Alteration in directional specificity of interdental dimension discrimination with the degree of mouth opening

The interdental dimension discrimination (IDD) ability was tested at seven different degrees of mouth opening: 40 mm, 30 mm, 20 mm and 10 mm openings for the dentate subjects, and 10 mm opening, intercuspal position (ICP) and the ICP minus 5 mm for the edentulous subjects. The subjects were asked to discriminate between pairs of sticks held alternately between the upper and lower incisors. The IDD ability, evaluated in terms of the 50% difference limen (DL), did not differ significantly between any two of the tests conducted at seven different openings, although the number of misjudgments of the dentate subjects tended to increase with the degree of mouth opening. On the other hand, the directional specificity of the IDD, which is a tendency to overestimate the dimension of the first stick of each pair, developed almost linearly with a decrease in the opening degree. These findings indicate that the behaviour of the receptors concerned varies with the intermaxillary distance. Some edentulous subjects could not perceive the presence of a small test stick at the overclosed position (ICP - 5 mm), but vibration applied to the mandible enabled the subjects to detect the stick at the same opening. These results support the assumption that the muscle spindles of the jaw-closing muscles are the receptors responsible for the IDD.     

Chronology of an interdental periodontal lesion

Abstract A case in which intermittent and spontaneous periodontal breakdown and repair has occurred on two different occasions in the same interproximal site over a period of 18 years is described. The possible etiology of the lesions is discussed in terms of current concepts of localized bacterial selectivity. Also reviewed is the potential for repair in two-walled infrabony defects.     

Effects of the interpolated vibratory stimulation on the interdental dimension discrimination in normal and joint defect subjects.

No significant differences in the interdental dimension discrimination (IDD) ability were found between normal and joint defect subjects. Furthermore, vibration onto the mandible gave similar effects on the nature of IDD in both subject groups. Thus, the muscle spindles of masticatory muscles may contribute to IDD, but temporomandibular receptors may not.     

The role of the necrotic periodontal membrane in cementum resorption and ankylosis

Abstract Teeth replanted with non-vital periodontal membranes demonstrate a high incidence of root resorption and ankylosis. It has been suggested that necrotic periodontal membrane remnants actively stimulate resorption of the resistant cementum layer. The aim of this study was to examine resorption and ankylosis patterns following replantation of teeth with chemically denuded root surfaces and, by extrapolation from these data, to suggest a role for the necrotic periodontal membrane in resorption and ankylosis. Monkey incisors were replanted after endodontic therapy and immersion in 10% sodium hypochlorite. Teeth were either examined with scanning electron microscopy at intervals from 1 day to 8 wk, or subjected to light microscopic examination, using a morphometrical evaluation technique, at 8 wk post-replantation. Only a few macrophage-like cells, in relation to shallow resorption lacunae, were observed by 8 wk. Histologically, the alveolar bone had approached an apparently intact cementum surface in 93% of the morphometrically recorded points. This bone appeared to lie in close approximation to the cementum surface. Denuding the root surface of periodontal membrane prior to replantation demonstrated the resistance of the cementum to colonization and resorption in the absence of stimulation from necrotic periodontal membrane remnants. Furthermore, it revealed that bone replacing the periodontal membrane space grew from the alveolus towards the cementum, to which it appeared unable to fuse due to the absence of significant resorption. Thus, removal of a non-vital periodontal membrane may result in slower destruction of tooth substance following replantation of teeth with severely damaged periodontal membranes.     

Loss of anterior interdental tissue: periodontal and prosthodontic solutions

The restoration of anterior spaces with a loss of interdental tissue has been reviewed. A surgical technique combining a subepithelial connective tissue autograft and a free gingival graft has been described. This preprosthodontic surgical approach is recommended as the treatment of choice. When surgery is contraindicated, the use of a cantilevered porcelain papilla is suggested.     

Effects of interdental osteotomies on the periodontal and osseous supporting tissues

The effects of 40 interdental osteotomies on surrounding osseous and periodontal structures were evaluated clinically and radiographically. No statistically significant changes were noted in any of the clinical parameters except gingival height, which decreased slightly in the maxilla and increased in the mandible. These changes were found to be statistically significant, but not clinically significant, and are most likely explained by the direction of movement of the bony segment. Radiographic evaluations revealed no statistically significant changes other than an increase in interdental width in both the maxillary and mandibular sites. These measurements were made at the root level, and, although the crowns were moved closer, the roots may actually have flared apart because the anterior segment was tipped to upright the incisors. The lack of change in the other radiographic parameters indicated that there was no loss of alveolar bone support.     

Effect of interdental brush design on plaque during nonsurgical periodontal therapy

Clinical Oral Investigations - The aim of this randomized controlled trial was to evaluate the interproximal cleaning efficacy of waist-shaped compared with straight soft interdental brushes in...     

The effect of maximal mouth opening on dimension discrimination

The ability of twenty-five young persons to discriminate dimensions was tested. A reference stick of 10 mm was placed between the teeth, alternating with test sticks of different heights. After application of the reference stick the subjects were asked to open the mouth maximally. A test stick was placed on the lower incisors and the subjects closed the mouth slowly, until their upper incisors contacted the test stick. The subjects were then asked to assess whether a test stick felt higher or lower than the reference stick. Using this experimental method, it was found that incorrect assessments were symmetrically distributed around the 10 mm reference stick. A receptor mechanism is proposed, and applied to explain the results of the present and a previous experiment.     

The role of complement in periodontal diseases

The complement system has been implicated as both a pathogenic mechanism and a means of protection in periodontal diseases. It is well known that bacteria activate complement; such activation can initiate a number of events, including bacterial opsonization and killing, release of inflammatory agents, and modulation of other immune reactions. Cleavage of complement proteins has been observed in gingival fluids from individuals with periodontal disease and some investigators have observed complement deposition in diseased gingival tissues. Furthermore, a number of bacterial from individuals with periodontal diseases have been found to activate complement in vitro; some of these organisms appear to have the capacity to evade opsonization due to their proteolytic capacity. However, concrete evidence is not yet available that indicates that complement activation occurs in human periodontal disease and is important in either its pathogenesis or in protection against bacterial virulence factors.     

The role of occlusion in periodontal disease

Observations made from animal experiments have implicated jiggling forces' in the aetiology of some infra-bony defects. However, this article develops the hypothesis that advanced, localized bone defects may develop when teeth are overloaded and that these changes occur in patients who suffer from only a mild gingival inflammation.     

The interdental gingivae

Material from 20 young rhesus monkeys was prepared for study of the interdental gingival epithelium. An additional four young monkeys were injected with tritiated thymidine and radioautographs prepared for analysis of cell turnover.
It was found that the interdental gingiva between recently erupted teeth in proximal contact has a col form. The appearance of the col can be simulated by vertical sections close to the roots of single teeth. Analysis of sections through the actual col showed that it is always lined by squamous epithelium, five or more cell-layers thick, without any recognizable ameloblasts. The radioautographs showed consistent evidence of thymidine uptake, indicating cell-division, in all epithelia lining the col. It was concluded that the histological features and turnover-rate of epithelium in the interdental region are closely analogous to those of epithelium on other aspects of the teeth.
Clinical studies of the presence and amount of plaque and gingivitis in 1,075 intact interdental areas in 48 young adults showed a high degree of correlation between the presence and amount of plaque and the presence and severity of gingivitis, and lend support to the hypothesis that gingivitis starts interdentally because plaque accumulates there.     

The role of periodontal mechanoreceptors in mastication

The aim of this review is to discuss what is known about the reflex control of the human masticatory system by the periodontal mechanoreceptors and to put forward a method for standardised investigation. To deliver mechanical stimulus in a reproducible way, the following precautions are suggested: the stimulus should be brought into secure contact with the area of stimulation, and slack between the probe and the area to be stimulated should be taken up by the application of a preload. It is also important to ensure that there is minimal simultaneous activation of receptor systems other than the periodontal mechanoreceptors. It is also necessary to standardise the method for recording and analysing the response.