in the initiation, progression, and recurrence of periodontal disease is the microbial plaque present within the gingival pockets.

Orthodontic forces and recurrence of periodontal disease

Abstract The purpose of the present investigation was to assess the effect of orthodontic forces, which move teeth in a horizontal-mesial direction only, on remarkably reduced but healthy periodontal tissues. The experiments were carried out in five beagle dogs. Throughout the study, the animals were fed a soft diet which permitted dental plaque accumulation. At the start of the study (that is, on Day 0) the lower third premolars (3P; P3) were extracted and a phase of experimental periodontal breakdown was initiated by placing cotton floss ligatures around the neck of the teeth. After 210 days of plaque formation, and with the plaque collector in situ, the diseased periodontal tissues were surgically eliminated. During the surgical procedure a notch was prepared in the root surface at the level of the marginal termination of the alveolar bone. The notch later served as the reference point for measurements made in histologic sections. After 60 days of healing with plaque control (that is, on Day 270), orthodontic appliances, producing forces in order to move the lower fourth premolars (4P; P4) bodily in a mesial direction, were inserted. From Day 270 to Day 370, the test teeth (4P) were allowed to accumulate plaque while the control teeth (P4) were brushed daily. The dogs were killed on Day 370. Following death, tissue sections comprising 4P, 1M and P4, M1 were produced and subjected to microscopic analysis. The present investigation demonstrates that orthodontic forces moving individual teeth bodily are not capable of causing gingival inflammation in tooth regions where the periodontal support is remarkably reduced but non-inflammatory. The study also illustrates that the most important factor in the initiation, progression, and recurrence of periodontal disease is the microbial plaque present within the gingival pockets.The purpose of the present investigation was to assess the effect of orthodontic forces, which move teeth in a horizontal-mesial direction only, on remarkably reduced but healthy periodontal tissues. The experiments were carried out in five beagle dogs. Throughout the study, the animals were fed a soft diet which permitted dental plaque accumulation. At the start of the study (that is, on Day 0) the lower third premolars (3P; P3) were extracted and a phase of experimental periodontal breakdown was initiated by placing cotton floss ligatures around the neck of the teeth. After 210 days of plaque formation, and with the plaque collector in situ, the diseased periodontal tissues were surgically eliminated. During the surgical procedure a notch was prepared in the root surface at the level of the marginal termination of the alveolar bone. The notch later served as the reference point for measurements made in histologic sections. After 60 days of healing with plaque control (that is, on Day 270), orthodontic appliances, producing forces in order to move the lower fourth premolars (4P; P4) bodily in a mesial direction, were inserted. From Day 270 to Day 370, the test teeth (4P) were allowed to accumulate plaque while the control teeth (P4) were brushed daily. The dogs were killed on Day 370. Following death, tissue sections comprising 4P, 1M and P4, M1 were produced and subjected to microscopic analysis. The present investigation demonstrates that orthodontic forces moving individual teeth bodily are not capable of causing gingival inflammation in tooth regions where the periodontal support is remarkably reduced but non-inflammatory. The study also illustrates that the most important factor in the initiation, progression, and recurrence of periodontal disease is the microbial plaque present within the gingival pockets.

Long-term follow-up of cross-arch fixed partial dentures in patients with advanced periodontal destruction. Evaluation of the supporting tissues.

The aim of the study was to evaluate the periodontal conditions in patients treated more than 10 years ago for advanced periodontal disease and rehabilitated with cross-arch fixed partial dentures (FPDs). Of 50 randomly selected patients, 34 subjects carrying 43 FPDs agreed to participate in a clinical and radiographic follow-up examination. The FPDs were divided into three groups on the basis of prosthesis design (end abutments, unilateral cantilever, and bilateral cantilevers) and amount of supporting tissues at the time of bridge installation. Seventy per cent of the FPDs were found to be unchanged, whereas the rest had been modified due to various complications leading to extraction of one or more of the abutment teeth. Six FPDs (14%) had been partially replaced by FPDs anchored to osseointegrated dental implants. A total of 21 (8%) of the original 274 abutment teeth had been extracted. Longitudinal changes in the amount of periodontal support were minimal over the average of 15 years of follow-up. FPD design or initial amount of supporting tissues was found not to have significant influence on longitudinal changes in periodontal conditions. It was concluded that combined periodontal and prosthodontic treatment of patients with advanced loss of periodontal support may provide a high rate of long-term successful outcome, provided proper adequate periodontal and prosthetic treatment and maintenance care are given.

Occurrence and Distribution of Root Resorption in Orthodontically moved Premolars in Dogs

An experimental study in dogs, in which 15 teeth were bodily moved and 9 teeth were tipped with the same amount of horizontal force. Less resorption was found with tipping, and less was found on the mesial root surfaces moved into the extraction sites than on the furcation side of the distal roots.

Some anatomical features of the periodontium of the deciduous and permanent dentition in the beagle dog

The present study describes some anatomical characteristics of teeth and periodontal tissues in the deciduous and permanent dentition of the beagle dog. Five animals were used. At the age of 10 weeks (Period A) and 15 months (Period B), respectively, a plaque control period was initiated. At the end of each plaque control period, clinical examinations were performed. Biopsies were obtained from the 02P, 03P (Period A) and P3, P4 (Period B) tooth regions and were examined with the light microscope. Histometric and morphometric measurements were made. The macroscopic and microscopic measurements revealed that marked differences exist between the teeth and the periodontium of the deciduous and the permanent dentition. The permanent premolar erupting into the position of the deciduous premolar was found to be significantly wider and higher than its precursor. Also the shape of the crown of the permanent premolar differed from that of the deciduous premolar. The sinuous contour of the buccal gingival margin was more accentuated in the deciduous than in the permanent dentition. The free gingiva was shorter and the periodontal ligament space was wider in the deciduous than in the permanent dentition. The free gingival unit in the deciduous dentition consisted of a larger volume of epithelium and a smaller volume of connective tissue than the corresponding unit in the permanent dentition. The connective tissue of the deciduous gingiva contained a larger proportion of fibroblasts and a lower proportion of collagen fibres than the corresponding tissue of the permanent gingiva.