Is bovine dentine an appropriate substitute for human dentine in erosion/abrasion tests?

Summary  The study aimed to compare the dentine wear of primary and permanent human and bovine teeth because of erosion/abrasion and evaluate if bovine dentine is an appropriate substitute for human dentine in further erosion/abrasions tests. Dentine samples from deciduous molars and human third molars as well as from calves' and cattle's lower incisors were prepared and baseline surface profiles were recorded. Each day all samples were demineralized in 1% citric acid, tooth brushed with 100 brushing strokes with toothpaste slurry and stored in artificial saliva for the rest of the day. This cycle was run for 20 days. Afterwards, new surface profiles were recorded and dentine wear was calculated by a customized computer program. Dentine wear because of erosion/abrasion was not statistically, significantly different for human third molars and cattle's lower incisors ( P  = 0·7002). The dentine wear because of erosion/abrasion of deciduous molars and calves' lower incisors was significantly different ( P  < 0·0000). No statistically significant difference in the dentine wear of human third molars and cattle's lower incisors was observed, so that the use of cattle's lower incisors as substitute for adult human teeth for further investigations in erosion/abrasion studies could be accepted.     

Comparative immunohistochemical analysis of the peptidergic innervation of human primary and permanent tooth pulp

This immunohistochemical study sought to determine whether there are any differences in the peptidergic innervation of these pulps and whether dental caries is associated with changes in neuropeptide expression. Mandibular first permanent molars and second primary molars (n=120) were obtained from children requiring dental extractions under general anaesthesia. Extracted teeth were split longitudinally, placed in fixative, and categorized as intact, moderately carious or grossly carious. The coronal pulps were removed and 10-microm frozen sections were processed for indirect immunofluorescence. Double labelling employed combinations of the following antisera: (1) protein gene product 9.5, a general neuronal marker; (2) one of the neuropeptides calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), galanin (GAL), enkephalin (ENK) and somatostatin (SOM). Image analysis was then used to determine the percentage area of immunostaining for each label within different anatomical regions of the coronal pulp. Sparse or absent immunoreactivity for GAL, ENK and SOM made analysis impossible. Analysis of CGRP, SP and VIP revealed significant interdentition differences, with their expression being significantly greater in permanent teeth, but this was not the case for NPY, with primary and permanent teeth demonstrating a similar amount of label for this peptide. Both dentitions showed significant increases in CGRP, SP, VIP and NPY expression with caries progression. These findings could have biological and clinical importance in connection with nociception, inflammation and healing.     

A study of the ability of an in situ remineralization model to differentiate between the effects of two fluoride dentifrices that produced significantly different clinical caries results.

The purpose of this study was to determine whether an in situ remineralization model was able to show a difference in the effects of two dentifrices of different fluoride concentrations and significantly different clinical efficacies. Three dentifrices were tested in a double-blind, cross-over study design. The products contained 0 ppm F, 250 ppm F, or 1000 ppm F from sodium fluoride and were formulated with a silica base according to the formulations used in a human caries trial (Koch et al., 1990). Nineteen subjects each carried three or four thin sections of enamel in their partial dentures. The thin sections, containing artificial caries lesions, were covered with a steel mesh to provide space for plaque formation and then brushed in situ three times daily with the dentifrices. Following the two-week treatment periods, the specimens were removed from the dentures and analyzed for changes in mineral content. The findings showed that the placebo dentifrice (0 ppm F) resulted in 56.8 +/- 74.3% demineralization, the 250-ppm-F dentifrice produced 12.9 +/- 41.3% demineralization, thereby showing partial caries protection, and the 1000-ppm-F dentifrice produced 17.3 +/- 32.1% remineralization. Linear regression analysis showed that the percent remineralization was significantly related to the fluoride concentration in the dentifrice (p less than 0.001). The 250-ppm-F dentifrice was also significantly less effective than the 100-ppm-F dentifrice (p = 0.04, one-tailed Fisher Protected LSD test). These findings are in accord with the human caries trial and support the use of the present in situ remineralization model for prediction of the anticaries efficacy of fluoride dentifrice products.     

Double-Blind Whitening Night-Guard Study Using Ten Percent Carbamide Peroxide

The conservative technique of professionally dispensed and supervised, home-administered vital bleaching is now a routine treatment in the dental profession. This double-blind study evaluated the Rembrandt Lightening Gel and Whitening Toothpaste for shade change, colorimeter shade change. As well, it evaluated soft tissue health by periodontal probing, plaque index, and bleeding index. A patient questionnaire evaluated perception of whitening, perception of oral hygiene, average hours per day, and average days per week. Bleaching trays were worn over a 4-week period. The bleaching system showed definitive whitening effects as evaluated with the Vita shade guide and the colorimeter. The bleaching system had no deleterious effects on the soft tissue. The Rembrandt toothpaste alone demonstrated two-shade lightening. This vital bleaching system shows definitive whitening of the teeth in short periods of time with no adverse effects.     

Oral lichenoid dysplasia: a clinicopathologic analysis

Three women had a diagnosis of oral lichen planus (OLP), which was made on the basis of clinical and histologic features. All three had persistent burning pain associated with large mucosal lesions. Changes in the color (red, red and white, white), configuration, and severity of the lesions were unpredictable and did not correlate well with topical corticosteroid therapy. Only one patient used tobacco (cigarettes)--this patient had recurrent oral candidiasis and was receiving multiple medications. One of the two nonsmokers was a denture wearer with a single episode of candidiasis. After 63, 32, and 56 (mean 50) months, carcinoma developed in all three. In retrospect, the initial biopsy specimens of two patients exhibited lichenoid dysplasia, whereas that of the third showed only lichenoid mucositis. Although speckled erythroplakia was the earliest clinical sign of a classic, nonregressing premalignant lesion, it already signaled the presence of invasive carcinoma. Some early epithelial dysplasias appear to have a robust inflammatory/immunologic response to the antigenically (but as yet not histologically) altered dysplastic epithelium and a high probability of at least temporary resolution. Mucosal erythema of obscure origin displaying spontaneous, usually temporary, partial to complete regression may be common to both purely inflammatory conditions like lichen planus and early epithelial dysplasia. We contend that some, if not most, cases of apparent malignant transformation of OLP likely represent red and white lesions that were dysplastic from their inception but that mimic OLP both clinically and histologically.     

Re-epithelialization of a palatal connective tissue graft transplanted in a non-keratinized alveolar mucosa: A histological and biochemical study in humans

This study was undertaken to evaluate the type of tissue obtained after transplantation of a connective tissue graft, from the same palatal donor site, into a non-keratinized oral mucosa in humans. In 6 human volunteers, a thick palatal epithelio-connective tissue graft was excised, split into two thinner grafts (a thin epithelio-connective tissue graft and a connective tissue graft) and transplanted into controlateral areas lacking keratinized gingiva. The biopsies, excised 3 months post-operatively, were examined using routine histology, immunofluore-scence techniques with different anticy to keratin antibodies and biochemical techniques with non-equilibrium two-dimensional gel electrophoresis. The results show that the epithelio-connective tissue grafts display the histological and biochemical characteristics of keratinized gingiva, whereas the connective tissue grafts expressed features belonging both to keratinized and non-keratinized gingival tissues. It is concluded that the deep palatal connective tissue does not have the full potential to induce non-keratinized epithelial cells to keratinize and that a gingival or palatal connective tissue graft without its overlying epithelium is not likely to yield genuine attached gingiva.     

Viadent, ethanol, and pH effects upon gingival epithelial-like cells, in vitro

Interest has recently been directed towards the use of antiplaque mouthrinses. Most published material concerns the antimicrobial effects of these agents rather than their effects upon oral tissue. This study was conducted to evaluate the effect of a sanguinarine-containing mouthrinse called Viadent upon epithelial-like gingival cells. The cells were grown for 24 hours in supplemented Earle's medium, with and without different Viadent dilutions. Cell counts were made with a hematocytometer. It was found that 50% of the cells were inhibited at 1.2% Viadent. In similar studies, it was found that 70% ethanol and two pH buffers were less toxic than Viadent. Exposure of preformed cell monolayers to Viadent also showed significant inhibition. The relative toxicity of different antiplaque agents may be compared using such cells as a model system. In conclusion, it was observed that Viadent significantly affected gingival cell growth in vitro, that viable cell numbers were greatly reduced by short time exposure, and that the toxic effect of Viadent could only partially be accounted for by ethanol content and/or pH.     

The release of interleukin-1β, tumor necrosis factor-α and i nterferon-γ by cultured peripheral blood mononuclear cells from patient swith periodontitis

The extracellular release of IL-1 beta by cultured peripheral blood monocytes from 26 periodontitis patients and 26 control subjects was measured by radioimmunoassay. Unstimulated monocytes from periodontitis patients released significantly more IL-1 beta than controls during 24 h of culture; there was a wide variation in the amount of IL-1 beta released (0.45-13.00 ng/ml per 10(6) cells) which did not correlate with either the degree of bone loss or pocket formation observed clinically. When stimulated with lipopolysaccharide (LPS; Actinobacillus actinomycetemcomitans; 5 micrograms/ml) monocytes from periodontitis patients produced significantly more IL-1 beta than those from control subjects. Monocyte culture supernatants from another 10 periodontitis patients and 10 control subjects were also assayed for both IL-1 beta and TNF-alpha by enzyme-linked immunosorbent assays. Spontaneous and LPS-stimulated (Bacteroides gingivalis; 5 micrograms/ml) IL-1 beta release were again significantly higher for periodontitis patients. TNF-alpha was detected in the periodontitis cultures (0-765 pg/ml per 10(6) cells), but the mean value was not significantly different from controls. LPS-stimulated TNF-alpha release, however, was significantly higher than for control subjects, and there was a strong correlation between spontaneous IL-1 beta and TNF-alpha release by monocytes from the periodontitis group. Measurement of interferon-gamma (IFN-gamma) in lymphocyte cultures from these patients by immunoradiometric assay showed that IFN-gamma levels in periodontitis cultures were consistently low, but not significantly so when compared to controls; both groups responded equally to concanavalin-A (5 micrograms/ml). Although the precise roles of IL-1 beta and TNF-alpha in periodontitis remain unclear, these data provide evidence that both cytokines may participate in the pathogenesis of the disease.     

Light microscopic study of giant tubules in bovine dentin

Demineralized, H-E stained longitudinal and transversal sections of unerupted permanent incisors from 1/2-3-yr-old calves were studied by light microscopy. The most incisal dentin in all teeth was characterized by a regular pattern of straight axially oriented giant tubules situated in the axiomesiodistal plane with interglobular dentin between them. In younger teeth, the pulpal part of every giant tubule contained an afferent and an efferent blood vessel, forming a hairpin loop and being surrounded by basophil cells. Incisal to the blood vessel loops, cells enbedded in an eosinophil matrix were present in the giant tubule lumina, showing increasing degenerative changes incisally. In older teeth there was a mesiodistally extended eosinophil dentin band near the pulp, with few, irregularly arranged, tortuous dentinal and giant tubules, the latter containing single blood vessels accompanied by pulpal cells. Isolated degenerating odontoblasts in lacunar cavities were seen in the transition area of the normal circumpulpal dentin and the eosinophil dentin band. A hypothesis on the initiation and subsequent development of giant tubules is presented.     

Traumatized primary anterior teeth. Prognosis related to calcific reactions in the pulp cavity.

The frequency of a complicating pulp necrosis and the process of the physiologic root resorption were studied in traumatized primary teeth exhibiting partial or total pulp obliteration. The material comprised 88 incisors in 72 children aged 0.7--5.7 years (mean 2.9 years) at the time of injury. Trauma had resulted either in subluxation (25 teeth), or luxation (13 teeth), whereas the type of injury was unknown in 50 teeth. All cases were observed until eruption of the permanent incisors. Forty-four teeth initially displayed a reversible greyish color. The ultimate finding observed in all teeth was, however, varying degrees of yellow discoloration. Periapical pathologic findings indicative of pulp necrosis were observed in 9 teeth, from 1.6--4 years (mean 3 years) after the time of injury. Extraction was performed immediately, and none of the successional teeth showed developmental disturbances. The process of root resorption was classified as normal in all primary teeth. Subsequent eruption of the permanent successors occurred without any registered complications.