Bite force and its correlations in different denture types.

Maximal bite force was measured and intraoral condition was examined in 89 patients at the Institute of Dentistry, University of Turku. These patients formed three different denture groups: those with complete dentures, those with full maxillary denture and partial mandibular denture, and those with natural dentition or skeleton-supported partial maxillary denture and partial mandibular denture. There were three age groups: greater than or equal to 70, 60-69, and less than or equal to 59 years old. Maximal bite force was recorded with an appliance at seven different measuring points by placing a biting fork between the antagonistic teeth while at the same time the occlusion was stabilized contralaterally with a plastic tube. Maximal bite force had a correlation with age and sex (P less than 0.01). In partial-denture groups high bite force had a correlation with the breaking of dentures (P less than 0.001 and P less than 0.05, respectively). Satisfied patients had a higher bite force than dissatisfied ones. When there was some disturbance in occlusion, the bite force was smaller, especially in full-denture groups (P less than 0.001). Full-denture wearers also had a good bite force, but the best biting area was located more posteriorly than in patients who still had some natural teeth left in both jaws. Changes in the denture-bearing mucosa in patients with complete dentures and negative height of the mandibular alveolar process decreased the bite force slightly.

Periodontium and occlusal disorders in rats with experimental arteriosclerosis. A histological study.

Rats with arteriosclerosis induced by a hypercholesterolic diet were over a period of six weeks submitted to occlusal disorders. Hyperfunction was established by a high filling in the first mandibular molar, and hypofunction was achieved by removing the antagonist tooth. Histological examination revealed an increased number of inflammatory cells in the gingiva surrounding the disordered tooth, both in the experimental and the control animals. During the six weeks of occlusal disorder, however, a marked increase in the number of inflammatory cells, as well as epithelial proliferation and deepening of the gingival pocket in the gingival sulcus area, was observed in one-third of the experimental animals. This frequency was statistically higher than that found in the controls at the p less than 0.05 level. In all the experimental animals the gingival connective tissue showed degenerative changes. The apposition of alveolar bone had diminished and osteoclastic resorption had increased. In the control animals the periodontal effects of the occlusal disorders were slight.

Deteriorating effect of occlusal disorders on the periodontium of rats with experimental arteriosclerosis.

The periodontal effects of food consistency and of experimental occlusal stresses were clinically studied with healthy and arteriosclerotic rats. Experimental arteriosclerosis was induced with a hypercholesterolemic diet continued for 6 -- 12 months. By using food that was finely powdered and moistened, mechanical irritation of the periodontium was reduced to a minimum. The special occlusal and gingival irritants lasting six weeks were an occlusal overload with an overhigh amalgam filling, or an occlusal hypofunction caused by extracting the antagonist tooth. The arteriosclerotic animals with experimental occlusal stress had gingival changes adjacent to the loaded tooth distinctly more often than around the control tooth on the contralateral side of the mandible of the same animal (P less than 0.001). The changes seen were local redness and inflamation, and an excessive hyperplastic growth of the gingiva. The gingival changes on the stressed side in control animals were generally slight and the difference compared to the contralateral side was not statistically significant. The control animals showed recession of the gingiva more often than hyperplastic growth of same. In both groups of animals food impaction and deposit of calculus had increased around the teeth that were in occlusal hypofunction. The inflammatory changes were more frequent in the arteriosclerotic animals than in the controls. The cause of the deterioration in the ability to repair tissue damage in arteriosclerotic animals is discussed.

Late results of treatment with partial dentures. An investigation by questionnaire and clinical examination 13 years after treatment.

Ninety-nine people who were fitted with partial dentures in 1959 were invited to take part in an investigation 13 years later. A questionnaire was answered by fifty-eight, which means a frequency of 81% if allowance is made for an explainable loss. Of the sixty-eight partial dentures in these fifty-eight patients, twenty-three were still being used, fourteen patients had had their original partial dentures replaced by new ones and three by a fixed bridge, while seven had been replaced by complete dentures. Twenty-one were no longer used and had not been replaced. Of the fifty-four patients who originally had a complete upper denture and a partial lower denture, thirty were still available. Following an invitation to take part in a clinical review, twenty-seven (90%) co-operated. Most of the patients were in need of treatment (for caries, periodontitis and/or prosthetic treatment). The periodontal injuries were rarely serious. A correlation was found between good oral hygiene and good results of treatment.